WO2019012431A1

WO2019012431A1 - Electric machine with integrated gearbox

Info

Publication number: WO2019012431A1
Application number: PCT/IB2018/055087
Authority: WO
Inventors: James Klassen; Christopher ESTERER
Original assignee: Genesis Robotics And Motion Technologies Canada, Ulc
Priority date: 2017-07-11
Filing date: 2018-07-10
Publication date: 2019-01-17

Abstract

A robot arm may have succession of rotatably connected segments defining axes of relative rotation aligned generally with longitudinal direction of the robot arm. The segments may be wedge shaped or otherwise have the axes of relative rotation of successive and preceding segments of a middle segments not being parallel to each other. Plural actuators may be arranged to drive relative rotation of the segments about the respective axes. A stepper motor controller may be connected to multiple actuators of the plural actuators, for driving respective electric motors of the multiple actuators. The actuators may have different mechanical advantage depending on positions of the arm and the actuators, and may have sufficient friction that actuators that are in positions having mechanical advantage above a threshold do not move when the actuators are not energized, or that all actuators do not move regardless of the position of the arm.

Description

ELECTRIC MACHINE WITH INTEGRATED GEARBOX

CROSS REFERENCE TO RELATED APPLICATIONS

This present application claims priority to U.S. Provisional Patent Application No.

62/531,346 filed July 11, 2017 the disclosures of which are incorporated by reference herein.

TECHNICAL FIELD

[0001 ] Actuators and robotics .

BACKGROUND

[0002] Certain types of robots, such as industrial or assistive robots, benefit from the following actuator characteristics: high payload capacity, integrated braking on all actuators, simple motor control and low cost. It is therefore desirable to obtain an actuator with one or more of these characteristics.

SUMMARY

[0003] There is provided a robot arm including a succession of segments, each successive segment of the succession of segments rotatably connected at a respective rotatable connection to a respective previous segment of the succession of segments, each respective rotatable connection defining a respective axis of relative rotation of the respective successive segment and respective previous segment, the respective axes being aligned generally with a longitudinal direction of the robot arm, at least one middle segment being a successive segment with respect to a previous segment connected to the middle segment at a first rotatable connection of the respective rotatable connections and the middle segment being a previous segment with respect to a successive segment connected to the middle segment at a second rotatable connection of the respective rotatable connections, the middle segment being shaped so that the respective axes of the first rotatable connection and the second rotatable connection are not parallel to each other, and plural actuators arranged to drive relative rotation of the segments about the respective axes. [0004] In various embodiments, there may be included any one or more of the following features: the actuators having sufficient friction that any rotatable connections of the respective rotatable connections that are in positions having mechanical advantage above a threshold do not move when the actuators are not energized. The actuators may have sufficient friction that the arm remains still when the actuators are not energized regardless of the position of the arm. There may be a stepper motor controller connected to multiple actuators of the plural actuators, for driving the respective electric motors of the multiple actuators.

[0005] There is also provided a method of calibrating a robot arm as described above and including sensors to detect positions of the rotatable connections. The method includes selecting an actuator, moving the selected actuator into a default position or detecting that the selected actuator is already in a default position, selecting an additional actuator that has not yet been selected, moving the additional actuator into a default position or detecting that the additional actuator is already in a default position, and repeating the steps of selecting an additional actuator, and moving the additional actuator are detecting that it is already in the default position, until all of the actuators are in the default position.

[0006] There is also provided an actuator including an electric motor having a stator and a rotor, a sun gear, the rotor being connected to drive the sun gear, a pinion shaft mounted on the stator, a pinion gear mounted on the pinion shaft and arranged to mesh with the sun gear, and a strain gauge arranged to measure a strain of the pinion shaft or of a structure surrounding the pinion shaft. The actuator may be used in any suitable application including for example a robot arm as described above. There may be plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and the actuator further comprising plural additional gears each arranged to mesh with two of the pinion gears. There may be plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and a respective second pinion gear to form a compound gear, and the actuator further comprising plural additional gears each arranged to mesh with two of the second pinion gears. There may be a ring gear arranged to mesh with the plural additional gears, or directly with the pinion gear or gears where there are no additional gears. Any of the meshing gear teeth and

corresponding teeth on other gears may be tapered, one or more of the gears being biased axially to cause the tapered teeth to mesh more closely and reduce backlash. There may be a stepper motor controller connected to the electric motor for driving the electric motor.

[0007] These and other aspects of the device and method are set out in the claims.

BRIEF DESCRIPTION OF THE FIGURES

[0008] Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:

[0009] FFiigg.. 11 iiss a cutaway isometric view of a robot segment with an actuator and a 1 stage gearbox.

[0010] Fig . 2 is

[0011] Fig . 3 is

[0012] Fig . 4 is

[0013] Fig . 5 is

[0014] Fig . 6 is

[0015] Fig . 7 is

[0016] Fig . 8 is

stage gearbox.

[0017] Fig . 9 is

[0018] Fig. 10 is an isometric view of the robot segment of Fig. 7, with two floating gears removed.

[0019] Fig. 11 is an isometric view of the robot segment of Fig. 7, with two floating gears and a compound gear removed.

[0020] Fig . 12 is an isometric view of an embodiment of a cylindrical actuator.

[0021] Fig . 13 is a side view of the actuator of Fig. 12.

[0022] Fig . 14 is an end view of a first end of the actuator of Fig. 12.

[0023] Fig . 15 is an end view of a second end of the actuator of Fig. 12.

[0024] Fig . 16 is a side cutaway view of the actuator of Fig. 12. [0025] Fig. 17 is a closeup side cutaway view of the actuator of Fig. 12.

[0026] Fig. 18 is a closeup isometric cutaway view of the actuator of Fig. 12.

[0027] Fig. 19 is an isometric cutaway view of an actuator

[0028] Fig. 20 is an isometric cutaway view of the actuator of Fig. 19 as seen from a direction generally facing the first end of the actuator.

[0029] Fig. 21 is an isometric cutaway view of an actuator showing a strain gauge.

[0030] Fig. 22 is another isometric cutaway view of the actuator of Fig. 21.

[0031] Fig. 23 shows an exemplary robot arm.

[0032] Fig. 24 shows a control diagram for the robot arm of Fig. 23 ;

[0033] Fig. 25 shows an exemplary Scara base for use with the robot arm of Fig. 23;

[0034] Figs. 26A and 26B show stacks of actuators forming a joint for the robot arm of Fig. 23;

[0035] Figs. 27 and 28 illustrate exemplary actuators that may be used in the robot arm of Fig. 23:

[0036] Fig. 29 shows a detail of a hand control and arm control that may be used in the robot arm of Fig. 23;

[0037] Figs. 30A and 30B illustrate Scara configurations that may be used in the robot arm of Fig. 23 ;

[0038] Figs. 31 A and 3 IB show how manual actuators may be used in a variant of the robot arm of Fig 23:

[0039] Figs. 32A-32D show a first exemplary wedge design for use in the robot arm of Fig. 23;

[0040] Figs. 33A and 33B show a second exemplary wedge design for use in the robot arm of Fig. 23 ;

[0041] Fig. 34 shows a master slave configuration of robot arms, that may use robot arms as shown in Fig. 23 ;

[0042] Fig. 35 illustrates an angle between actuators in a wedge; and

[0043] Fig. 36 shows an actuator using sliding surfaces for producing friction to prevent backdrivability of the actuator. [0044] Fig. 37 is a plan view of an exemplary torque amplifier.

[0045] Fig. 38 is a perspective view of the torque amplifier of Fig. 37.

[0046] Fig. 39 is a closeup view showing a force on and meshing points of a floating gear of the torque amplifier of Figs. 37 and 38.

[0047] Fig. 40 is a schematic view showing a spring attached to a bearing as an alternative means to apply a force to a planet gear.

[0048] Fig. 41 is a closeup perspective view of an exemplary tapered tooth shape.

[0049] Fig. 42 is a cross section of the tooth of Fig. 41 at a narrow end of the tooth.

[0050] Fig. 43 is a cross section of the tooth of Fig. 41 at a middle portion of the tooth.

[0051] Fig. 44 is a cross section of the tooth of Fig. 41 at a wide end of the tooth.

[0052] Fig. 45 is a side view of a gear with teeth having a taper angle.

[0053] Fig. 46 is a perspective view of an exemplary gear having tapered teeth.

[0054] Fig. 47 is an axial view of the gear of Fig. 46.

[0055] Fig. 48 is a diagram showing various diameters of the gear of Fig. 46.

[0056] Fig. 49 is a diagram showing diameters and tooth side arcs of the gear of Fig.

46 at first ends of the teeth.

[0057] Fig. 50 is a diagram showing diameters and tooth side arcs of the gear of Fig.

46 at middle portions of the teeth.

[0058] Fig. 51 is a diagram showing diameters and tooth side arcs of the gear of Fig.

46 at second ends of the teeth.

[0059] Fig. 52 is a side cutaway view of an actuator having an electric motor and a torque amplifier as shown in Figs. 37-39.

[0060] Fig. 53 is a perspective view of a torque amplifier having magnets in outer planet gears.

[0061] Fig. 54 is a cutaway perspective view of a torque amplifier having springs attached to planet gears.

[0062] Fig. 55 is a flow diagram showing a method of calibrating a robot arm. DETAILED DESCRIPTION

[0063] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

[0064] The configuration disclosed here can be used with many different robot constructions. The configuration shown here is given as a non-limiting example.

[0065] Multiple wedges in a robot joint, as described in the section below entitled

"Wedge Robot" and shown in Figs. 23-36, allow increased payload for a given actuator size and torque because the rotating wedges increase the mechanical advantage of the actuators on the arm. This requires a larger number of actuators than a conventional robot, however, because multiple actuators are needed for each DOF. To implement a brake on every actuator could be a significant expense, as would an encoder and encoder read-head on each actuator if the robot is to be operated in closed-loop mode.

[0066] The cost of brakes and encoders will be justified in many applications. For applications where reduced cost is of high value, the following configuration eliminates the need for additional brake components and possibly the elimination of an encoder on every axis.

[0067] In an embodiment, a series of high torque motors such as a LiveDrive axial flux disk motor are paired with a torque amplifier such as the REFLEX gear reducer described in the section below entitled "Torque Amplifier" and shown in Figs 37-54.

[0068] Figs. 1-5 show an example axial LiveDrive motor paired with a single stage torque amplifier in a wedge 10 of a wedge robot.The motor and torque amplifier, and any other actuators disclosed in this document, may also be used in other applications than a wedge robot or any robot. A single stator/single rotor axial flux LiveDrive produces a high axial force which creates a relatively high load on the bearings 12. This bearing load remains relatively consistent regardless of whether the actuator is energized or not. This friction, in a LiveDrive axial flux device with 50Nm of continuous air-cooled output torque, may be around 7 Nm at all times. Increasing or decreasing of this bearing friction can be

accomplished by using different sizes or styles of bearings. Four-point contact thrust bearings, will, for example, have more friction than an angular contact bearing because the four contact points tend to "swirl" as they roll.

[0069] This bearing friction can be used to provide safe power-out operation of a low-cost robot as follows. Each actuator in an exemplary robot joint is paired with a low ratio torque amplifier such as, but not limited to, a 7.75: 1 reduction ratio gearbox. At 7Nm of bearing friction, in this example, the torque required to backdrive the motor/gearbox combination would be approximately 56Nm. This is very close to the continuous torque of the exemplary motor. If the motor was used on its own in the joint, it could provide the 56 Nm of continuous torque, but it would require air cooling and it would require an additional brake to prevent movement of the robot in a loss-of -power scenario. If a 7.75: 1 gearbox is used to amplify the torque of the LiveDrive, the driving torque of the motor is reduced by nearly 8X. A characteristic of this configuration that would be considered a detriment in many applications, can actually be used to the benefit of the robotic system as follows. The ordinarily detrimental characteristic is the high friction of the input motor bearings which uses more energy, and also reduces the backdrivability of the actuator. But while high backdrivability of a robotic actuator is often useful, there are many applications where backdrivability is not necessary. In this example, the ratio of the torque reducer is chosen to match the level of friction in the actuator such that the actuator can only be backdriven if the backdriving torque is greater than the desired holding torque of the actuator.

[0070] In this example, the 7Nm of motor bearing friction is multiplied by 7.75 and results in a required backdriving torque of around 54Nm. With a small percentage of gearbox friction, the torque to backdrive the actuator will be around 56Nm. This is the same as the air-cooled continuous torque of the motor, but in this case, no torque is required from the motor to hold a position because the bearing friction (multiplied by 7.75) is adequate. And while the bearing friction will consume energy, the energy required to overcome the bearing friction is only used when the actuator is spinning. This is in contrast to a low friction drive motor which requires a brake to be on at all times, which, in some duty cycle scenarios, would consume more power overall, even if the conventional fail-safe brake uses low power to stay disengaged. A brake component will also add weight to the system, so using the motor bearings to provide the safety-brake function, will further offset the extra power consumption by reducing the weight of the robot.

[0071] The friction may be sufficient to cause the arm to remain still when the actuators are not energized regardless of the position of the arm. Alternatively, the friction may be sufficient to cause the arm to remain still when the actuators are not energized in certain positions of the arm. The actuators have a point in the rotation where the mechanical advantage of force created by the actuators acting on arm movement is the lowest and where some movement can occur with minimal safety concern. Thus, the actuators may have sufficient friction that any rotatable connections that are in positions having high mechanical advantage do not move when the actuators are not energized.

[0072] Integrated gearbox

[0073] It is common in the motion control industry to couple a motor to a gearbox to increase torque. Embodiments of the present device provide for small size and light weight and narrow form factor as well as other benefits described below.

[0074] In an embodiment, one example of which is shown in Figs 1-5, an axial flux motor uses a high enough pole count that eddy current losses are reduced as a result of the thin posts and backiron. In this configuration, the solid structure of the stator which can be made out of a metal such as but not limited to, cast iron, which has the magnetic properties and also the structural stiffness and strength to allow it to support the forces created by the permanent magnets in the rotor, and also the forces generated by the integrated pinion gear shaft 20 which may be cast or machined into the back of the stator from the same monolithic material of the stator posts and backiron.

[0075] In this configuration, there is no need for a rotating planet carrier (although the structure to support this could be included). Instead, solid pinion shafts 20 (or pinion shaft receiving bores) are integrated into the backiron of stator 22. This allows a sun gear 14 or traction ring (not shown) to provide transmission torque to the planet gears 18 which, in turn, transmit this torque to the output gear 24 or a second stage of planet gears (shown in the embodiment of Figs. 7-11). Any number of reduction stages can be used as can many different types of gears. These include tapered gears that can be mechanically or magnetically axially preloaded to reduce or eliminate backlash.

[0076] An obvious drawback of this design, for some applications, is the relatively high friction in the bearings of the axial motor which results from the permanent magnet forces between the stator and the rotor. In applications where low friction is required, a second stator can be added on the other side of the rotor to balance these forces. In applications where a safety brake is required, in the event of a power failure, the friction in the axial motor bearings is used to prevent unwanted movement in the case of a power failure.

[0077] By integrating a gear or traction drive reducer into the back of the stator, a very high torque and low profile actuator is possible. At very high speeds, the eddy current losses may still become a limiting factor, but there are many robotic applications, such as cobots that interact with humans, where very high speeds are not required, and where an axial motor of this design with a low ratio gearbox will provide the required performance in a low cost and low profile package. An example of this is the wedge -joint robot described in the section below entitled "Wedge Robot" which would, in many applications move at relatively low speed as it assists a human on an assembly line or other application.

