WO2002061523A1

WO2002061523A1 - Multiple degrees of freedom control device

Info

Publication number: WO2002061523A1
Application number: PCT/SG2001/000014
Authority: WO
Inventors: Alain Dupuis
Original assignee: Realistix Laboratories Pte Ltd
Priority date: 2001-01-30
Filing date: 2001-01-30
Publication date: 2002-08-08

Abstract

The present invention provides a control device which provides signals indicative of components of movement in two or more different degrees of freedom, including: (a) a base unit; (b) a control lever movable relative to the base unit; (c) a movement sensor associated with each degree of freedom which detects a component of movement of the control lever relative to the base unit where all of the movement sensors are located in the base unit; (d) a directional translator that translates a component of movement in a first one of the degrees of freedom into a movement in a second of the degrees of freedom, such that a component of movement in the first of the degree of freedom is measured by a sensor measuring movement in the second degree of freedom.

Description

MULTIPLE DEGREES OF FREEDOM CONTROL DEVICE

Field of the Invention

This invention relates to a multiple degrees of freedom control device and to an articulated device with multiple degrees of freedom. It relates particularly but not exclusively to a control device which monitors the movement of a control lever relative to a base and provides signals indicative of that movement to a computer or other command device, the control device optionally incorporating a force-feedback mechanism, capable of applying a force to an operator or appliance. The invention also relates to an articulated device which is capable of articulation in two or more degrees of freedom and to the design of a casing for the control device which substantially dispenses with the need for screws in its assembly.

Background to the Invention

A computer control device is used for transmitting data into a computer. For computer and video games it is desirable that the control device be designed to provide the user with a superior gaming experience. A common type of device used in video games is a joystick, which in its most common form consists of a base and a control lever which is movable relative to the base. Typically, the operator moves the lever to control objects and select characters which are presented on a video or computer display screen. The software running the application processes input signals which are received by the computer from the joystick, and uses the data to alter the outcome of a gaming scenario.

To maximise the interactive nature of computer and video games, a new type of joystick has recently become available. When this new type of joystick is used to play a computer game, the game's software can manipulate input from the joystick to provide feedback to the joystick. This feedback is used to instruct small motors inside the joystick assembly to generate a force within the control lever that is applied through the lever to the gaming operator. Known as force- feedback, the ability of the joystick to apply a force to its operator depending on a particular gaming scenario has further enhanced the interactive quality of video and computer gaming. Until recently, the movement of the joystick's control lever has been limited to two degrees of freedom. For example, the joystick operator could only move the control lever forward and backward or left and right. Other movements in a third dimension (such as jumping) were often facilitated by way the operator activating a button. In order to improve the gaming experience and maximise three dimensional software technology, manipulation of characters in a third degree of freedom has been proposed as in US Patent application 6,030,291. This document discloses a device in which three sensors are used to determine the position of characters, each sensor providing input to the computer regarding a different degree of freedom. This has increased the manoeuvrability of the control lever relative to the base unit and the resultant control that the gaming operator has over the characters and parameters presented in the game.

This type of gaming device can be expensive and bulky, depending on the nature of the sensors and other components that have been used in the device's assembly. Prior art in the field of three dimensional joysticks employs three movement sensors, each of which is necessarily located along an axis around which the movement occurs. This implies that in addition to two sensors located in the base unit of the device to detect backwards/forwards and sideways movement, it is necessary for a third sensor to be located in the axis of the control lever itself, to detect rotational movement of the lever.

The use of joysticks is not limited to computer and gaming applications. Joysticks or directional control devices are also used to control cranes, machine tools and other larger scale mechanically based devices. Benefits of using a joystick-type device in these applications include an increase in the precision with which these often large devices are moved and a decrease in the associated risk and cost of operation. Directional control devices such as joysticks also have potential for use in many areas of automated production and transport as well as in the remote control of objects. However, usage of this technology to date has been limited because of the cost and restriction in the directional flexibility of current devices.

Marketability of such a directional control device depends on its affordability. It is necessary that the joystick retails at a reasonable price; hence the components used in its production must not exceed a predetermined cost. This in turn limits the selection of sensors that can be used in the joystick to ones which are usually cheaper, and bulkier as a result. Very small microsensors which are capable of detecting movement are available, however they are expensive and not commonly used in joystick technology. The sensors used in traditional joysticks are generally larger and as in the prior art, located along the axis of the movement that they are detecting. A sensor used to detect movement of the control lever about an axis that is perpendicular to the base must, therefore, be located inside the casing of the lever itself. This restricts the design parameters of the joystick, as the control lever must be large enough to contain one movement sensor.