[0078]

[0079] In the example embodiment shown in Figs. 1-5, the single stage torque amplifier has a sun gear 14 connected to a rotor 16 of the LiveDrive motor and planet gears 18 rotatable about pinion shafts 20 that are connected to and may form part of a housing 30 that also mounts elements forming a stator 22 of the LiveDrive motor. The sun gear 14 meshes with the planet gears 18 to drive the planet gears. The planet gears 18 in turn mesh with a ring gear 24 to drive the ring gear. The ring gear is connected to a mounting bolt circle 26 on which a successive wedge of the robot arm may be mounted. The gears may have tapered teeth 28 and the planet gears 18 may be axially movable and axially biased to cause the tapered teeth to more tightly mesh. As shown in the figures, the housing 30 also houses the output bearing 32 which mount the ring gear 24 and mounting bolt circle 26 for rotation within the housing 30. [0080]

[0081] CONTROL SIMPLIFICATION

[0082] Cost reduction of a robot system is of significant value in many applications.

By pairing a high pole count motor such as the LiveDrive, with a torque amplifier, it is believed possible to create a high enough step count per motor rev that an open-loop stepper motor controller can be used instead of a closed loop control with an encoder. A 96 stator post LiveDrive with 92 rotor poles can have a step count per revolution of over 1000. When this is multiplied by 7.75, the number of steps per output revolution is over 8000 which means that each step is about 3 arc minutes. Using a single stator/single rotor axial flux motor provides friction in the motor bearings, with the advantage that motor will not jump to each new step, instead it must overcome the friction in the bearings, which may also be adequate to require a positive torque from the motor at all times allowing much finer resolution than just the 3 arc min. As a result, the cost and complexity of this system can be very low as a result of using stepper motor control input which does not require an encoder at each actuator.

[0083] Stepper motor operation also allows the use of a single stepper motor controller for multiple actuators in a wedge stack. In one exemplary configuration, every second wedge is wired in series such that they all respond to the same input current. Every first actuator could be on a separate driver or on the same driver wired in reverse so they rotate in the opposite direction. Alternately, a separate stepper motor drive on each actuator in a wedge assembly can be controlled by a single motion controller. In this case, individual actuators can be rotated during initial calibration by switching all the other actuators off. By using a single index sensor such as a Hall Effect sensor, in each wedge, it is possible to rotate one actuator at a time to find the index mark without moving the end effector through a full range of motion. In an example of how this could work, if the robot losses power, the motion controller would run the robot initiation procedure as follows. Each individual wedge in the base actuator would be rotated to the index position where the integrated bearing friction brake (or other brake mechanism) would keep it there. When each next wedge is rotated, the output will only move a fraction of the total output angle (depending on how many wedges in that joint) so there is minimal risk of damage being done to the robot, or payload, or operator.

[0084] Fig. 55 is a flow diagram showing a method of calibrating a robot arm, such as for example a wedge-based robot arm as disclosed in this document. In an embodiment, the method may be as described in the previous paragraph. The method starts in step 82. In step 84, an actuator is selected. In step 86, it is determined if the actuator is in default position. If it is not in default position, the actuator is moved in step 88. Depending on the embodiment, the actuator could be moved continuously until it is in default position, or it could be moved step-by-step which a check at each step as to whether the actuator is in default position. Once the actuator is in default position, in step 90 it is determined if there are any more actuators that have not yet been selected. If there are none, the method ends in step 92. If there are more actuators, in step 94 an additional actuator that has not yet been selected is selected. The steps 94, 86, 88 (if applicable) and 90 are repeated until all of the actuators have been selected and are in the default position.

[0085] In an embodiment, shown in Fig. 6 the index/home position of the base wedge actuators is at an angle that brings each of the actuators to a fully retracted home position such as the fully back position of the base wedge set of actuators as shown in Fig. 6. Fig. 6 shows a robot arm 40 with a base succession of segments 42, elbow succession of segments 44, and wrist succession of segments 46. The segments may be wedges 10 as shown in for example Figs. 1-5 or Figs. 7-11. The elbow 44 will retract to the fully bent position, one actuator at a time, and the wrist 46 will preferably return to an aligned

(straight/cylindrical) orientation (one actuator at a time) so the retraction of the robot from a random position to this retracted position will be reasonably predictable with minimal extraneous moment.

[0086] Figs. 7-11 show another embodiment of a wedge 10, using a two-stage gearbox. In this embodiment, instead of a single set of planet gears 18 as shown in Figs. 16, there are inner compound planet gears 50 and outer planet gears 52. The inner compound planet gears 50 comprise larger gears 54 which mesh with sun gear 14, and smaller gears 56 which mesh with outer planet gears 52. The outer planet gears 52 mesh with ring gear 24. The outer planet gears 52 may be floating in order to center themselves by three point contact with two inner planet gear smaller gears 56 and the ring gear 24.

[0087] A useful aspect of the REFLEX torque amplifier is the ability to eliminate backlash from the gear-train. This can be especially relevant in a configuration such as the wedge joint robot where a large number of actuators are connected in series. Embodiments of the REFLEX eliminate backlash with a mechanically or magnetic axial preload on a train of tapered gears. In the embodiment shown in Figs. 7-11, the gears may have tapered teeth 28 and there may be magnets, a bolt, or another mechanism to deliver axial load to the floating gears 52. In the embodiment shown magnets 58 are shown embedded in floating gears 52. The magnets 58 may attract corresponding magnets (not shown in these figures) in the housing 30. More details are described below in the section entitled "Torque Amplifier".

[0088] Another feature of an embodiment of the REFLEX torque amplifier is the ability to measure torque output with high sensitivity. This feature is available to the REFLEX because it does not use a rotating planet carrier. This feature is made practical by the high torque of the LiveDrive motor which only requires a low ratio speed reducer for high output torque. A rotating planet carrier is typically used to increase the reduction ratio, but in the case of the LiveDrive plus REFLEX, a single stage reduction of 2: 1 up to 5: 1 is possible or a two stage reduction of from 4: 1 to 10: 1 is possible (with higher and lower ratios possible - as well as additional stages being possible). As a result the REFLEX uses a fixed first stage of gears (18, 50) that has a fixed pinion shaft 20 attached to the housing 30.

Because this pinion shaft is fixed instead of spinning in a planet carrier, the strain on this shaft can easily be measured with a stationary strain gauge. A strain gauge can also be used to determine torque by measuring strain of a structure surrounding the pinion shaft where transmitted torque results in a predictable and measurable distortion. The higher the output torque, the higher the strain on this shaft 20, so the strain gauge measurement will be proportional to the torque output of the actuator.

[0089] This direct torque measurement through the gear train allows proprioceptive sensing for robotic control. It also allows the motor driver to know how much torque is required from the motor. This is especially useful in a stepper motor drive configuration such as that described above, because the stepper motor driver can keep the current at a level which uses the lowest possible power without allowing the stepper to skip a step. The motor control can, therefore, be dramatically simplified as compared to a servo feedback control because no encoder or feedback loop programing is required. Instead, the driver compares the output torque as determined by reading the strain gauge(s) and sets the current to whatever is necessary to hold or cause movement but without sending a greater current level or total electrical power to the motor than necessary.

[0090] A strain gauge can be included in any of the gearbox embodiments shown in this document and is specifically illustrated with respect to the embodiment of Figs. 12-22 as described below.

[0091] The result, when these things are combined in an exemplary wedge -bot configuration is a low cost robot with very high payload and the safety of an integrated braking mechanism.

[0092] Figs. 12-22 show an embodiment of a motor and gearbox combination forming an actuator 60. This embodiment of an actuator 60 is not shown as part of a wedge segment of a robot arm, but could be used in such an arm, for example multiple such actuators could be attached end-to-end with shims to form wedges. A first end 62 of the actuator 60 houses the motor, which in this embodiment is a radial LiveDrive 72, and a second end 64 of the actuator 60 houses a gearbox, a housing 66 of the second end 64 rotating with the ring gear 24 and rotating with respect to the housing 68 of the first end 62 when the actuator is in motion. The gearbox in the embodiment shown is a two stage gearbox as described in relation to the embodiment of Figs. 7-11. A cap 70 connects to first end housing 68 and extends over the sun gear 14

[0093] The radial LiveDrive 72 comprises an outer stator 74 connected to the first end housing 66 and an inner rotor 76 connected via a connector 78 to drive sun gear 14.

[0094] Fig. 14 shows an end view of the actuator 60 from the first end and Fig. 15 shows an end view of the actuator 60 from the second end. Fig. 16 shows a side cutaway view and Fig. 17 shows a closeup of the view of Fig. 16. In Fig. 16-18, strain gauges 80 can be seen in housing 68 at base portions of pinion shafts 20. Fig. 19-20 show an embodiment not including strain gauges. Figs. 21-22 show another embodiment including strain gauges 80.

[0095] Wedge Robot

[0096] A robot arm comprises multiple links connected by actuators and extends between ends, such as an end effector and a base. Upstream of an element on the robot arm means closer to the base than the element. Downstream of an element on the robot arm means closer to the end effector than the element.

[0097] A link is a part of a robot arm that extends between actuators or between an actuator and the end of a robot arm. The robot arm may work in cooperation with an operator who controls the operation of the robot arm but bears no load. All load may be taken by the robot arm. A robot arm may include a wrist joint, which may be the joint closest to the end effector. A robot arm may include a shoulder joint, which may be the first joint capable of providing lift in the robot arm, nearest to the base of the robot arm. An elbow joint may be a joint between the shoulder and the wrist joint. A forearm or link may be a part of the robot arm between the wrist joint and elbow joint, or between the wrist joint and the shoulder joint. The forearm may be the closest part of the robot arm to the wrist joint.

[0098] The actuators may be formed by electric machines, such as an axial flux electric machine. The actuators may be hollow. The actuators may each have a stator and rotor that are integrated with, or directly attached to, adjacent links of the robot arm.

[0099] The links of the robot arm may be hollow and may have any suitable shape.

Where at least one of the links is connected by at least one of the actuators, the stator or rotor of the actuator may be connected to a first link and the other of the stator or rotor may be connected to a second link. A straight link is a link that extends between actuators having parallel or co-linear axes. An inline link is a link that extends between co-axial actuators.

[0100] An end of the robot arm may include the end effector. The end effectors include, but are not limited to an end effector with three fingers for gripping objects.

[0101] Another end of the robot arm comprises a base or other point of reference.

The base may be fixed to a surface of an object. The object may be a fixed object or a moving object including, but not limited to, a wall, a roof, a floor or another structural element, or a wheeled vehicle.

[0102] The robot arm may be operated by a human operator by means of a control device, such as a hand control. The hand control is a device that may be operated by a person's hand to produce control signals corresponding to movement of the robot arm. The hand control is an object shaped to be gripped by the human hand including, but not limited to, a ball, a disk, a handle, a rod, a pedestal or other shaped object that may be gripped by the human hand. The hand control may have multiple degrees of freedom and may include x-y-z translation and rotation about x-y-z axes. Where x-y-z translation is present, x-y may define a horizontal plane while the z axis is vertical. The x axis may correspond to forward and backward movement in relation to the operator, while the y axis may correspond to side to side movement in relation to the operator. Lifting up on the hand control may correspond to movement along the vertical axis. Rotation about the x-y-z axes may correspond to rotation about virtual x-y-z axes that pass through the center of the hand control. The hand control may include additional controls such as a rotary element that encircles a base of the hand control and that provides an additional rotation signal. The hand control may be provided by dual controls that are separated and operated by different hands. For example, one of the dual controls forming the hand control may provide signals corresponding to translation, while the other may provide signals corresponding to rotation. Additional controls may be provided on the hand control such as buttons and levers to provide additional functions. The hand control and additional controls may be provided on a console that is attached to the robot arm. The hand control may comprise a 3D mouse made by 3DConnexion of Boston, Massachusetts, USA, though other hand controls may be used. Details of the hand control are not supplied since such hand controls are known in the art of 3D manipulation of virtual objects.

[0103] The acronym SCARA or Scara means Selective Compliance Assembly Robot

Arm or Selective Compliance Articulated Robot Arm. A Scara is rigid in the Z-axis and pliable in the XY-axes. By virtue of its parallel-axis joint layout, the Scara is slightly compliant in the X-Y direction but rigid in the 'Z' direction, hence the term: Selective Compliant.

[0104] An end of a robot arm may comprise a base or end effector. A wedge is defined as a part of robot arm that terminates at opposed ends with rotary actuators, where the rotary actuators have rotation axes that are not co-linear. In some embodiments, the rotation axes of the rotary actuators are not co-planar. In some embodiments, the rotation axes are co-planar and offset from 0 degrees to 90 degrees. In some embodiments, the offset may be 1-10 degrees or 1-5 degrees or 1-2 degrees. Each wedge extends between wedge ends and is bounded by a stator or rotor of respective actuators on each end of the wedge. Each actuator has an axis of rotation and axes of actuators at the end of each wedge are at an angle to each other that defines the wedge angle of the wedge. A stack of actuators may form a joint. Each joint may be operated independently from other joints, or may be operated in unison.

[0105] A robot control system may comprise one or more controllers, such as a computing device that may accept control inputs and provide control outputs, and a driver or drivers. The control system receives control signals from the hand control. In some embodiments, for example where there is a one to one correspondence between control signals from the hand control and the actuator, or a set of actuators, driven by a single driver, the controller need only route signals and condition signals so that they may be read by the drivers and to provide proportional signals to the actuators that are controlled in series. The proportions for actuators in series may be stored in a lookup table for fast response. The controllers may comprise general or specific purpose processors with memory, a human interface and display(s).

[0106] In some embodiments, where feedback is provided by a force transducer, some more complicated functions may be provided for example using a comparator to decide whether the force exceeds a threshold and generating a stop command to all actuators. In other embodiments, where safety mechanisms are in place, the controller may also sense movements that are beyond a threshold and stop or slow down the actuators. Safety regulations should be taken into account in operation of the robot arm. For example, in jurisdictions where certain types of robots can only be operated where no human is in the robot envelope, then it may not be possible to use a hand control on the robot arm and a master - slave or remote control will be required, possibly with haptic feedback for the operator.

[0107] The driver is any suitable driver for the corresponding actuator. Drivers are well known in the art of electrical machines.

[0108] Referring to Fig. 23, there is shown a simplified view of a robot arm 1010.

The robot arm includes a Scara unit 1012 having a fixed base Bl, and an arm 1014 secured to a mobile end B3 of the Scara unit 1012 by a shoulder joint SI. Each joint SI, El and Wl comprises multiple wedges 1018. The wedges 1018 each comprise a portion of a robot arm and terminate at each end in a part of an actuator 1048 symbolized by a line between wedges 1018. Each actuator 1048 comprises a part (rotor or stator) on one wedge 1018 and another part (rotor or stator on an adjacent wedge, or other part of the robot arm.

[0109] In this example, the arm 1014 includes an elbow El, a first wrist Wl, and there may also be a second wrist at location 1021, and an end effector 1016. A hand control 1020 may be located upstream of wrist Wl but downstream of location 1021, and therefore downstream of a second wrist, if present. An arm control 1022 may also be located with the hand control 1020. The hand control 1020 and arm control 1022 may be used

simultaneously by an operator to control the robot arm. When the hand control 1020 is located between actuators, the actuators between the hand control 1020 and the base Bl may be referred to as upstream actuators and the actuators between the hand control 1020 and the end effector 1016 may be referred to as downstream actuators. In an example, the upstream actuators may all be controlled by hand control 1020 or arm control 1022 operation to change the rotation speed of the upstream actuators (speed control), and the downstream actuators may all be controlled by hand control or arm control operation by angle to angle control. The Scara arm 1012 may be replaced by a linear actuator or actuators or a telescoping arm. If a linear actuator is used, it may follow the design shown in Fig. 27 or Fig. 28, except with the device being linear rather than rotary. [0110] In speed control, the degree of operation of the hand control 1020 or arm control 1022 causes the corresponding actuator to rotate at a speed that is proportional to the degree of operation. In angle control, the degree of operation of the hand control 1020 or arm control 1022 causes the corresponding actuator to move through an angle that is proportional to the degree of operation of the hand control. The operation of the hand control 1020 or arm control 1022 may comprise a displacement of the hand control 1020, a force applied to the hand control 1022, or a rotation of the hand control 1020. The proportional relationship between the operation of the hand control 1020 and the speed or angle of rotation of an actuator being controlled by the hand control 1020 may be set by the user using controls on the controller 1024. For the determination of proportional movements, a lookup table stored in the controller 1024 may be used.

[0111] Referring to Fig. 24, there is shown a control diagram for the robot arm of

Fig. 23. In practice, the hand control 1020 may be mounted on the robot arm, for example between wrists, and produces control signals corresponding to a movement or force applied to the hand control. For example, translation along an x, y or z axis may produce translation control signals Tx, Ty and Tz, and rotation of the hand control about an x, y or z axis may produce rotation control signals Rx, Ry and Rz. In some applications, if only translation is required, then only translation signals are used. Correspondingly, where only rotation is required, only rotation signals are used. The control signals are provided along conventional communication channels denoted by the line 1026 leading to controller 1024. The communication channels may be wired, optical, wireless or any other suitable

communication channel and may be entirely physically located within the hollow interior of a robot arm. An additional dial, button, lever or other control element such as a ring around the base of a hand control, may be used to provide an auxiliary signal which may be used to generate an auxiliary control signal for sending to the controller 1024. There may be additional such control elements with corresponding additional auxiliary control signals. For example, an arm control 1022 may also be secured to robot arm between wrists by a pivot or gimbal. The arm control 1022 may pivot about an x axis and a y axis at the gimbal. The operator's arm may rest on the arm control 1022 while the operator is also holding the hand control 1020. Movement of the operator's elbow up or down may cause a pivot of the arm control about the y axis, while movement of the operator's elbow laterally may cause a pivot of the arm control about the x axis. Further auxiliary controls may be included, such as for example a device to send a control signal to the end effector 1016 to open or close. The control may also be simplified as described in the section 'Control Simplification".

[0112] The controller 1024 conditions and routes signals to the drivers 1028, labelled drivers 1 through N, and any others that may be present with for example a one to one correspondence between the control signals and the drivers. In some instances, there may be a many to one correspondence between control signals and drivers, but the controller integrates (subtracts or adds) the many control signals to yield a single control signal to each driver.

[0113] The input to the controller 1024 may be a multi-axis input device that the operator grasps. The following describes an embodiment where the input device has 6 axes, three translational (x,y,z) and three rotational (roll,pitch,yaw). In this embodiment, the input device may be a hand control 1020 such as a 6-axis joystick. Other embodiments may have differing number of axes (eg. three translational plus one rotational). Input devices such as multi-axis joysticks are well known and commercially available. The input device may be mounted on the robot itself. The mounting location in this embodiment is near to the end effector, but upstream or behind the wrist Wl.

[0114] When the operator deflects the input device, the robot joints upstream of the input device activate in a coordinated manner to move the end-effector with a velocity. The velocity is characterized by a magnitude (speed) and a direction of movement. The speed that is generated by the actuators increases in proportion to the magnitude of the deflection of the input device from its zero-position. The direction of the velocity generated by the actuators (more or less) corresponds to the direction that the input device is deflected relative to the mount of the input device.

[0115] When the user rotates the input device, the robot joints downstream of the input device may activate in a coordinated manner to orient the end-effector so that the orientation of the end-effector has a direct one-to-one or proportional angle relationship with the orientation of the input device. That is, an angle change of 1 degree of the handle will result in a 1 degree rotation about a parallel axis of the end effector when in 1 to 1 mode. If in proportional mode, as selected by the operator, the end effector will rotate by a greater degree or a lesser degree but will stop rotating when the handle stops rotating.

[0116] Since the base of the input device 1020 moves with the robot (because it is attached to the robot) whereas the operator is standing on the ground, the deflection and rotation of the input device will change dynamically as the robot moves. Since the translation of robot is in the direction of the deflection of the input device, the motion of the robot will tend to cause the deflection of the input device to diminish, unless the operator moves the input device yet further in that direction. This essentially creates a feedback loop that will move the robot in any direction desired by the operator, and stop the robot when the input device is returned to its zero-positon.

[0117] The motion of the robot is related to the deflection and rotation of the input device as explained in the foregoing paragraphs. To effect that relationship, a control system converts the input device signals to electric currents that cause the actuators 1048 to move.

[0118] The control system comprises controller 1024. The controller 1024 has inputs from the input device 1020. These may be analog inputs or digital inputs, depending on the input device. The controller 1024 has inputs 1034 that read in the position and/or velocity of the actuators 48. In the embodiment shown, these inputs are from the servo drivers 1028. In alternative embodiments (not shown) the inputs may come directly joint sensors mounted on the robot or on the actuators 1048.

[0119] The controller 1024 has internal logic. Based on the input from the actuator positions 1034 the internal logic determines what the angles of the robot joints are at that moment. The internal logic then determines, based on the deflection and rotation of the input device and angle of the joints, what the desired actuator positions and velocities. The embodiment of the internal logic described herein may implement simple translation of the input device inputs into robot motions, such as the input causing equal and opposite motion of actuators. This embodiment provides for motion of the end effector in a direction that is nearly (but not exactly) in the same direction as the deflection of the input device. In alternative embodiments, the internal logic may comprise an algorithm based on inverse kinematics of the robot, in which case the motion of the end effector may follow more precisely the deflection of the input device. Internal logic of controllers is well known. For example, US6140787 provides one implementation of internal logic.

[0120] The controller 1024 has outputs 1036, one for each actuator 1048. The outputs are signals that indicate the desired position and velocity for each actuator 1048.

[0121] Servo drivers are well known and commercially available from many vendors

(for example the Elmo Gold servo product line, commercially available from Elmo). The control system comprises a plurality of servo drivers 1028, one for each actuator 1048:

[0122] Each servo driver has an input 1036 from the controller that sets the desired velocity and position of the actuator 1048. Each servo driver has an input 1037 from the actuator that indicates the actual actuator position.

[0123] Each servo driver has an output 1034 that communicates the actual joint position and velocity to the controller 1024. In general, while the robot is in motion the actual position and velocity of the joint will not be the same as the desired position and velocity.

[0124] Each servo driver 1028 has a servo control circuit that uses a well known PID

(position-integral-derivative) loop to generate an electrical current 1038 to drive the actuator. In alternative embodiments, the servo driver 1028 may comprise logic and software that implement other types of servo control algorithms. Design and implementation of servo drivers is well known, and many alternative embodiments are available to implement this component.

[0125] In alternative embodiments (not shown) the controller 1024 is divided into several simpler controllers that each provide a subset of the functionality described in the foregoing, eg. one controller for the SCARA and another for the wedge actuators. In another embodiment (not shown) the function of the drivers 1028 is incorporated into the controller itself and the output of the controller may directly activate the actuators 1048. In another embodiment (not shown) the actuators may be stepper motors, in which case the feedback from the actuator to the servo driver may be eliminated. The architecture and design of alternative control systems is well known in the art, and there are many ways to implement the control system.

[0126] If the actuators 1048 are rotary actuators they may all rotate in the same direction or alternating actuators may rotate oppositely, so a first actuator in a stack of wedges in a joint may rotate clockwise, then a second actuator may rotate counterclockwise, then a third actuator may rotate clockwise and so on. A first wedge (a section of the robot arm that is between two actuators that are at an angle to each other) and a last wedge in any array of four or more actuators that moves in unison are preferably half the angle of the rest of the wedges, in terms of the angle of their plane of rotation relative to an adjacent wedge, to prevent the robot arm 1010 moving out of plane. When a pair of wedges counter rotate three actuators may need to move to prevent unwanted rotation of the robot arm 1010.

[0127] The actuators 1048 may be driven proportionally to the magnitude of the control signals either in terms of speed control or angle control. Drivers 1-4 may be connected to drive the actuators Al through A4 in the Scara 1012 by speed control. As shown in Fig. 25, in the Scara 12, the actuator Al is located above a structure contacting element or base B 1 such as a pad that is connected via any suitable means to a surface of an object, for example a structure such as a floor, wall or ceiling, or the ground or a vehicle of any kind. A first link LI is rotated by the actuator Al about a vertical axis. At an opposite end of the first link LI to the actuator Al, the actuator A2 connects to a second link L2 that rotates around a vertical axis of the actuator A2. The first link LI may also be supported by the surface of the object through a pad or base element B2. Likewise the second link L2 is connected to a third link L3 by the actuator A3 and the third link L3 rotates relative to the second link L2 about the vertical axis of the actuator A3. There may be two or more links LI etc in the Scara arm. In this instance, there are three links and the third link L3 connects to a shoulder S 1 through the actuator A4. The shoulder S 1 may rotate relative to the third link L3 about a vertical axis of the actuator A4. The third link L3 may also be supported on the surface of the object by base B3.

[0128] The base Bl may be fixed to the surface of an object, for example a floor.

Base B2 and B3 may comprise a bearing element, for example as formed by a low friction surface, which could be a sliding surface or a surface of a rolling element such as a roller bearing. The axes of the actuators Al, A2, A3 etc are all parallel, which causes the links LI, L2, L3 to move in a plane perpendicular to the axes and the bearing element to move along the surface. Depending on the motion of the actuators Al, A2, A3 etc, the end of the Scara 1012 may translate or rotate in an arc. For translation, the actuators Al, A2, A3 etc rotate alternately oppositely. The bases B2, B3 assist in supporting the robot. In general, link LI forms a base link, and link L3 or one of a chain of links forms an end link. Links between the base link and the end link form intervening links. Adjacent links are connected by actuators having parallel axes. Motion of the actuators causes the links to move in a plane extending away from the base. The bearing element may be on the first link, the end link or one of the intervening links.

[0129] Drivers 1028 may drive the actuators Al through A3 or the actuators Al through A4 to rotate in unison with the actuator Al and the actuator A3 rotating one way, for example clockwise, and actuator A2 or actuator A2 and actuator A4 rotating the other way or counterclockwise. If the actuators Al though A4 are stepper motors then the power commands may comprise power on for a set number of steps for each of the stepper motors in a given period of time. This causes the actuators Al through A4 to rotate at the same speed. If it is desired that the speed of the stepper motors be different, so that they rotate different amounts in a given period of time, then each actuator may be a different size or have a different number of steps so that a given command to rotate a specific number steps results in a different rotation angle. The actuators Al through A4 rotate so long as the hand control provides control signals through the controller 1024 to the drivers 1028. With electrical actuators, the time for the actuator to reach a speed set by the position of the hand control 1020 is normally so short in relation to the time it takes for an operator to move the hand control 1020 that the speed response is essentially instantaneous. The operator may not notice the acceleration.

[0130] The hand control 1020 may be provided with a spring (not shown, but common in 3D controllers) that returns the hand control to neutral (no outgoing control signals). When the hand control 1020 returns to neutral, all actuators stop. An example of the hand control 1020 may be formed of a normally vertical tube that rotates and translates relative to a ball at the center of the vertical tube with springs on all axes including translation axes.

[0131] When the hand control 1020 is translated or a force is provided in the y direction, the drivers 1028 may provide a different set of speed control power commands to the actuators Al through A4 so that the actuators Al through A4 rotate either more clockwise or counterclockwise so that the actuator A4 at the end of the Scara 1012 tends to move right or left relative to a point of view looking out from the base Bl of the Scara 1012 outward along the Scara 1012. For each of the shoulder SI, an elbow El, and the wrist Wl or wrist W2, there may be any number of actuators, for example four to ten, but could be more.

[0132] When the hand control 1020 is translated or a force applied in the z direction

(vertical), the hand control generates z translation control signals through the controller 1024 to the drivers 1028 which send drive signals to the shoulder joint SI or the elbow joint El, if present, and the wrist joint Wl. Each of the shoulder joint SI, or the elbow joint El if present, and the wrist joint Wl have one of the actuators or one of the sets of actuators, the effect of which is to cause rotation about a horizontal axis and therefore lift or lower the end effector end 1016 of the robot arm A in the z plane. Shoulder joint S 1 or elbow joint El may comprise a single actuator with a horizontal axis or may be formed of multiple actuators.

[0133] In the case where the shoulder joint SI comprises multiple actuators, the actuators may be at an angle to each other. The angle may be for example non-zero and less than forty-five degrees (45°). Each link between the actuators 1048 in the joint SI therefore becomes a wedge joint with a short side and a long side. When the actuators are rotated so that all the short sides are on the same side, the robot arm 1010 is bent concave in the direction of the short sides. By rotating all the actuators 1048 up to 180° in unison with alternating actuators 1048 rotating in opposite directions, the shoulder joint S I goes through a point where all the actuators 1048 have rotated 90° and the joint is vertical, to a point where the actuators 1048 have all rotated up to 180°. The effect of this rotation is to raise or lower the effector end 1016 of the robot arm 1010 relative to the first actuator in the shoulder joint SI (or the actuator A4 in the Scara 1012) depending on the degree of movement or applied force of the hand control in the z direction. The first wedge and last wedge in any array of four or more actuators that moves in unison may be half the angle of the rest of the wedges to prevent arm moving out of plane.

[0134] For example, there is shown in Fig. 26 A and Fig. 26B a portion (wedge bot) of a robot arm with a base plate 1040 and being formed in this instance of ten wedges 1042. To keep the robot arm in plane, the bottom wedge 1044 and top wedge 1046 need to be half the angle of the other wedges. In the example shown, ten wedges are used at 10° each. The first and last wedge are 5°. Each wedge 1042, 1044 and 1046 may be formed as shown in Figs. 32A, 32B, 32C, 32D, 33A and 33B.

[0135] If the top wedge and bottom wedge are not half angle, the robot arm 10 stands skewed. The following table shows the direction of rotation and the angle of rotation for each wedge for an example operation of a robot arm.

[0136] In Fig. 26A, the thin end of the wedges 1042 are all aligned so that the wedge stack is maximally bent in one direction. The first and last wedges have half the wedge angle of the intermediate wedges. If all wedges 1042 are rotated 180 degrees, alternating wedges oppositely, the wedge stack goes through an intermediate position shown in Fig. 26B where all wedges 1042 have rotated oppositely pairwise 90 degrees (each odd rotates clockwise for example, and each even wedge rotates counter clockwise for example) and the stack is vertical, to a position where all wedges 1042 have rotated 180 degrees and the thin ends of the wedges are oriented oppositely to the position shown in Fig. 26A so that the stack bends maximally in the opposite direction.