Present assembly of a joystick requires screws to hold sections of the casing together, resulting in a complicated manufacturing process. This in combination with the cost of the screws itself raises the production cost of the joystick which should be minimised to maintain accessibility of the device to a wide range of computer and video game players.

Summary of the Invention

According to a first aspect of the present invention, there is provided a control device which provides signals indicative of components of movement in two or more different degrees of freedom, including:

(a) a base unit;

(b) a control lever movable relative to the base unit;

(c) a movement sensor associated with each degree of freedom which detects a component of movement of the control lever relative to the base unit; (d) a directional translator that translates a component of movement in a first one of the degrees of freedom into a movement in a second of the degrees of freedom, such that a component of movement in the first of the degrees of freedom is measured by a sensor measuring movement in the second degree of freedom. It will be appreciated that the invention may be used to provide a control device which is more compact and less expensive to produce than other such devices with similar functionality. This is achieved by way of a directional translator, which translates a component of movement in one degree of freedom into a component of movement in a different degree of freedom. Preferably, all of the movement sensors are located in the base unit. It will also be appreciated that the orientation of the control device is not necessarily with the base oriented toward a surface and the shaft extending upward. The control device may be inverted, turned sideways or oriented in any other direction which is appropriate for a particular application.

The degrees of freedom measured by the movement sensors may be any suitable degrees of freedom. They may relate to translational movement, rotational movement, or any combination. For example, one of the degrees of freedom may be rotational movement about an axis, whilst another may be translational movement forwards or backwards in a particular direction. In a preferred form of the invention, the control device provides signals indicative of rotational movement about three substantially orthogonal axes, and one or more movement sensors sense rotational movement about each axis. As an optional feature, the position of the control lever may be adjustably fixable along one of the axes.

In a preferred arrangement of the invention using the mutually perpendicular conventional coordinate axes, X, Y and Z, rotational movement around the Z-axis is translated into a rotational movement around the X-axis; hence the sensor for that component of the movement can also be oriented along the X-axis. If the invention takes the form of a traditional joystick detailed by a base and protruding lever where the orientation of the base is along the X- and Y-axes and the control lever extends along the Z-axis, the sensor responsible for detecting movement around the Z-axis can also be oriented along the X-axis or the Y-axis inside the base of the device. This effectively reduces the size of the control lever, since it is no longer necessary for the control lever to house a sensor, thereby facilitating a more compact control device.

Any suitable number of movement sensors may be used. The preferred number is one for each axis of movement. However, more than one sensor may be used for any axis of movement, and, with appropriate multi-tasking controls, one sensor may be used to measure more than one axis of movement.

More than one directional translator may be used. Two or more directional translators may be used to translate a component of movement in the first degree of freedom into a component of movement in the second degree of freedom. Further, one directional translator may be used to translate a component of movement in a first degree of freedom into a component of movement in a second degree of freedom, and another directional translator may be used to translate a component of movement in a third degree of freedom into a component of movement in the second degree of freedom, so that movement relative to all three degrees of freedom is measured by measuring movements relative to one degree of freedom.

The directional translator may have any suitable shape and configuration. It may use electrical or mechanical means to achieve its directional translation. One suitable type of directional translator is an arrangement of gears. Another suitable type of directional translator is a cam and yoke arrangement.

It is preferred that the range of sensors employable for the detection of components of movement of the control lever includes but is not limited to potentiometers, switches, encoders or any combination thereof. As an optional feature of the invention, the control device may further include one or more motors which apply a force to the control lever. The force applied to the control lever may be the sum of components of forces generated by motors associated with each of the degrees of freedom such that the force applied to the control lever is independently adjustable for each of the degrees of freedom. The control device may further include a force directional translator that translates a component of force generated by a motor in a first one of the degrees of freedom into a component of force in a second of the degrees of freedom. There may be two or more motors generating components of force in the same degree of freedom, with one or more of these components of force being translated into one or more components of force in one or more different degrees of freedom by means of one or more directional translators. Again, it will be appreciated that the invention may employ more than one control device connected in series or daisy-chained together to provide potentially unlimited flexibility in the directions in which a force can be applied through the control device.