[0137]

[0138] If each of the actuators in a joint is at a low angle, for example one degree relative to an adjacent actuator, then when the actuator rotates 180°, the actuator only lifts the robot arm a little, thus providing a mechanical advantage. The more actuators, the lower the angle, then the greater the mechanical advantage. This advantage applies with best effect when the robot arm is located in the plane defined by the aligned shortest sides (0° point) and aligned longest sides (180° point). The greater the deviation of robot the arm from this plane, the greater the loss of mechanical advantage. Additional hand adjustable wedge joints 120, 122 may be provided in the robot arm, for example next to any of the sets of actuators, the elbow El or the wrist, on both sides, to allow the operator to manually locate the robot arm as shown in Fig. 9A and 9B without using the electric actuators at an inefficient angle.

[0139] The elbow El may be controlled in like manner to the shoulder SI by the driver 1028 with all of the actuators 1048 in the elbow El rotating in unison up to 180° to effect a lifting action in response to a power command from the controller 1024. The actuators 1048 in the elbow El may alternate in rotation directions. The degree of rotation controls the amount of lifting or lowering. The first wedge and last wedge in any array of four or more actuators that moves in unison must be half the angle of the rest of the wedges to prevent the robot arm moving out of plane.

[0140] The wrist Wl may be controlled in like manner to the shoulder S 1 with all of the actuators 1048 rotating in unison up to 180° to effect a lifting action in response to power commands from the controller 1024. The actuators 1048 in the elbow 1028 may alternate in rotation directions. The degree of rotation controls the amount of lifting or lowering. There may be any number of actuators in the wrist Wl. In an embodiment, the hand control 1020 is located between the wrist Wl and a second wrist joint.

[0141] For rotation control about the x, y or z axis, angle to angle control may be used. In angle to angle control, a rotation of the hand control 1020 generates a rotation control signal that is proportional to the angle rotated by the hand control 1020. For each of axes x, y and z, this signal is provided to the controller 1024, which routes and conditions control signals for the drivers 1028. One of the drivers 1028 may respond to an x axis rotation of the hand control 1020 (twist hand like turning key in lock) and send a power command to a horizontal axis actuator on the end of the wrist Wl, which causes an angle to angle rotation about a horizontal axis of the robot arm at the end of the wrist Wl and therefore the end effector 1016. The controller 1024 may respond to y axis control signals (motorcycle throttle motion) to send angle to angle drive signals to the actuators 48 of the wrist Wl to effect an effective rotation of the wrist Wl about a horizontal side to side axis. This motion tends to lift and raise the end effector 1016 as well. This y axis angle rotation command may cause each second actuator in wrist Wl to rotate in the same direction, but each other actuator 1048 to rotate in opposite directions by the same amount. Having the rotation by the same amount causes the actuators 1048 and the payload to remain on plane and reduces torque on the actuators.

[0142] If the operator uses the hand control 1020 and by so doing maintains the robot arm 1010 at the hand control 1020 vertical, then a first downstream actuator from the hand control at wrist Wl may be used to rotate the end effector around a vertical axis.

[0143] For rotation of the end effector about the x axis, a horizontally oriented actuator 1048 may be driven by a respective driver 1028 to rotate a specific angle. For rotation about the z axis, a vertically oriented actuator 1048 may be driven to rotate about a specific angle. For rotation about the y axis, multiple actuators 1048 of the wrist Wl may be caused to rotate in unison up to 180°.

[0144] For improved dexterity and lifting capacity, the shoulder SI may move about a horizontal axis as shown in Fig. 23 (in this figure, horizontal corresponds to a line through the center of the actuator stack that extends perpendicularly to the page). That is, the actuators in S 1 may rotate in unison 180° alternating clockwise and counterclockwise, to cause an effective rotation of the arm about a horizontal axis and therefore a lifting of the robot arm. The first wedge and last wedge in any array of four or more actuators that moves in unison must be half the angle of the rest of the wedges to prevent the robot arm moving out of plane. For improved dexterity and lifting capacity, the elbow El may move about a horizontal axis as shown in Fig. 23 (in this figure, horizontal corresponds to a line through the center of the actuator stack that extends perpendicularly to the page). That is, the actuators in the elbow El may rotate in unison 180° alternating clockwise and

counterclockwise, to cause an effective rotation of the arm about a horizontal axis and therefore a lifting of the robot arm. The robot arm at the hand control may be maintained vertical at all times to reduce operational complexity. The wrist W 1 may move

proportionally to the elbow El and the shoulder S I so the axis of an actuator 1048 at the wrist Wl will remain near vertical.

[0145] A user forearm attachment 1022 can be used to control the angle of the forearm 1032 about a vertical, z axis, and horizontal y (motorbike throttle) axis. This may be an angle displacement = angle speed response where a sideways angle of the forearm rest 1022 (about a vertical axis) will result in the shoulder vertical axis rotating in one direction (and preferably that one or more other Scara axis rotate in opposite directions) so the non- Scara arm rotates around the user to achieve a different angle (about a vertical axis) of approach to the payload.

[0146] Rotation of the user-forearm rest 1022 about a throttle axis may result in the elbow El and shoulder S I rotating about a horizontal axis, but in opposite directions so the robot forearm (the arm between the elbow El and wrist Wl) can be controlled by the operator to be more vertical or more horizontal. In this way, the angle of the robot forearm will follow the angle of the operator's forearm. The wrist Wl angle will be doing its job as stated above, of keeping the top of the wrist in a vertical axis attitude.

[0147] One way to control stacked actuators, where the actuators in the robot arm are separate by wedges, as for example as shown for the shoulder S I, the elbow El and the wrist Wl, is as follows. The respective axes of consecutive actuators may be offset relative to each other by a few degrees such as 1° to 10°, 10° to 20°, or 20° to 30°. Thus the wedges turn angles of like amount. Actuators are operated in pairs. The pairs may comprise consecutive actuators or they may be separated. The initial position of the actuators may be taken as the zero position, where all shortest sides of the wedges are aligned as shown in Fig. 26A. Degree of rotation is measured from the zero position. Rotation of 180° corresponds to a half rotation of any one of the actuators. If all of the actuators rotate 180°, then all of the actuators will be aligned with the shortest sides of the wedges aligned at 180°. The actuators have the greatest mechanical advantage when they rotate near 0° or 180°, for example 0° to 20°, referred to as initial rotation or 160° or 180°, referred to as final rotation.

[0148] To effect a lifting movement, all of the actuators in a joint may initially be 0° for example as shown in Fig. 26A. In this process, all pairs are moved with actuators of the pair rotating in opposite directions. All of the actuators may be rotated through an initial rotation to a position I with actuators of any pair rotating oppositely so that the robot arm remains approximately on plane. The actuators are then rotated one or a few pairs at a time from the position I to a position F, corresponding to where the final rotation starts. During the rotation of one or a few pairs at a time from I to F, the remaining actuators rotate back to zero or close to zero degrees. The remaining actuators then rotate pairwise back to position I. This process (one or more pairs of actuators are taken from I to F while the remaining that have not gone from I to F go to zero or close to zero, and then the remaining pairs are rotated back to position I) may be repeated until all actuators are at the position F, then all actuators may be rotated pairwise from position F to or near to one-hundred eighty degrees.

[0149] Fig. 27 shows an exemplary axial flux actuator 1052 in a configuration useful for use in a Scara configuration in particular, where the actuator 1052 has an axis perpendicular to the arms 1054 and 1056. The arms 1054 and 1056 may be any of the arms of a robot arm in some embodiments. In an embodiment of a joint that has an actuator with a rotation axis perpendicular to the robot arm, one or more actuators 1052 may be used that are coaxial to each other. Depending on the embodiment, the actuator 1052 may be used for any of the disclosed Scara, shoulder, elbow or wrist joints. In particular, in a mode of operation of the robot arm such that the hand control operates to control upstream actuators differently than downstream actuators, for example when upstream actuators are controlled using position of hand control to velocity of actuator control and downstream actuators are controlled using position of hand control to angle of actuator control, the actuators being controlled may have the configuration of Fig. 27.

[0150] Fig. 27 shows more detail of an exemplary design of an axial flux actuator

1062 that may be used for any of the actuators in the robot arm, including the axial flux actuator 1052. In Fig. 28, two arm members or links 1064 and 1066 are connected by the axial flux motor 1062. The arm members or links 1064, 1066 may be part of any of the wedges or other parts of the robot arm 1010 or part of the links in the Scara 1012. Actuator 1062 may have a stator 1072 attached to the link or arm 1066 such as with bolts and/or adhesive and/or thermal fit or by being formed integrally with the arm. A rotor 1074 is attached to a link or arm 1064 such as with bolts and/or adhesive and/or thermal fit or by being formed integrally with the arm. An outer bearing 1076 and an inner bearing 1078 allow relative rotation of the stator 1072 and rotor 1074 and provide precise relative axial location of the stator 1072 and rotor 1074 to maintain an airgap of a desired gap between the stator posts 80 and rotor posts that hold magnets 1082 and that provide a flux path for the magnetic fields provided by the magnets 1082. The rotor 1074 may have flux restriction holes 1084. The use of the inner bearing 1078 inside the inner diameter of the airgap and the outer bearing 1076 outside the outer diameter of the airgap distributes the attractive forces between the stator 1072 and rotor 1074 between two bearings for longer service life and/or lighter bearings. The use of inner diameter bearings 1078 and outer diameter bearings 1076 also reduces the mechanical stress on the stator 1072 and rotor 1074 to allow a thinner cross section and lighter weight, for example as is possible with the high pole count of embodiments of the device.

[0151] The axial magnetic attraction between the stator 1072 and rotor 1074 which results from the permanent magnet flux in the rotor 1074 provides axial preload on the bearings 1076, 1078. It has been shown by analysis and experimentation that with high strength magnets such as but not limited to neodymium N52 magnets, this axial force is adequate to keep the bearings 1076, 1078 preloaded in the stator 1072 and rotor 1074 and to provide adequate axial force to allow the links 1064, 1066 to support useful loads in all directions. This load may be a combination of the arm weight and acceleration forces and payload in any direction. The use of the magnetic forces to provide the bearing seating force and axial preload on the bearings allows for the use of thrust load and/or angular contact bearings which can be preloaded by the magnetic attraction of the stator and rotor to remove bearing play in the axial direction. By using a combination of bearings that are radially and axially locating, it is possible to preload the bearings with magnetic force, in radial and axial directions and to eliminate the need for additional mechanical retention of bearing races 1088 to prevent movement of the races in the opposite direction of the magnetic force. This preload eliminates bearing play and increases bearing rigidity such that the assembly becomes very precise in its movement. This has advantages for precision applications such as robotics. It also has the advantage of reducing the inconsistent cogging effect that could result from radial displacement of the rotor. This is especially important when the device has a high number of very small cogging steps such as with embodiments of the device.

[0152] Windings 1090 in actuator 1062 may be of any suitable design. A number of stator posts 1080 and rotor poles (magnets) 1082 may be used to provide a desired number of cogging steps. For example, if there are 1096 stator posts 1080 and 1092 rotor poles 1082, then over 2000 cogging steps may be provided (least common multiple of 1096 and 1092. In addition, it is desirable to evenly distribute load on the bearings 1076, 1078 and this can be provided by having four or more regions of peak magnetic attraction, such as is provided by using 1096 stator posts 2410 and 1092 rotor poles 2310. The number of regions of peak magnetic attraction is the greatest common divisor of 1096 and 1092, namely four in this instance.

[0153] A non-limiting example of axially preloaded races with no need for mechanical retention of the races 1088 on the bearings 1076, 1078 is shown in Fig. 28 where the inner roller bearing 7108 (in this non-limiting example, a cross roller bearing) is sandwiched between two bearing grooves such that the axial magnetic attraction between the stator 1072 and rotor 1074 eliminates axial and radial play in the bearing 1078. The bearing 1078 is, in this non-limiting exemplary embodiment, a cross roller bearing with axial and radial locating stiffness. As a result, the axial preloading of the rotor and stator provided by the magnets 1082 in the rotor 1074 results in a precise relative location of the stator 1072 and rotor 1074 in the axial and radial directions. This precise location is accomplished without the need for mechanical or adhesive bearing race retention in the opposite axial direction of the magnetic attraction force between the stator and rotor. A counterbearing 1091 may be used to prevent unwanted separation of the rotor 1074 and stator 1072 under load. The counterbearing 1091 is fixed to one of the stator and rotor and overlaps a part of one of the other and the overlap may form a bearing for example with use of bushings at the contact between moving parts.

[0154] Examples of control motions:

[0155] These movements are described relative to Fig. 23, Fig. 24 and Fig. 29. Fig.

29 shows a detail of an example of the arm control 1022 of Fig. 24. The operator's arm 1092 rests in curved arm rests 1094. The arm rests 1094 are attached to a lever 1096 that attaches to the robot arm between the wrist Wl and the wrist W2 at the gimbal 1098. Movement of the arm 1092 and consequently the elbow of the arm 1092 up or down causes a rotation about the gimbal 1098 around a horizontal axis (motor cycle throttle) and movement of the arm 1092 sideways (left or right relative to the user) causes a rotation of the lever 1097 relative to the gimbal 1098 about a vertical x axis. A compensatory rotation of the lever 1097 relative to the lever 1096 about pivot or gimbal 1099 also occurs. Control signals are sent from the gimbal 1098 to the controller 1024 of Fig. 23 to drive corresponding actuators. For example, move the arm 1092 to right, the actuator A4 goes counterclockwise (cc), the actuator Al rotates clockwise (cw). The hand control 1020 need not move during the movement since the operation can compensate with movement of the operator's wrist. Thus if the operator moves the arm 1092 side to side, this causes a movement clockwise about the gimbal 1098, the actuator A4 moves counterclockwise under angle to speed control, with actuator Al moving clockwise, actuator A2 moving counterclockwise, and actuator A3 moving clockwise, in proportion as provided by a lookup table in the controller 24. The actuators move so that the hand control 1020 does not move. The overall effect is that the robot arm follows what the arm 1092 is doing. So a movement of the elbow arm to the right causes the Scara to rotate to the right and draw the forearm of the robot arm around to the right. To do this motion, the controller 1024 needs to do some computation. The controller 1024 needs to know angle of the actuator A4 relative to a radius from the base Bl of the Scara, and likewise needs knowledge of all arms and the angle information may be provided by an encoder or by storing the stepper motor control signals. The end result is approximate alignment of hand input with upper arm plane at all times. Movement of human elbow 1092 up and down rotates a forearm gimbal 1099 on horizontal axis, the elbow El extends, makes the forearm between Wl and El go horizontal or tilt, the shoulder SI extends, the Scara retracts, the elbow El goes down, and actuators A1-A2-A3-A4 rotate so that the Scara retracts.

[0156] If one of the controls such as the forearm control of Fig. 29 provides signals to drive an actuator through the controller 1024 that is also provided signals by another control such as a hand control 1020, the controller 1024 sums the control signals. The same applies when a single control such as the hand control 1020 provides two different control signals to the same actuator. Thus, a translation sideways (normal y axis control) of hand control 1020 can causes different commands, as for example x axis control. Thus, for example, if the hand is moved at 45° to the forward direction, this can cause equal x, y axis movement. The control inputs add or subtract, and need not be very precise due to reaction input from the hand control 1020 and forearm.

[0157] As shown in Fig. 30A, Scara base 1112 may be fixed to a surface by vacuum suction or any suitable fastener arrangement, and may comprise links L101, LI 02 and LI 03 connected by actuators A101, A102, A103 and A104. The robot arm 1110 may be designed as shown in Fig. 23, and the base of the shoulder SI may be oriented at an angle to vertical, for example tilting backward (towards the right in the figure) 10 degrees to 30 degrees. The first link L101 may comprise a base B101 for securing the Scara base 1112 to the surface of an object and a bearing element 1106 for rolling or sliding on the surface. The bearing element 1106 may comprise a low friction surface or rolling element such as a ball bearing.

[0158] All actuators disclosed in this document may be axial flux motors having the hollow design shown in Fig. 27 or Fig. 28, although other actuators for example disclosed in WIPO publication WO2017024409 published February 16, 2017, may be used. Wires and other components for sending power and control signals, or cooling fluid, if present, may pass through the hollow actuators. Each axial flux motor comprises a stator and rotor. The order of the stator and rotor in any implementation of a motor or actuator is not relevant. In a design of the actuator, the selection of the height of the posts, number of posts and pole density may follow the description in WIPO publication WO2017024409 published

February 16, 2017. There may be many short posts and many poles. The number of poles and posts may be determined based on the size and torque requirements of the intended application.

[0159] Fig. 30 A and Fig. 30B show two embodiments of a Scara. In Fig. 30A, each link L102, L103 of the Scara rests above a previous link, so that the links are stacked in the axial direction of the actuators. In Fig. 30B, the first link LI and third link L3 underlie the second link L2 of the Scara. Various Scara designs may be used.

[0160] The signals from the hand control 1020 received by the controller 1024 may be translation control signals or rotation control signals. Everything upstream of the hand control 1020 may be position to speed control. All the downstream actuators may be controlled by angle control. An upstream actuator may be controlled in unison with a rotation of the end effector 1016. An x - y displacement may causes radially outward movement away from selected point. If shoulder SI, elbow El and wrist Wl are present, then a vertical displacement of the hand control 1020 causes elbow speed rotation to move hand control 1020 in arc outward along a radius, and rotation of shoulder SI causes upper arm (between shoulder S I and elbow El) to move upward. Movements may be scaled so that a vertical displacement of the hand control, for example 1 mm, may cause elbow to move 10% up and radially outward. Use of a hand control 1020 and the control system allows reactive movements by the operator to compensate for movements of the robot arm. This happens because the hand control 1020 resists movement as the arm translates, so that the operator pulls back on hand control 1020. The operator can always be adjusting to the movement of the arm as carried through to where the hand control is on the arm. [0161] The controller 1024 may be made up of one or more controllers. A single device is shown for convenience. The number of steps that cause a given amount of speed or rotation angle may be varied. For example, if an elbow El is present, a vertical displacement of the hand control 1020 increases elbow angle. The hand control 1020 then moves forward on an arc created by movement of the arm at the elbow El, creating a relative displacement towards the base and the Scara and shoulder SI retract to result in generally vertical motion of the hand control 1020. For another example, if there is a shoulder SI and no actuated elbow El, then vertical translation of the hand control 1020 results in a rotational speed command to shoulder S 1 , and a horizontal translation does not cause shoulder to rotate. Additional controls may be provided for damping, acceleration rate and deceleration rate, speed control and safety stops. A separate control such as a dial under a hand control may provide signals to control the actuator A4, or otherwise rotate a shoulder S 1.

[0162] A vertical axis actuator at the wrist may be operated independently of other actuators in the wrist. This actuator may work with shoulder rotation by actuator A4 or start with a delay and be proportional, both could be user set. The end effector 1016 may be operated in plane with the robot arm, and particularly in plane with the wrist Wl and elbow El. Depending on the amount of payload, there may be some out of plane bending. A current sensor at the corresponding driver may be used, or a multidimensional load cell between end effector 1016 and wrist Wl. Feedback from the current sensor or load cell may be compared with a threshold or standard based on known energy consumption for the actuators when loaded off plane and the length of time the end effector 1016 is off plane may be limited. The higher the load, the lower the out of plane angle permitted for a given time. For a shorter time of off plane load, a higher off plane load may be permitted.

[0163] The actuator A4 may be also operated in angle to angle mode. If there is an actuated elbow El, the shoulder SI may rotate about a vertical axis proportionally to Scara axes to accommodate rotation of the last Scara link. The shoulder S I, when the Scara is actuated, may translate approximately along a radius. All first five of the actuators Al through A5 may rotate together. However, if no elbow is present, then the shoulder S 1 may be actuated independently to the Scara actuators. As actuators of the shoulder SI rotate, this changes z height of the end effector 1016. If shoulder SI, elbow El and wrist Wl and/or W2 are present then a vertical displacement causes elbow speed rotation to move hand control 1020 in arc outward along a radius, and shoulder S I rotation causes upper arm to move upward. This displaces hand control 1020 upward and/or forward and natural action is for operator to counter resistance provided by springs on hand control 1020 so that operator pulls back on hand control.

[0164] As shown in Fig. 31A and Fig. 3 IB, there may be manually actuated joints

1120, 1122 before and after the actuator stacks at the shoulder, elbow or wrist of a robot arm 1010. In proportional rotation, subsequent actuators in a stack match a predetermined angle to the first actuator, for example three Scara actuators and one shoulder actuator may match the rotation angle of a first Scara actuator. To control the angle, each of the actuators for example the first four actuators are different sizes with different pole counts or different step counts. Whatever step per second is required of first actuator Al, then send same number of steps to other actuators A2-A5 in series. Different sizes or pole counts of the actuators A2- A5 will then effect a different amount of rotation or rotation speed. In instead, different step numbers are used, different motor controllers are needed. The operator can walk with hand control 1020 forward and adjust to how much arm extending.

[0165] The following operational control layers may be present.

[0166] Layer CI is the proportional angular rotation of the Scara actuators A1-A4.

Layer C2a is the operator can adjust for non-linearity of motion at end of Scara arm, so that if the robot lags behind, the operator pushes more. Layer C2b is that the speed response changes depending on the angle of the first actuator, for example actuator Al in the Scara. As the robot arm is extended, the same displacement of the hand control 1020 results in greater rotation speed of actuators. The feedback loop is human operated and learnable. Layer C3 is side to side translation when operator moves hand control 1020 right or left. Displacement distance controls the speed of either just the base actuator Al or four Scara vertical axis actuators. Operation of this layer may use a look up table in the controller 1024 to condition the signals to the drivers. For example, for a fully extended Scara, actuator Al might rotate 20°, actuator A2 might rotate negative 30° actuator A3 might rotate 40°, and actuator A4 programmed up to some number of degrees depending on the amount the hand control 1020 is pushed left or right. This process may use preprogrammed proportionality, with the proportion values stored in a lookup table in the controller 1024. For layers CI through C3, the hand control may be remote.

[0167] In layer C4, a vertical motion, the operator lifts the hand control 1020 straight up, elbow El extends by use of multiple wedge actuators rotating oppositely or by use of an actuator with a horizontal axis. As the elbow El extends, the hand control naturally is pulled backward, which causes Scara arm to retract slightly. The hand control 1020 may be rigidly fixed to the robot arm or attached through a spring. The controller 1024 may need to know what angle the hand control is at relative to the robot arm to identify what vertical motion is possible, for example by using a sensor. In layer C5, the wrist Wl is controlled by angular displacement or rotation about its own axis of the hand control 1020. A movement of the hand control 1020 (for example, without a spring) may cause a proportional angular displacement of end effector 1016. The end effector 1016 may point straight out, then if the hand control 1020 rotates left, the end effector goes left, same amount at same speed, using for example a stepper motor forming an actuator that is the closest actuator to the end effector of the stack of actuators forming the wrist Wl. The angle movement of the hand control 1020 may be proportional to angle movement of wrist Wl and could be adjustable so N degrees of rotation of hand control 1020 corresponds to KN degrees of movement of end effector 1016. K is a factor that could be preset or adjusted on the fly. K may be stored in the controller 1024.

[0168] Layer C6 is an override. An override might occur due to a sudden change in direction, angle rotation or speed of the hand control or forearm control, or sudden change of payload displacement, angle rotation or speed. If an override condition occurs, an interrupt may be sent by the controller to stop all signals from the drivers reaching the actuators. In addition, if the operation lets go of hand control, the system may go to interrupt. If vibration of the load is too high, this may be detected by a load sensor on the end effector 1016 and all actuators stopped until vibration goes below a preset level. [0169] In Layer C7, the proportion of hand control 1020 rotation to wrist rotation may be preset or set by operator button. For example, rotate hand control 45°, wrist rotates say 22.5°, and actuator A4 also rotates 22.5°. The controller 1024 may do some

computations to rotate A 1 , A2 and A3 to avoid translation at wrist, which can be done by standard reverse kinematics.

[0170] The shoulder SI may be a horizontal axis actuator or stack of rotary wedges, and operated as with each of the disclosed stacks. The shoulder SI causes a vertical motion of the robot arm. At end positions of the shoulder S 1 , more rotation steps of the actuators in the stack are needed to achieve a given vertical motion as when the shoulder is at a 90° position. At an initial position, the shoulder SI is fully retracted, all of the actuators at 180°, with thin end of each wedge pointing back towards the base of the Scara 1012. When all actuators are at zero degrees 0°, all thin edges are in the opposite direction, fully extended. At 90°, the shoulder S 1 is half extended. So long as each actuator rotates equal amounts in opposite directions, the arm never goes off plane. For force multiplication arrangement due to the angle of the actuator axis relative to an adjacent actuator, the actuators may be thin, for example sixteen millimetres (16mm). If actuators rotate differently, the arm goes off axis. This is good for dexterity, but loses mechanical advantage of the wedges in the joints.

[0171] In layer C9, the wrist Wl is provided along with a second wrist. This allows rotation of the end effector 1016 by rotating only a vertical axis actuator. The wrist Wl can be used to keep the wedges of a second wrist in plane to avoid excessive power

consumption. To keep an actuator vertical, a computer computation might be needed based on the number of steps rotated by each actuator for a given position. This computation is sufficient to keep the actuator vertical. An additional set of forearm actuators may be provided to fix the robot arm. Fixable actuators 1120, 1122 like those shown in Fig. 31 A and 3 IB may be rotated on a bearing, set with a brake and locked in preferred position. Manual actuators may be user adjustable, and may be used for example to rotate the robot arm off axis so the wrist remains on axis. Manual actuators may be used anywhere in the robot arm. In Fig. 31 A and 3 IB, the manual actuators 1120, 1122 are located at the upper part of the wrist W 1 or the bottom of the shoulder S 1 closest to the Scara. A manual actuator may also be provided at the wrist W2 before the end effector 1016. The end effector may also be replaced by a quick detach bracket, which may be located at the end of a series of fixed joints between the bracket and wrist W2.

[0172] The elbow El and shoulder SI can operate with any joints, not just wedges, in some embodiments.

[0173] If it is desired to keep the wrist array formed of Wl in plane, for maximum lift, twisting the hand control 1020 from side to side may rotate the shoulder (which is behind the operator) in rotation angle to proportional rotation angle mode. This maintains the ideal in-plane alignment of the shoulder, elbow and wrist. The upstream Scara joints can, optionally but preferably be commanded to counter rotate so the additional input from the hand control are minimized. Optionally, because there is some ability to go out of plane with the joints, the wrist could bend to the side slightly when the hand control is rotated about a vertical axis with the shoulder rotating in unison. In some applications, a servo mode may be provided.

[0174] A force transducer may be provided at the end effector 1016. When an operator is about to move a payload, the operator may stop all motion and zero the force transducer. If the sensor feels contact of the end effector with a body, the controller 1024 may be configured to change the sensitivity of the relationship of the amount of translation to the speed of the actuators. For example, if in an initial state 1 mm corresponds to X speed, the sensitivity may be changed to 5 mm to X speed. This modification of sensitivity may be applied to all drivers and actuators, and all drivers and actuators may be shut down if the sensor feels contact above a given limit.

[0175] Fixed wedges 1120, 1122 in Fig. 31A and 3 IB may be used above and below the wrist and the shoulder. The advantage of such wedges is to lower power consumption, especially with a high payload. For increased payload, wedges may be adjusted so that repetitive operation with high load is done primarily near rotational limit of shoulder, wrist or elbow, with the actuators at near 0° or 180° to provide the greatest mechanical advantage. Manual wedges 1120, 1122 may also be used to change side to side angle of the bottom actuator and the top actuator of any joint, which aids in increasing dexterity and clearance between the robot arm and the operator. There may be multiple dials or manually operated wedges, each one rotating the vertical axis of shoulder S 1 separately. The manual operation of one of the shoulder joint manually operated wedges may be opposite to the rotation of the Scara 1012.

[0176] A wrist motion of the operator about the x axis, which corresponds to twisting about the axis of the forearm may rotate the last actuator in wrist array W2. The load cell could be before or after the last actuator. Angle to angle operation for the actuators for the wrist W2 may be limited to operator limit of motion, with a change in mode of operation of the robot in a given range of movement. If the operator is in a space with a 90° limit on any axis, for example with objects near the operator, then the controller 24 may be configured so that when the wrist has rotated a given amount, for example 80°, a further change in angle of the hand control 1020 causes a speed response in the actuators. The region in which the change in mode of control occurs may be set by the operator, for example from 10° to 20°. In a stowing mode of operation, the operator may move the hand control to make the end effector 1016 to move in a direction, then if the operator releases the hand control, the controller may be provided with a signal from the hand control indicating the release of the hand and then send a signal to slow all actuators.

[0177] An exemplary design of the wedge joints that may be used for any of the joints SI, El, Wl or W2 is shown in Figs. 32A, 32B 32C and 32D. The more wedges, the lower wedge angle and more mechanical advantage. Mechanical advantage results from ten actuators rotating 180° with resulting output of only 90° or 45°. The torque on individual actuators may be kept relatively low. For example, if the robot is lifting 150 lbs, the torque on each actuator may be one half of passive cooling power.

[0178] In general, the operator may apply translational or rotation force that controls movement of entire robot. Rotational forces or movements control or primarily control wrist. Translational forces, up, down, side to side, may control movement of actuators from the base of the Scara to wrist. The actuators may be very quick acting. Sensitivity of the hand control may be set by the operator. In a safety mode, motion controller 1024 may have a programmed instruction that at any time the robot arm at the end effector 1016 or at hand control position receives a reverse motion command, the robot will stop momentarily (pause) at zero speed position. This prevents an instantaneous reverse. The length of pause at the stop may be controlled. When there is reverse motion, the motion controller 1024 may stop all motion, or stop motion in the current movement direction, or stop movement in the opposite direction. As an alternative to a set pause, the controller 1024 may stop all motion until the operator moves the hand control back to a neutral position, at a position where the hand control is not generating any commands to the controller.