According to a second aspect of the present invention there is provided an articulated device which is capable of articulation in two or more degrees of freedom including: (a) a reference unit;

(b) at least a first movable unit which moves in the two or more degrees of freedom relative to the reference unit;

(c) at least one force generator which applies a force to the first movable unit;

(d) at least one directional translator which translates the direction of a force in a first degree of freedom into a force which is in a second degree of freedom, such that a component of movement which is generated in the first degree of freedom is applied in the second degree of freedom. The articulated device may employ a plurality of movable units, each connected in series or daisy-chained together. Each movable unit then becomes movable relative to an adjacent movable unit, such that the degrees of freedom of movement for one movable unit in the chain may be entirely different to the degrees of freedom of movement for another movable unit in the chain. This provides potentially unlimited flexibility in the combination of degrees of freedom in which the joints of the articulated device may move. Applications for this configuration of the articulated device include robotics, transport, automated and keyhole surgery and any other tasks in which flexibility and control are essential. The force generator which generates the force that is applied to the movable unit is not necessarily contained within the moving unit. A directional translator which is identical in principle to the directional translator comprised in the first aspect of the present invention, translates a force in one degree of freedom into a force in another degree of freedom by way of a cam and shaft or gears, as previously described. This enables the force generator to be distanced from the movable part of the articulating device, preferably so that it is located within the reference unit, or a movable unit which is adjacent to the unit which is moving. This has applications where the moving parts of the articulating device are necessarily small and cannot physically contain a force generator.

It is preferred that the principle of operation of force generators employable for the generation of forces to be applied to the movable units includes but is not limited to mechanical, magnetic, elastic, gravitational or hydraulic, or any combination of these. While several force generators may be used to generate forces which are applied to a movable unit in more than one degree of freedom, more than one force generator may also be used to move a movable unit in only one degree of freedom. It is also preferred that the force applied to one or more movable units is the sum of two or more forces which are applied in two or more degrees of freedom and which are generated by one or more force generators.

In another embodiment of the invention, two or more sensors are included in the articulated device which detect components of movement in two or more degrees of freedom. These sensors may be located along the axis along or around which the movement occurs. Alternatively, the sensors may be located along a different axis, but may use a directional translator to detect the movement. Using the sensors to detect the positioning of the articulated device facilitates feedback which may be necessary in automated and remotely controlled procedures to ensure that the device is in fact achieving the desired outcome and to make corrections if it is not. Sensors also enable the procedures being performed by the articulated device to be monitored and/or recorded.

According to a third aspect of the present invention, there is provided a control device wherein the casing of the device is designed such that it is assembled substantially without screws.

Brief Description of the Drawings

The invention will now be described in greater detail with reference to the drawings which show example forms of the invention. It is to be understood that the particularity of the drawings does not supersede the generality of the preceding description of the invention.

Figure 1 is an exploded perspective view of components of a core assembly of a control device according to one embodiment of the invention.

Figure 2 is an underside perspective view of the device of Figure 1 when assembled.

Figure 3 is a cross-sectional view of the device of Figure 2, taken along the line Ill-Ill.

Figure 4 is a schematic diagram of the device according to one arrangement with a fixed support. Figure 5 is a schematic diagram of the device according to an arrangement with a mobile support.

Figure 6 is a schematic diagram of the device according to an alternative fixed support configuration. Figure 7 is a schematic diagram of the device according to an embodiment which incorporates force feedback.

Detailed Description of the Drawings

Figure 1 illustrates the components of a core assembly of a control device according to one embodiment of the invention. There is a shaft 1 into which a compression spring 11 and a plunger 5 are inserted. A core casing 2 slides over shaft 1 which forms the core of the control lever or joystick used by the game player. A washer 7 sits on top of core casing 2 and an optional pin 12 holds the casing 2 and washer 7 in place with respect to the shaft. The left middle casing 3 slots onto an arm protruding from the core casing and a torsion spring 10 slots onto an arm on the opposite side of the core casing followed by the right middle casing 4. Washers 9 (only one of which is illustrated in figure 1 ) sit over the protruding articulating surfaces of middle casings 3 and 4 holding them together. External casings 6 (only one of which is shown in figure 1 ) are placed over the middle casings 3 and 4. The space defined between casings 3, 4 and 6 is all part of the base unit.