[0179] If there is a spring in the hand control that biases the hand control to a neutral position in both translational and rotational directions, the operator can tell from the forces about where the neutral position is. The operator may also release the hand control when there are springs in the hand control so that the hand control moves automatically to neutral position. In another failsafe mode of operation, if sensors on the robot arm detect an excessive force, speed change or rapid change in direction, the controller 1024 may be configured to stop all actuators. In operation, the operator gains skill in moving the control arm learns to avoid unintentional movement. If the operator accelerates the arm and payload, and decelerates so that the end effector 1016 reverses direction, the controller 1024 may be configured to send a command to stop all motion and the operator must let go of hand control. When the hand control returns to neutral position via springs and robot has stopped moving or has reached low enough level of oscillation, an indicator light or audible signal allows the operator to hold on to the hand control. In general, when approaching a specific position, for example a neutral position, the controller 1024 and the operator should slow movements to avoid overshoot.

[0180] Control wires and power wires may go through the middle of the robot arms.

For cooling, air may be drawn through the hollow centres of the arms and may be released to atmosphere through the base. The air may be blown with a pressurized air system or drawn through with vacuum located anywhere on robot. Base may be secured to surface by vacuum for simplicity with a pump on top of the Scara. The Scara needs to be relatively stiff in torsion because the robot lifting arm might be at 90° to the Scara. There may be any number of arms on the Scara. The base of the robot lifting arm may be angled away from structure (Fig. 30A), which allows a different range of motion than if horizontal.

[0181] The actuator control may be a servo feedback control or closed loop, or stepper motor with open loop control. A closed loop needs feedback with an encoder, which is more expensive and complex but results in more precise control and higher efficiency. Side to side motion is controlled by Scara arm actuators A1-A4, which are typically larger than the shoulder SI, elbow El or wrist Wl actuators. Larger actuators allow higher step count, so more than the combination 96 poles with 92 posts. The stepper motor steps are not necessarily discrete, but may use microsteps as known in conventional stepper motors. The current control for step to step may be proportional to the movement of the hand control.

[0182] The system may be mass and inertia compensated so the operator feels the weight or inertia of a load. The system does scale motions of the operator to the load. The spring force on the hand control, if present, may be varied by haptic feedback to the controller 1024. If the payload is being connected to something, the controller 1024 may sense contact and send signal to the hand control. If the hand control is located at or near the wrist, it is expected that mechanical vibration of the payload will be experienced by the operator. It may be beneficial for the operator to have their forearm rest on the robot on the arm rest of Fig. 39 for example. The arm rest may be rigidly fixed to the robot arm or rotationally fixed with or without a spring and damper. Thus, the operator only needs to control wrist and not arm. The forearm rest may be configured to allow the arm to be easily removed from the rest, for safety and comfort, for example using upwardly open curved or cup shaped rests 1094. There may be vibration sensor at or near the end effector 1016 that sends feedback to the hand control or give audible signal to ear bud, which may be useful in noisy environments. While it is important to avoid damage to surroundings, for example by the auto stop feature, that excitation prevention strategy may be applied only above certain speed.

[0183] A base actuator of any one of the sets of actuators may have vertical orientation, or parallel to main force being acted against. For rotation about the y axis, in a simplified control mode of operation, the array of wedges in a wrist W2 may start with a vertical axis, downstream of the hand control. The first actuator 1030 may be the only actuator responsive to a rotation about the y axis of the hand control. In this case, the actuator stack of wrist W2 stays in plane and rotates, every second actuator in one direction, every first actuator except the actuator 1030 oppositely, which causes a near rotation about the y axis, and at the same time the end effector 1016 lifts, which results in a need to change the elbow El or the shoulder SI. The operator does this naturally by moving hand forward and change height a bit, which adjusts the shoulder and the elbow. The manner of control about the y axis may be operator selected, for example by (1) rotation of base actuator Al only (eg when operator paints in cylinder) (2) base actuator Al rotates in one direction, base actuator A4 of shoulder rotates in opposite direction or (3) base actuator Al rotates one direction and shoulder actuator A4 in same rotation. These controls may be speed control, with a pre-set response of each actuator in relation to a preceding actuator, so that all actuators rotation in proportion to each other in master-slave relation. The proportion could be programmed with a simple algorithm, or the controller 1024 could be set to modify the proportion based on the position of the robot arm.

[0184] For example, with a vertical lift of the hand control: the elbow El extends, the wrist Wl rotates in proportion to the elbow so that the vertical actuator stays vertical, the user naturally moves hand control (reaction translation of hand control) in a way that the shoulder SI moves because the Scara moves, which changes the angle of the elbow El. There is an ideal rotation of the wrist Wl to keep the vertical axis actuator vertical. The actuator need not be perfectly vertical, so in some cases there may be no need to move shoulder S 1. If the shoulder S 1 horizontal axis actuator stack or equivalent horizontal axis actuator is not present, the elbow El and the wrist Wl may be necessary, depending on the application. In some embodiments, the vertical lift function of shoulder S 1 may not be needed.

[0185] The end effector 1016 grip and ungrip functions may be controlled by a trigger on the hand control for example using a driver 1028. If the rotary wedges of a joint introduce an unintended side to side motion of the end effector 1016 if they are not rotating perfectly in unison, a closed loop feedback may be needed in the rotary wedge joints. Another embodiment could use one or more wedge sets that could be closed loop which could be used on their own for very fine movements. When stepper motor control is used, individual sets of two or three wedges could be added or subtracted from the array or stack of wedges, such that the finer the movement required, the more sets that would be activated.

[0186] In an embodiment, a change in hand control angle results in a proportional change in angle of the end of the wrist. If a predetermined hand control angle is exceeded in a direction (different directions can have different limits which correspond to the limits of the range of angular motion of the human operator) the end of the wrist may change from an angular displacement mode to an angular speed mode past a predetermined limit. The hand control may rotate at the same speed and angle as the end of the wrist Wl so the hand control will be aligned in the neutral position of the robot wrist when the speed rotation command is over and the hand control is returned by the operator to the neutral position.

[0187] If three sets of wedges are used, the array would be able to rotate in any direction at any time. The neutral position would be with each set at 120° to each other. Then one or more actuator sets can be rotated to bend the whole assembly in any direction. If the wedges are greater angle than necessary for the desired assembly range of motion, the wedges can be used at less than 180° rotation. The wedges may be controlled to have hard stops or possibly sprung stops between wedges for various effects such as using spring force to reduce the actuator torque when supporting off -plane motions with a payload.

[0188] In any one of the actuators, a certain level of friction may be advantageous for the stepper motor control because it prevents the actuators from jumping from step to step. With no friction, there is only inertia to prevent the actuator from jumping from one discrete step to the next. With a certain amount of non-stick-slip friction (such as is common to a preloaded roller bearing, or a Teflon™-on-Teflon™ sliding contact) there is a certain level of current that is required to overcome this friction. Embodiments of the actuator use magnetically preloaded bearings which may provide the necessary non-stick friction to the actuator providing a smoother transition from step to step.

[0189] In another embodiment, shown in Fig. 28, bearings 1076 and 1078 may be used in combination with a low friction surface combination between the stator 1072 and rotor 1074 such as, but not restricted to, in the airgap. Teflon™ on Teflon™, for example, as very low stick-slip-friction and would allow smooth operation of the actuator in stepper mode by requiring a high level of torque from the actuator to overcome this friction. A material like Teflon™ has a unique characteristic which allows micro movements to be achieved through a variation of force on the movable structure which is rotationally or otherwise movably attached to the fixed member.

[0190] In the robot arm with the elbow joint El and the shoulder joint SI, both joints may respond to a vertical translation of the hand control 1020. In a more simple operational mode, only the elbow El responds to a vertical translation. The shoulder SI may also respond to a vertical translation but it is a secondary or reaction effect where the horizontal component of the vertical movement that results from the arc movement of the forearm around the elbow axis moves the hand control bracket radially away from the operator and as a result of the operator resisting the movement of the hand control radially, a horizontal (and radial) displacement of the hand control occurs relative to the arm. This relative horizontal movement of the hand control has a pre-set response.

[0191] In other words, the vertical displacement for the hand control results in an extension of the elbow El only. The extension of the elbow El may result in a horizontal movement of the hand control connection to the robot arm (hand control base). When the hand control base moves horizontally with the robot arm, it results in a displacement of the hand control relative to the hand control base. This secondary effect may send a retract command to a different set of actuators that retracts, for example, the Scara and/or shoulder SI.

[0192] Or, in other words, the elbow joint El may respond vertical displacement of the hand control by extending until it corrects the error. That is, the extension of the elbow El acts to bring the hand control back to zero displacement in the vertical direction. The horizontal movement of the robot arm at the hand base (relative to the operator) creates a secondary error in the horizontal direction which results in a retract command to one or more actuators that respond according to a predetermined relationship to correct the horizontal error. Other tertiary, quaternary etc. errors may result in other directions, but with all of the possible translational planes linked to one or more actuated joints, the various sets of actuators will move in unison but independently of each other to approximate the trajectory of the hand control. It is understood that the arm, in this example, will be displaced initially in an unwanted direction before the horizontal error registers at the hand control 1020 and in the controller 1024, but it is believed that the operator will learn to compensate for this imperfect motion path and may even learn to anticipate it to prevent it from happening at all.

[0193] The cogging steps of an actuator are not necessarily the same as the powered steps that result from the commutation of the electromagnets.

[0194] Fig. 32 A shows a stack of exemplary wedges 1142 in a wedge stack, here with three actuators and four wedges 1142. Each actuator comprises a stator 1144 and rotor 1146, which each can be made according to the designs disclosed in this patent document, preferably axial flux hollow interior actuators held together with magnetic forces using preloaded bearings 1148 (only the races are shown, ball bearings are not shown) and with a locking or safety ring 1150 on an outside or inside perimeter of the actuators. Fig. 32B shows a detail of Fig. 32A with the stator 1144, showing coils, and rotor 1146 that has magnets.

[0195] Fig. 33A shows a section through two adjacent wedges 1142 held together also by a safety ring 1150, and having an actuator formed by stator 1144 and rotor 1146 combined. A stator and rotor combination on each opposing face will therefore be at an angle corresponding to the angle of the wedge. Each opposing face defines a plane that the stator-rotor combination rotates in. Rotor 1146 has posts that hold magnets in the rotor and a unitary backiron. Stator 1144 has coils around posts and a unitary back iron.

[0196] Fig. 33B is an exploded view of two wedge housings 1143, showing an actuator 1145 formed of stator 1144 and rotor 1146, and safety ring 1150. Each housing 1143 may be a unitary element. The angle of the wedge housing 1143 can be seen in Figs. 33A and 33B.

[0197] Referring to Fig. 34, there is shown a robot system 1160 comprising a slave robot arm 1162 and a master robot arm 1164. The slave robot arm 1162 comprises actuators, including at least a first actuator 1168 that rotates in a first plane, a second actuator 1170 that rotates in a second plane and a third actuator 1172 that rotates in a third plane. Each plane is perpendicular to the plane of the figure and the line in the figure that represents each actuator lies within the plane corresponding to the actuator. As illustrated in Fig. 35, for the case of actuators 1168 and 1170, the first plane is at a first angle Al between zero and 90 degrees from the second plane. Likewise, the second plane is at a second angle A2 between zero and 90 degrees from the third plane.

[0198] The master robot arm 1164 comprises actuators, including at least a fourth actuator 1174 that rotates in a fourth plane, a fifth actuator 1176 that rotates in a fifth plane and a sixth actuator 1178 that rotates in a sixth plane. Each plane is perpendicular to the plane of the figure and the line in the figure that represents each actuator lies within the plane corresponding to the actuator. As illustrated in Fig. 35, for the case of actuators 1168 and 1170, the fourth plane is at a third angle A3 between zero and 90 degrees from the fifth plane and the fifth plane is at a fourth angle A4 between zero and 90 degrees from the sixth plane.

[0199] Each actuator may be made in accordance with the actuator described herein, or as described in US published patent application US20170338705 or as described in US20170187254, both of which are incorporated herein by reference where permitted by law.

[0200] Each of the actuators 1168, 1170 and 1172 may be comprised of a respective stator and rotor pair, and each stator and rotor pair is provided with sufficient friction between the stator and rotor that the stator and rotor do not move relative to each other under normal operational loads without being energized. The friction between each stator and rotor pair may be provided for example by loaded bearings or sliding bushing surfaces, for example by friction between the counter-bearing 1091 and the rotor 1074. The friction between stators and rotors of the master robot arm need not be so limited.

[0201] A robot controller 1166 is responsive to positioning of one of the actuators

1174, 1176 and 1178 to control the position of at least the actuators 1174, 1176 and 1178. Lines connecting the robot controller 1166 to the slave robot arm 1162 and master robot arm 1164 depict unidirectional or bidirectional communication channels that may be any conventional communication channel including wireless, optical and wired. The actuators may include encoders, not shown, that provide signals to the robot controller that are indicative of position of the actuators. The robot controller includes a memory,

microprocessor, drivers for the actuators and interfaces for the encoders, as well as a user interface. These elements are conventional in robot controllers and are not separately described.

[0202] In one mode of operation, the robot controller 1166 is responsive to positioning of the actuator 1176. In this mode of operation, the actuator 1176 is not driven by the robot controller 1166, but is responsive to movement of the robot arm 1164 for example by an operator, who may be a surgeon, manipulating an end effector 1182 at the end of the robot arm 1164. The end effector 1182 may include a surgical instrument. As the end effector 1182 moves, the actuators 1174, 11764 and 1178 begin to move relative to each other. The robot controller 1166 responds to positioning, in this example, of the second actuator 1176 to drive the actuators 1174 and 1178. In addition, the robot controller 1166 drives the actuators 1168, 1170 and 1172 in a corresponding manner. In one mode of operation, the corresponding manner is to effect scaling of the movement of an end effector 180 with the movement of the end effector 1182. Thus, for example, if the end effector 1182 is moved through a given amount, then the end effector 1180 may be driven a fraction of the given amount. The operator therefore may use a coarser movement at end effector 1182 to cause a finer movement at end effector 1180. This scaling effect may smooth out non- linearities in the control system.

[0203] The scaling function may be provided by selecting the angles between the planes of the actuators of the master robot arm to be a fraction of the angles of the planes of the actuators of the slave robot arm. Thus, A3 may equal Rl x Al, where Rl is a fraction between 0 and 1, and A4 may equal R2 x A2, where R2 is a fraction between 0 and 1. Rl may equal 1/Nl for some natural number Nl, for example Nl = 10, and R2 may equal 1/N2 for some natural number N2, for example N2 = 10. In an example, A1=A2, A3=A4 and Nl = N2. In a further example, A1=A2=30 degrees, and A3=A4=3 degrees, which effects a 10: 1 scaling of the slave robot arm 1162 to the master robot arm 164.

[0204] Each actuator may comprise a hollow, axial flux actuator, and drive signals from the robot controller 1166 may be provided to the actuators 1168, 1170 and 1172. [0205] The robot controller may be configured to drive the actuators oppositely alternately.

[0206] The angle of an actuator relative to an adjacent actuator may be referred to as a wedge angle. The arms between actuators effectively form wedges. An actuator may have a wedge angle as low as 1 degree or lower. Bearing friction in each slave actuator may be set to make the slave actuators non-backdrivable in the load bearing direction in any position of the wedges. The friction should be non-stick-slip friction. Commutation of the electromagnets in the actuators with smooth current profiling allows a smooth ramp up force against friction.

[0207] The friction in the actuator may arise for example from ball bearing friction resulting from axial magnetic forces on the bearings. For this purpose, a radially rigid roller bearing preloaded in axial and radial direction by magnetic force may be used. The friction may also be created by sliding contact or bushing for outer bearing or could be sliding contact between stator and rotor posts, or an embodiment may have layer of Teflon™ or the like coating on the rotor and stator, for example there may be carbon coating, or other smooth surface bearing against smooth surface. A material such as Teflon™ that has lower static friction than dynamic friction may be used for the rotor to stator smooth surface contact. Another possibility for a contact material between rotor and stator is spinodal bronze, though it is less ideal for medical purposes because it is red. An opposed surface becomes coated with nickel that migrates out of bronze coating. An example of an actuator with a sliding contact bearing surface is shown in Fig. 36. Carriers 1190 and 1192, one of which is a stator and the other a rotor, have electromagnetic elements 1194 and 1196 respectively mounted opposed to each other for electromagnetically driving the rotor with respect to the stator. At least one of the sets of electromagnetic elements 1194 and 1196 is commutated electrically. The drawing is not to scale. In practice, air gap 1198 can be very small. The drawing is a section through one side only of a hollow annular axial flux electric machine. Sliding bearing surfaces 1200, 1202, 1204 and 1206 as discussed here may contact each other and provide friction for the actuators in the slave robot arm 1162. [0208] In the determination of bearing friction, the designer calculates the maximum payload, and designs the actuators so that friction coefficient and axial preload result in higher resistance than torque resulting from the maximum payload. The friction requirement may be reduced by using a rotating wedge configuration. Thus, for example, a 1 degree angle wedge requires very low friction force to ensure rigidity when power is lost. The angle of the wedges may be matched to the coefficient of friction and axial force on actuators.

[0209] Although a design is shown in Fig. 34 with a shoulder 1184 resting on a support 1186, for example a table, there may also be an elbow or wrist as shown in other embodiments of a robot arm disclosed herein.

[0210] The wedge sets may have more than two wedges, and therefore more than three actuators. The wedges in a stack rotate oppositely so that if the first wedge of a pair rotates clockwise, the second wedge of the pair rotates counter clockwise. If the master robot arm 1164 has N wedges then each odd wedge may rotate clockwise and each even wedge may rotate counter clockwise. The even wedges may rotate the same amount as each other and the odd wedges may rotate the same amount as each other. An amount is an angle. In the master robot arm, only one actuator need not be driven, the other actuators in the master robot arm may be slaved to the one actuator. The operator moves just the end effector and does not need to know which actuator is not slaved. The operator may also be provided with a switch to disable one or more actuators and move only a specific actuator. For example, the operator may disable actuators 1174 and 1176 and rotate only actuator 1178. The signal from the actuator 1178 may then be used to drive the corresponding actuator 1172. In this instance, if the actuators 1168 and 1174 are parallel to the support 1186 and the support is horizontal, this motion corresponds to a rotation about a vertical axis of each entire robot arm. The actuators in a wedge stack may all rotate in unison.

[0211] Motion of the actuators 1168-1178 may be impeded when all actuators are aligned with the thinnest part of the wedges all in the same plane as the load (wedges at top dead centre, which corresponds to a rotational position of zero or 180 degrees, that is, two different positions). Therefore, the actuators 1168-1178 may be restricted from being at rest at top dead centre by a physical stop or software stop, for example at about 5 degrees from top dead centre. The actuators in a stack of actuators for example actuators 1168-1178 and the corresponding wedges may rotate up to about 180 degrees, but may be restricted to travel of about 160 degrees or 170 degrees, for example from 5 degrees off top dead centre to about 175 degrees off top dead centre. With restricted angular motion, wires to carry power and drive commands, as well as sensor or encode signals, may be provided from one actuator to another through the hollow interior of the robot arms.

[0212] A force sensor or transducer (not shown) may be provided at the end effector of the master robot arm 1164 to detect the payload force, and send a signal back to the robot controller 1166. The robot controller 1166 may be configured to sense the force sensor signal and drive the actuators 1174-1178 to provide a controlled feedback or haptic force to the operator. The force transducer sends a signal to the robot controller, which determines which slave actuators need to be energized to reproduce the payload force.

[0213] According to this system, an angular motion of X degrees by the operator may correspond to an angular motion of X/R degrees where R may be a natural number, for example 10 where the wedge angle of the slave is 10 times the wedge angle on the master. Another possibility is to use stepper motors for the actuators in which 10 steps at the slave robot arm equals one step at master. However, change of angle to change of angle control is desirable. The slave arm joints may have the same range of motion and axes as master joints. Thus, actuators in the slave robot arm 1162 may rotate the same number of degrees as the actuators in the master robot arm 1164. The scaling effect is provided by the different wedge angles.

[0214] In an example, the slave robot arm 1162 may have two wedges at a 30 degree angle with three actuators and 1010 wedges on the master robot arm 1164 at 3 degrees. The designer may choose the number of wedges to be driven. Thus, the operator holds the end effector, the arm extends, the angles detected by encoders and sent to the robot controller 1166.

[0215] In a series of three actuators, the first and third may rotate half the angle of the second actuator, but oppositely. A rotational command from the second actuator may cause the same angle rotation on the second master actuator. [0216] If the actuators in an arm are wired in series, to make only a half turn for the end actuators, a separate motor controller for the end actuators may be used or the drive signal may be conditioned by a device at the end actuator.

[0217] If three sets of wedges are used, the array would be able to rotate in any direction at any time. The neutral position would be with each set at 120 degrees to each other. Then one or more actuator sets can be rotated to bend the whole assembly in any direction.

[0218] If the wedges are greater angle than necessary for the desired assembly range of motion, they can be used at less than 180 degree rotation. They may allow using hard stops or possibly sprung stops between wedges for various effects such as using spring force to reduce the actuator torque when supporting off -plane motions with a payload.

[0219] A certain level of friction may be advantageous for stepper motor control because it prevents the actuators from jumping from step to step. With no friction, there is only inertia to prevent the actuator from jumping from one discrete step to the next. With a certain amount of non-stick-slip friction (such as is common to a preloaded roller bearing, or a sliding contact such as a Teflon™-on-Teflon™ sliding contact) there is a certain level of current that is required to overcome this friction. Embodiments of the actuators use magnetically preloaded bearings which provide the necessary non-stick friction to the actuator providing a smoother transition from step to step.

[0220] In another embodiment, ball bearings can be used in combination with a low friction surface combination between the stator and rotor such as, but not restricted to, in the airgap. Teflon on Teflon, for example, as very low stick-slip-friction and would allow smooth operation of the actuator in stepper mode by requiring a high level of torque from the actuator to overcome this friction. A materials Teflon has a unique characteristic which allows micro movements to be achieved through a variation of force on the movable structure which is rotationally or otherwise movably attached to the fixed member. Instead of stopping robot with change of direction, with change of direction command to actuator, all actuators may stop momentarily. [0221] In any stack of actuators and wedges disclosed in this patent document, in a given set of robot arm movements, a first movement stage may involve rotation of a first set of wedges, and a second movement stage may involve rotation of some or all of the first set of wedges. The wedges may be in counter-rotating pairs which are active in both the first movement stage and the second movement stage. In a specific example, the second movement stage may involve a smaller number of actuators and wedges, such as a single pair of wedges. For example, if the first movement stage involved rotation of 6, 8, 10 or 12 wedges, the second movement stage may involve a single pair of wedges counter-rotating relative to each other. Since involvement of each actuator may lead to a loss of precision in the robot arm movement, this method may allow increased precision in the second movement stage. In general, any movement stage could also be followed by additional movement stages, with each movement stage involving a different number of actuators, with corresponding lower or higher precision. A movement stage could correspond to a specific movement of a robot arm towards an object, and a subsequent movement stage could correspond to a subsequent movement, such as grasping or positioning an object. A movement stage could correspond to a time period, with different movement stages occurring during specified time segments. Opposite movement of the wedges may be equal angular amounts or speeds or different angular amounts or speeds.

[0222] The same principles of hand control controlling a rotary actuator may be applied to a linear actuator. For example, rotation angle of hand control may be sensed to drive a proportional displacement of any linear actuators downstream of the hand control For example, displacement of hand control may be sensed to drive proportional speed of any linear actuators upstream of the hand control.

[0223] In some embodiments, any number of wedges can be used, for example odd numbers can work, especially if there is a half angled wedge at the top and bottom. So for example, a 5 degree wedge at the bottom, a 10 degree wedge in-between, and a 5 degree wedge at the top works to increase mechanical advantage and to provide a controlled motion. Any other number of wedges will work as well.

[0224] Torque Amplifier [0225] A non-limiting exemplary embodiment of a torque amplifier 210 is shown in

Fig. 37 in plan view and in Fig. 38 in perspective view. The torque amplifier 210 in this embodiment is a gearing system having a sun gear 212, an array of first planet gears, which are here compound gears including larger gears 214 that mesh with the sun gear 212 and smaller gears 216, an array of second planet gears 218 that mesh with the smaller gears 216, and a ring gear 220 that meshes with the array of second planet gears 218. The smaller gears 216 and larger gears 214 here are fixed together to make up compound first planet gears, but the smaller gears 216 could be otherwise connected to the larger gears 214 to rotate with the first larger gears 214. Here, the sun gear 212 is an input which is fixed to a motor rotor and the ring gear 220 is an output. In this embodiment, the larger gears 214 and their associated smaller gears 16 are rotationally fixed to the housing 222 which in this exemplary embodiment comprises the back of a stator of an electric motor. The sun gear 212 as shown in Figs. 37 and 38 is under a cap 224 fixed to the housing 222. The cap 224 may serve as a connection between the back of the stator and a shaft 226 connected to another part of the housing, in this case an additional stator of the electric motor, as shown in Fig. 52. The second planet gears 218 in this embodiment of the device also do not orbit the sun relative to the housing. Rather, their rotational axis is in a fixed position relative to the housing. This eliminates the need for a planet carrier with the advantage of reduced complexity and the potential for high stiffness.

[0226] The term "planet" in this document does not imply that the planets orbit; rather it describes positioning, such as within a ring gear, around a sun gear, or contacting pairs of other planet gears.

[0227] In the embodiment shown, there are four of each of the first planet gears each comprising a larger gear 214 and smaller gear 216, and four second planet gears 218, but other numbers of gears could be used. Torque amplification is obtained by the sun gear 212 being smaller than the ring gear 220 and by the smaller gears 216 being smaller than the larger gears 214 of the first planet gears. The smaller diameter gears 216 are fixed to the top of the larger gears 214 which provides an additional gear reduction as the smaller gears 216 drive the array of second planet gears 218. The smaller gears 216 could also be, for example, under the first planet gears 214. The array of second planet gears 218 then drives the outer ring gear 220 (output). This set of second planets 218 is unique in that each gear floats in place and takes up any backlash with the use of an applied downward magnetic force, as described below.

[0228] A mechanism to allow the floating of the second planet gears 218 is illustrated in Fig. 39. As shown in Fig. 39, each floating gear 218 has three gear mesh contacts to position it in the XY directions; two first gear mesh positions marked by first arrows 228 where the floating gear 218 meshes with two smaller diameter gears 216 in the first planet stage, and one mesh position marked by second arrow 230 where the floating gear 218 meshes with the ring gear 220. The gear mesh in each of the above mesh positions prevents rotation of the floating gear around an axis that extends from the gear mesh to the rotation axis of the floating gear. The combination of rotational constraint on each of these three intersecting axes provides a fully constrained support of the floating gear with regard to its attitude relative to the housing. Each of the gears in this exemplary embodiment is tapered in a direction that allows axial loading of the floating gears to preload all of the gears in the load path between the sun gear and the ring gear. The downward (axial) force from the floating gear is transferred through the 1 ^st planet gear (which can also float axially) to the sun gear to remove backlash from all gear interfaces in load path from sun gear to ring gear.

[0229] By using a bearing on the 1st planet set that allows for a small amount of axial displacement, but ensures that the gear does not rotate about a horizontal axis out of plane, the applied downward magnetic force can be transferred from the floating 2nd planet 218 to the 1st planet, and then to the sun gear 212. This ensures that with the proper downward force on the floating gear/s, backlash in any of the gear interfaces is eliminated. The gear meshing areas, along with the bearing/bushing on the first planet axis, ensures that any moments generated from the offset axial forces do not cause the gear to rotate out of plane and cause additional problems with gear tooth meshing. This may be accomplished on the first planet gears by a pair of roller bearings or another style of bearing such as needle bearings which allow some axial movement. [0230] The tapered interface between the two first stage gears 214 and 216 forming first planets and the floating gear forming second planets 218, and between the output ring 220 and the floating gears, provides XY positioning when an axial preload is applied to the floating gear.

[0231] Axial preloading of the floating gear can be provided by a number of means including but not limited to a permanent magnet in the housing attracting a steel floating gear or permanent magnet in the floating gear, an electromagnet in the housing attracting a steel floating gear or permanent magnet in the floating gear, or a spring preload preferably acting against a bearing in the floating gear and with enough compliance to allow both axial displacement of the floating gear and XY displacement as the floating gear finds a best-fit position in the XY direction.

[0232] In the embodiment shown in Fig. 39, a magnet 232, which may be a permanent magnet or an electromagnet, attracts a steel second planet gear 218 which provides the axial force indicated by large arrow 234.

[0233] A permanent or electromagnet 232 between a housing 222 and each of the tapered floating 2nd planet gears 218 may provide a pre-load to the system in order to take up any backlash. Alternatively, a force may be mechanically applied to the top or bottom of the gear 218 to provide the downward force.

[0234] The second planet gear 218 may also have a magnet 256 as shown in Fig. 53.

In this way, the second planet gear 218 may be made of a non-magnetic material and still receive an axial force from permanent or electromagnet 232. In Fig. 53, a rotor 242 and housing 222 are shown. The housing component shown may be a stator depending on the embodiment, but electromagnetic elements for causing the rotor and stator to act as an electric motor are not shown.. In some embodiments a lower stator, not shown in this figure, may also be added. In the embodiment shown, the teeth of ring gear 220 have radial extensions 258 and the teeth of smaller gear 216 have radial extensions 260. These extensions help maintain engagement of the teeth in the event of radial misalignment of the gears. Such extensions may also be included in other embodiments. [0235] An example of a mechanical application of force is shown in Fig. 40. In this schematic example, a second planet gear 218, is on a shaft 236 instead of free floating. Components in this figure are not necessarily to scale. Springs 238 which are connected to the housing and to inner portions of bearings 240 which are slideably supported on the shaft; the inner portions of bearings 240 rotatably support outer portions of bearings 240 on which the second planet gears are mounted. The springs 238 push or pull on the bearings to apply the axial force to the second planet gear 218. In this schematic example, ring gear 220 is shown but the first planet gears and smaller gears are omitted. Another example is shown in Fig. 54. In this example springs 238 are connected to an upper portion 262 of housing 222 which is connected in this embodiment to the rest of housing 222 through the cap 224. A pivotable connection 264 connects the springs 238 to the floating planet gears 218. The springs could also connect to the floating planet gears from below, directly from the housing and could push or pull. In any embodiment, the axial force applied could be in either direction, with the tooth taper direction configured accordingly.