A yoke cam 8 sits over another cylindrical extension of right middle casing 4, on the opposite side of shaft 1 to that on which the torsion spring 10 is located. Yoke cam 8 is used to translate a component of rotational motion around the Z-axis (twist) into a rotational movement around either the X-axis or the Y- axis. This translation is effected by co-operation between projection 13 on shaft 1 and vertical walls 14 on the lower part of yoke cam 8. When shaft 1 is twisted, projection 13 presses against one or other of walls 14, imparting to yoke cam 8 a rotational movement one way or the other about the axis defined by the arms of core casing 2. Thus, in effect, a rotation about a vertical axis is translated into a rotation about a horizontal axis.

The operation of yoke cam 8 can be observed in greater detail in Figure 2, an underside view of the partially assembled device, where projection 13 from shaft 1 is shown clearly inserted between walls 14 of yoke cam 8. Twisting of shaft 1 one way or the other causes projection 13 to press against one or the other of walls 14, inducing a rotational movement in yoke cam 8 about a horizontal axis. This movement is measured by potentiometer 15.

The operation of potentiometer 15 is shown in greater detail in the cross- sectional view provided by Figure 3. Rotational movement of shaft 1 about its vertical axis 1 induces rotational movement in yoke cam 8 about the horizontal axis on which potentiometer 15 resides. Potentiometer 15 measures the degree of rotational movement of yoke cam 8 induced by rotational movement of shaft 1 , while potentiometer 16, which is on the same axis as potentiometer 15, measures tilt of the shaft about a horizontal axis. A third potentiometer (not shown) measures sideways angular movement of the shaft about another horizontal axis.

Figure 7 illustrates one embodiment of the core of the device, incorporating motors Mx, My and Mz which are used to generate the force that is applied through the control device. In Figure 7, a gear 17 is driven by motor Mx, and transmits the motion of Mx to gears 18. These gears 18 further transmit the motion of Mx to a gear 19 which drives the core casing 2. The middle casings 3 and 4 are driven directly by a motor My. A gear 20 is driven by motor Mz and a series of gears 21 transmit the motion of Mz to a subsequent gear 22, which drives the shaft 1. It is preferred that the gears 17 to 22 are designed such that the size of the mechanism is reduced.

Figure 4 is a schematic drawing illustrating an embodiment of the device which has three sensors 26, 28 and 29. Sensor 28 detects angular movement about the Y-axis. Sensor 29 detects angular movement about the X-axis. Sensor 26, which is used to measure a component of angular movement about the Z-axis, is mounted along the Y-axis in line with Y-axis sensor 28. In this particular embodiment, the device is housed on a fixed support.

Figure 5 is a schematic drawing illustrating the core of the device according to a slightly different embodiment, wherein the support is mobile with respect to the outer casing of the core of the control device. The mobile support enables variation in the pretensioning of spring 10, as well as variation in the distance between the support and the center of motion of the control device. This facilitates adjustment in the recoil effect which is incident on the shaft. As in Figure 4, Z-Axis sensor 26 is mounted along the Y-axis. Figure 6 is a schematic drawing illustrating the core of the device according to yet another embodiment. In this embodiment, as was the case for Figure 4, the device is mounted on a fixed support. However, the sensor used to measure a component of angular movement about the Z-axis is mounted along the X-axis, in line with the X-axis angular motion sensor, rather than being mounted along the Y-Axis.

Figure 7 which illustrates one embodiment of the core of the control device incorporating motors, also illustrates one embodiment of the articulating device which forms another aspect of the invention. Motors Mx, My and Mz are used to generate forces which are applied through the articulated device to the moving unit (shaft) 1 in three degrees of freedom. Force generator, Mx generates a force which drives gear 17 and is transmitted to gears 18, which further transmit the force generated by Mx to gear 19. Gear 19 drives core casing 2 which encases a portion of moving unit 1. The middle casings 3 and 4 may be driven directly in a second degree of freedom by force generator My or may be driven by force generator My in an alternative degree of freedom which is translated into a force which is in the second degree of freedom via a directional translator such as a gear or yoke and cam as previously described. In a preferred embodiment of the invention, gear 20 is driven by motor Mz and a series of gears 21 transmit the motion of Mz to a subsequent gear 22, which drives the moving unit 1 in a third degree of freedom.

It is to be understood that although previous use of the notation Mx, My and Mz has referred explicitly to the use of motors, the use of Mx, My and Mz in the description of the articulated device includes but is not limited to motorised force generators. The term force generator refers to any device which generates a force that can be applied to a movable unit whether the force generated uses mechanical, magnetic, elastic, gravitational or hydraulic means, or any combination thereof.

The selection of a particular force generator to be used in an application of the articulated device depends on several factors which include the environment in which the articulated device will be used and the magnitude and precision of the force which is to be applied. In a heavy machinery or large- scale transport application, the noise produced by the force generating device is not likely to be of great importance; therefore a motorised force generator which generates noise would be acceptable. However, in an application where a remotely controlled articulated device is used in a surgical environment, there may be noise constraints; therefore a low-noise force generator may have to be used. Similarly, if a heavy object was to be positioned using the articulating device, the force generator must be able to generate a large enough force in the required degrees of freedom to achieve this. In the surgical example, the articulated device may only be required to move small segments of tissue which weigh less than a gram. The precision of the force applied by the force generator and interference that its operation may have with the environment must also be considered.

It is to be understood that various alterations, additions and/or modifications may be made to the parts previously described without departing from the ambit of the present invention.

Claims

1. A control device which provides signals indicative of components of movement in two or more different degrees of freedom, including: (a) a base unit;

(b) a control lever movable relative to the base unit;

(c) a movement sensor associated with each degree of freedom which detects a component of movement of the control lever relative to the base unit;

(d) a directional translator that translates a component of movement in a first one of the degrees of freedom into a movement in a second of the degrees of freedom, such that a component of movement in the first of the degree of freedom is measured by a sensor measuring movement in the second degree of freedom.

2. A control device according to claim 1 wherein all of the movement sensors are located in the base unit.

3. A control device according to claim 1 wherein the control device provides signals indicative of rotational movement about three substantially orthogonal axes, and one or more movement sensors sense rotational movement about each axis.

4. A control device according to claim 1 wherein the movement sensors are switches, potentiometers, encoders or any combination thereof.

5. A control device according to claim 3 wherein the position of the control lever is adjustably fixable along one of the axes.

6. A control device according to claim 1 which includes sensors sensing movement in three degrees of freedom, and a second directional translator, such that a component of movement of the control lever in the third degree of freedom is translated into a movement in the second degree of freedom, with the result that movements of the control lever in all three degrees of freedom are measured by sensors detecting movement in one of the degrees of freedom only.

7. A control device according to claim 1 further including one or more motors which apply a force to the control lever.

8. A control device according to claim 7 wherein the force applied to the control lever is the sum of components generated by motors associated with each of the degrees of freedom such that the force applied to the control lever is independently adjustable for each of the degrees of freedom.

9. A control device according to claim 8 further including a force directional translator that translates a component of force generated by a motor in a first one of the degrees of freedom into a component of force in a second of the degrees of freedom.

10. A control device according to claim 9 wherein two or more motors generate components of force in the same degree of freedom, but one or more of these components of force is translated into one or more components of force in one or more different degrees of freedom by means of one or more directional translators.

11. A control device according to claim 1 wherein the casing of the device is designed such that it is assembled without screws.

12. An articulated device which is capable of articulation in two or more degrees of freedom including:

(a) a reference unit;

(d) at least one directional translator which translates the direction of a force in a first degree of freedom into a force which is in a second degree of freedom, such that a component of movement which is generated in the first degree of freedom is applied in the second degree of freedom.

13. An articulated device according to claim 12 further including a second movable unit which moves in two or more degrees of freedom relative to the first movable unit.

14. An articulated device according to claim 13 including one or more further movable units connected in series to the first and second movable units, wherein each movable unit moves relative to an adjacent unit in two or more degrees of freedom.

15. An articulated device according to claim 12 wherein the force applied to one or more movable units is the sum of two or more forces which are applied in two or more degrees of freedom and which are generated by one or more force generators.

16. An articulated device according to claim 12 wherein the force generators apply a force which is generated: (b) using a motor;

(b) magnetically;

(c) elastically;

(d) gravitationally;

(e) hydraulically; or (f) using any combination of the above.

17. An articulated device according to claim 12 wherein two or more sensors detect components of movement in two or more degrees of freedom.

18. An articulated device according to claim 17 wherein the sensors are located along the same axis as that around which rotation of the movable unit occurs.

19. An articulated device according to claim 12 wherein the casing of the device is designed such that it is assembled without screws.