[0236] As shown in the schematic example in Fig. 40, the second planet gears need not be floating; they can also be on shafts 236 mounted on the housing so long as they are axially displaceable on the shafts. Having the gears floating provides the advantage of allowing them to find a best-fit position between the three contacts to compensate for size or position variations of elements. In another embodiment, the compound first planet gear sets comprising the larger gears 214 and smaller gears 216 could be floating and the second planet gears 218 fixed. In other embodiments, the second planet gears 218 could be compound gears and the first planet gears simple or compound. In a reducing gearbox with a sun gear as input and ring gear as output, the second planet gears being compound gears results in the larger gears of the second planet gears overlapping the ring gear. Either the second planet gears or the first planet gears may be floating gears.

[0237] In an embodiment, the gears of the compound gears may be axially movable but rotationally fixed with respect to one another, and connected for example by a spring. This may help balance the axial forces passing from the second planet to the first planet relative to those passing to the ring gear. Such balancing may also be accomplished by applying an axial force to the ring gear or sun gear.

[0238] In an embodiment, permanent magnets are combined with variable power electromagnets to provide an axial preloading force on the floating gears as well as an adjustable preload as a result of energizing the electromagnets. As a result, low gear friction can be achieved at low torque conditions for low backdrivability friction and low wear, while the axial preload can be increased under increased torque conditions to maintain a zero backlash characteristic at high torque levels where the axial reaction on the gears will be higher.

[0239] Tapered teeth ensure that backlash is taken up in either rotation direction. Any gap between gear teeth on either side of the tooth will allow the floating gear to displace axially until there is full engagement of the teeth, eliminating backlash. The floating gear is restrained in three places by the first stage planet gears and the ring gear such that no additional support is required. The gear centers itself in this position as a result of the applied downward magnetic force.

[0240] Any gear tooth profile may be used for the torque amplifier. An involute profile may be used in order to allow for some small deviation in the centre distance without negatively affecting the gear meshing. This ensures that when the floating planet gear moves axially or radially, the teeth mesh smoothly.

[0241] A mirrored helical tooth shape may be used a mirrored helical gear shape to achieve the tooth taper, although other methods may also be used. This mirrored helical design allows one side of each tooth to be cut with one helical operation such as by cutting with a gear tooth hob or shaping cutter, and the other side of the tooth to be cut with an opposite helical operation, resulting in a tooth that meshes smoothly, while allowing the taper to take up any gap in either rotation direction. An example of a mirrored helical tooth shape is shown in Figs. 41 to 44.

[0242] Fig. 41 shows a single exemplary tooth 250 on a floating gear 218. Other teeth would be present but are not shown. A corresponding tooth shape may be used on each of the other gears. Only gears that mesh need to have corresponding tooth shapes, so it is also possible for sun gear 212 and first planet gears 214 to use a different, non-corresponding tooth shape than smaller gears 16, second planet gears 218 and ring gear 220. Sections 2-2, 3-3 and 4-4 show planes corresponding to the views of Figs. 42, 43 and 44 respectively. Fig. 42 shows a cross-section of the front of the tooth 250. Fig. 43 shows a cross-section of the middle of the tooth 250. Fig. 44 shows a cross-section of the back of the tooth 250. The teeth and preload work together to eliminate backlash. The preload, whether created by a spring, magnet or electromagnetic or other biasing means, will pull the teeth so that the tapers of the corresponding teeth are brought into an engaging contact. The preload can push the floating gears away from the stator and other gear or pull the floating gears towards the stator and other gears, depending on the orientation of the corresponding tapers. It is preferable to have the planetary gears pulled towards the stator for assembly purposes.

[0243] In another embodiment of the tooth shape, the addendum and dedendum of the sun, planets and annulus are adjusted such that a tapered tooth effect is achieved without changing the aspect ratio. The details of this are described as follows and as shown in Figs. 45 to 51. In this embodiment, as shown in Fig. 45, the one side of a gear may have the tips of the gears extend farther, the change in extension of the gear tips over the thickness being a taper angle. The gear pitch however may remain constant over the thickness of the gear. The dedendum and addendum of the sun, planets, and annulus at the top of the taper and at the bottom of the taper may be determined using the change in the diameter required for a prescribed taper angle and gear body thickness.

[0244] Figs. 46 to 51 show further details of a design of a tapered gear tooth profile with such a taper angle. The design of the gear shown may be used with the torque amplifier shown in Figs. 37-39 or in other applications.

[0245] As shown in Fig. 46 and 47, there is a gear 100 having a plurality of teeth

102. The teeth are tapered so that a back end 106 of each tooth extends radially outward from the central axis of the gear further than a front end 104 of each tooth. Similarly, gaps 108 between each tooth are tapered. A back end 110 of each gap extends radially outward from the central axis of the gear further than a front end 112 of each gap. The addendum of each tooth, as defined by its sides 114 and 116 are shifted in accordance with the taper, as shown in more detail in Figs. 49 to 51.

[0246] Fig. 48 shows an exemplary sketch of a positive addendum shift profile and labeled notable diameters including addendum circle, pitch circle, base circle and dedendum (root circle) diameters.

[0247] Figs. 49 to 51 show the gear tooth profile at three points along the length of a tooth. Fig. 49 shows the shape of the addendum defined by lines A and B through the back 106 of each tooth. Fig. 50 shows the shape of the addendum defined by lines A and B through the middle of each tooth 102. Fig. 51 shows the shape of the addendum defined by lines A and B through the front 104 of each tooth. The midplane is used to define the tooth profile in its standard configuration. On either axial end of the gear, an addendum shift is completed, shifting the gear tooth upward or downward. Between these three planes, there is a linear interpolation of the gear tooth.

[0248] Typically, an addendum shift is completed across the whole gear length. By varying the addendum shift across the length of the tooth, and combining a conical taper of the gear tooth body, a tapered gear is created. When combined with a second tapered gear, using the same addendum shifts, the two gears mesh when the positive shift face of one gear meets the negative shift face of the other.

[0249] For each of the sun, planets, and annulus gears, the change in the addendum and dedendum due to the taper of the gear body resulted in variation of the tooth profile as different sections of the mathematical involute were used.

[0250] A tapered gear allows preloading by applying an axial load to the gear. This has the effect of eliminating backlash between the gears. Additionally, it allows a gear to be more easily injection moulded.

[0251] The taper angle of the body may be selected in coordination with the materials of which the gears are comprised such that the taper angle ensures the highest possible axial load but remains outside of the region considered self-locking.

[0252] The design can be tailored to provide the desired gearing ratio and outer diameter by adjusting the gear diameters and teeth numbers accordingly. [0253] The pitch diameter of each of the gears (in the case of a compound gear, the pitch diameter of each gear making up the compound gear) may be chosen to be constant across the respective thickness of the gear body. A pure mathematical involute may be used for the teeth on each of the gears in order to prevent backlash from originating as a result of the tooth profile.

[0254] Tooth tapers may be adjusted to match the axial deflection desired in the floating gear. In general, a higher tooth taper angle results in a smaller axial deflection of the floating gear for a given change in gap between gears.

[0255] Any material common to gears may be used for the construction of this torque amplifier. Examples include plastic and/or steel and/or bronze. Spinodal bronze may be used on alternate gears in order to allow operation in some applications without the requirement for additional lubrication. A magnetic material such as steel or iron may be used for the floating gear in order for it to respond to the magnetic field, generating the downward magnetic force necessary to preload the tapered gears and eliminate backlash.

[0256] The torque transfer device may be driven by a motor, as shown in Fig. 52.

The motor may be for example an axial motor comprising a double-sided rotor 242 with an upper stator 244 above and lower stator 246 below the rotor. The stators 244 and 246 together make up portions of housing 222. The double stator design minimizes the net magnetic force on the rotor. The magnetic force between the rotor and stators is reacted on both the inner and outer diameter of the motor at contacts between the two stators. In the embodiment shown, there is an annular contact 248 between stators near the outer diameter of the rotor 242 and the cap 224 serves as another contact. Shafts 252 for first planet gears 214 may be rigidly connected to the housing. First planet gears formed by larger gears 214 and smaller gears 216 may rotate on shafts 252 using bearings or bushings located for example as indicated by reference numeral 254. Second planet gears 218 are not shown in this figure.

[0257] In the claims, the word "comprising" is used in its inclusive sense and does not exclude other elements being present. The indefinite articles "a" and "an" before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A robot arm comprising:

a succession of segments, each successive segment of the succession of segments rotatably connected at a respective rotatable connection to a respective previous segment of the succession of segments, each respective rotatable connection defining a respective axis of relative rotation of the respective successive segment and respective previous segment; the respective axes being aligned generally with a longitudinal direction of the robot arm;

at least one middle segment being a successive segment with respect to a previous segment connected to the middle segment at a first rotatable connection of the respective rotatable connections and the middle segment being a previous segment with respect to a successive segment connected to the middle segment at a second rotatable connection of the respective rotatable connections, the middle segment being shaped so that the respective axes of the first rotatable connection and the second rotatable connection are not parallel to each other;

plural actuators arranged to drive relative rotation of the segments about the respective axes; and

the actuators having sufficient friction that any rotatable connections of the respective rotatable connections that are in positions having mechanical advantage above a threshold do not move when the actuators are not energized.

2. The robot arm of claim 1 in which the actuators have sufficient friction that the arm remains still when the actuators are not energized regardless of the position of the arm.

3. The robot arm of claim 1 or claim 2 in which the actuators each comprise a rotor and a stator rotatably connected by thrust bearings, the rotor magnetically attracted to the stator to produce a force borne by the thrust bearings.

4. The robot arm of any one of claims 1 -3 further comprising sensors to detect positions of the rotatable connections.

5. The robot arm of claim 4 in which the sensors detect index positions of the rotatable connections, a control system inferring the position of each of the rotatable connections from rotations made since a detection of an index position for each of the rotatable connections.

6. The robot arm of any one of claims 1 -5 in which every second one of the

asymmetrically shaped segments is controlled to rotate synchronously.

7. The robot arm of claim 6 in which the asymmetrically shaped segments other than the every second one of the asymmetrically shaped segments are also controlled to rotate synchronously.

8. The robot arm of claim 7 in which the asymmetrically shaped segments other than the every second one of the asymmetrically shaped segments are controlled to rotate oppositely to the every second one of the asymmetrically shaped segments.

9. The robot arm of any one of claims 1-8 in which at least one of the plural actuators comprises:

an electric motor having a stator and a rotor;

a sun gear, the rotor being connected to drive the sun gear;

a pinion shaft mounted on the stator; and

a pinion gear mounted on the pinion shaft and arranged to mesh with the sun gear.

10. The robot arm of claim 9 in which the at least one of the plural actuators comprises plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and the at least one of the plural actuators further comprising plural additional gears each arranged to mesh with two of the pinion gears.

11. The robot arm of claim 9 in which the at least one of the plural actuators comprises plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and a respective second pinion gear, and the at least one of the plural actuators further comprising plural additional gears each arranged to mesh with two of the second pinion gears.

12. The robot arm of claim 10 or 11 in which the at least one of the plural actuators further comprises a ring gear arranged to mesh with the plural additional gears.

13. The robot arm of any one of claims 10-12 in which the plural additional gears of the at least one of the plural actuators have tapered teeth and are biased axially.

14. The robot arm of claim 9 in which the at least one of the plural actuators further comprises a strain gauge arranged to measure a strain of the pinion shaft or of a structure surrounding the pinion shaft.

15. The robot arm of any one of claims 10-13 in which the at least one of the plural actuators further comprises a strain gauge arranged to measure a strain of at least one of the plural pinion shafts or of at least one structure surrounding a pinions shaft of the plural pinion shafts.

16. The robot arm of any one of claims 9-15 in which the at least one of the plural actuators further comprises a stepper motor controller connected to the electric motor for driving the electric motor.

17. A robot arm comprising: a succession of segments, each successive segment of the succession of segments rotatably connected at a respective rotatable connection to a respective previous segment of the succession of segments, each respective rotatable connection defining a respective axis of relative rotation of the respective successive segment and respective previous segment; the respective axes being aligned generally with a longitudinal direction of the robot arm;

plural actuators, each comprising a respective electric motor, arranged to drive relative rotation of the segments about the respective axes; and

a stepper motor controller connected to multiple actuators of the plural actuators, for driving the respective electric motors of the multiple actuators.

18. The robot arm of claim 17 in which every second segment of the succession of segments is arranged to be driven, in rotation relative to a respective previous segment, by a respective actuator of the plural actuators, each of the respective actuators arranged to drive the second segments being connected to receive a common input from the stepper motor controller.

19. The robot arm of claim 18 in which every first segment of the succession of segments is arranged to be driven, in rotation relative to a respective previous segment or relative to a base element, by a respective actuator of the plural actuators, each of the respective actuators arranged to drive the first segments being connected to receive an opposite input to the common input from the stepper motor controller.

20. A method of calibrating a robot arm as claimed in claim 4 or claim 5, the method comprising;

(a) selecting an actuator;

(b) moving the selected actuator into a default position or detecting that the selected actuator is already in a default position;

(c) selecting an additional actuator that has not yet been selected;

(d) moving the additional actuator into a default position or detecting that the additional actuator is already in a default position; and

repeating steps (c) and (d) until all of the actuators are in the default position.

21. An actuator comprising:

an electric motor having a stator and a rotor;

a sun gear, the rotor being connected to drive the sun gear;

a pinion shaft mounted on the stator;

a pinion gear mounted on the pinion shaft and arranged to mesh with the sun gear; and

a strain gauge arranged to measure a strain of the pinion shaft or of a structure surrounding the pinion shaft.

22. The actuator of claim 21 in which the pinion gear has tapered teeth and is biased axially.

23. The actuator of claim 21 or claim 22 in which there are plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and the actuator further comprising plural additional gears each arranged to mesh with two of the pinion gears.

24. The actuator of claim 21 or claim 22 in which there are plural pinion shafts mounted on the stator, each mounting a respective pinion gear arranged to mesh with the sun gear, and a respective second pinion gear to form a compound gear, and the actuator further comprising plural additional gears each arranged to mesh with two of the second pinion gears.

25. The actuator of claim 23 or 24 further comprising a ring gear arranged to mesh with the plural additional gears.

26. The actuator of any one of claims 23-25 in which the plural additional gears have tapered teeth and are biased axially.

27. The actuator of any one of claims 21-26 further comprising a stepper motor controller connected to the electric motor for driving the electric motor.

28. An actuator comprising:

an axial flux motor; and

a planetary gearbox connected to an output shaft of the motor, arranged to amplify the torque output by the motor;

wherein a force is exerted on a rotor of the axial flux motor to force the rotor against a thrust bearing.

29. The actuator of claim 28, wherein a gear of the planetary gearbox is magnetically attracted to a rotor of the motor.

30. The actuator of claim 28 or 29, wherein a gear of the planetary gearbox is arranged to rotate about a shaft or bore formed integrally with the stator of the motor.

31. A succession of segments, comprising: at least three interconnected segments, comprising: a first segment, rotatably connected to a second segment, and

a third segment, rotatably connected to the second segment,

wherein the first segment is rotatable relative to the second segment about a first axis and the second segment is rotatable relative to the third segment about a second axis, the first and second axes being non-parallel, and

wherein each segment comprises an actuator according to claim 28, 29 or 30.

32. The succession of segments of claim 31 , wherein internal friction of the thrust bearing of the motors prevents movement of the segments due to the weight of the segments alone when no power is supplied to the motors.

33. The succession of segments of claim 31 or 32, wherein each of the segments is substantially identical.

34. A robotic joint having a succession of segments according to any one of claims 31, 32 or 23.