GB2273282A - Manipulator assembly - Google Patents

Abstract

Disclosed is a variable geometry structural member in the form of a manipulator assembly or module (10). The manipulator assembly or module (10) may be a stand alone unit or a unit to be affixed to a limited degree of freedom industrial manipulator. Manipulator assembly or module (10) comprises a series of linkages (13, 13A, 14A, 14B, 14C) pivotally, telescopically or otherwise interconnected to provide the desired degrees of freedom of movement of a structural connection plate (16) or grippers (15). Hydraulic lines are provided within the manipulator assembly to communicate hydraulic pressure not only to actuators which cause pivoting or movement of the various linkages, but also to provide controlled hydraulic pressure to an apparatus which might be attached to said structural connector plate (16) eg. the grippers (15). The manipulator is controlled by solenoid valves and has an anti-back lash and positive actuator locking valve arrangement to lock the fluid in the actuators to prevent positional drift. <IMAGE>

Description

POWERED VARIABLE GEOMETRY STRUCTURAL UNIT The present invention relates to the general field of load handling devices and industrial manipulators.

A large number of load handling and manoeuvring structures, such as knuckle boom cranes, industrial manipulators and so on are well known in the art. Many such structures, henceforth called manipulation arms or manipulator booms, are formed from a series of structural elements joined mechanically in series by simple hinge or more complex joints. By changing the length of a hydraulic ram that passes across a hinge joint, for example, the geometry of that joint can be altered in terms of the number of degrees it is opened or closed. By use of a series of individual joint actuators, the overall geometry of the manipulator boom can be altered widely and a payload thereby deployed throughout a large volumetric space. In complex manipulators, other types of joints such as sliding and roll joints may be required.

Currently known forms of large industrial manipulator booms suffer from a number of disadvantages or limitations.

For example, they are very expensive to create as unique items, especially where large loads are required to be manipulated at large reaches, or where complex multi degree of freedom high performance manipulation arms are required.

They are generally lacking in versatility in that the range of tool systems or end of limb devices is generally severely limited.

Another problem of the prior art industrial manipulator booms is that there is no boom mounted provision for controlled fluid pressure output to a device which might be attached to and supported by the boom. Such implements are normally provided with their own pneumatic, electric or hydraulic inputs, quite remote from the actual boom itself.

It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide an improved powered variable geometry structural unit.

According to the present invention, an apparatus comprises: a first structural connection means, a first element attached to or formed integrally with said first structural connection means, a second element connected by connection means to said first element, said connection means providing at least one degree of freedom of movement of said second element relative to said first element, a second structural connection means attached to or formed integrally with said second element, a power inlet to said apparatus, remotely controllable actuation means operatively associated with said power inlet to affect or prevent movement of said second element relative to said first element, and functional element and circuitry means for modifying the control, mechanical and motion response and/or mechanical response and/or motion response of the actuation means during normal load driving, load driven and stress reversal situations.

An example of a "functional element" is an hydraulic or pneumatic valve.

Preferably, the valve and circuitry means provides for positive locking of the element joints into position, such action being either automatically or discretionarily invocable or both.

Preferably, the apparatus comprises further elements connected in series, by at least one degree of freedom powered motion joints, to said first and second elements.

Typically, four only elements are used and three orthogonally disposed pivotal motion axes are provided so as to generate an integrated wrist type unit which provides motion in pitch, yaw and roll.

Typically, one or more of the actuator means comprise linear actuators operating through rack and pinion actuation systems optionally provided with anti-backlash control systems.

Preferably, remotely operable means are provided for discretionary locking of one or more of the motion joints.

Preferably, one or more of the elements is telescopic.

Preferably, the apparatus further comprises a plain or controlled power outlet operatively associated with said power inlet for providing plain or controlled power to a device that might be attached to said structural connections means and wherein the controlled power outlet may be further coupled to remotely controllable power control.

Preferably, the apparatus further comprises link circuitry and/or duct means integrally with or through said first, second and any other elements to provide a means of power services and/or electric communication therethrough.

Typically, the power inlet is provided in single mode hydraulic, pneumatic or electrical form or in mixed or multiple input form.

Preferably, the plain or controlled fluid pressure outlet is a hydraulic outlet and the apparatus further comprises power outlet means provided in mixed hydrostatic, pneumatic or electrical power form.

Beneficially, the apparatus further comprises a centrally located open conduit through which a number of disparate utility service systems may be removably accommodated.

Preferably, supply to said fluid pressure inlet is provided by a singular pair of uncontrolled pressurised hydraulic fluid or pressurised pneumatic fluid supply and return lines.

In a preferred form, a structural system may be made up from a number of specialised sub-systems or functional "modules" with it being specifically advantageous to combine a three orthogonal axis motion unit into an integrated "wrist" type unit offering motions in pitch, yaw and roll, which may operate as a stand-alone system or be combined with other modules such as "shoulder" or "arm" modules to yield a compound system. That is, in addition to said first and second movably interconnected elements, third and fourth movably interconnected elements may be connected in series to provide numerous degrees of freedom of movement between said first structural connection means and said second structural connection means.

Typically, the apparatus may be employed as a supplementary attachment to an existing limited degree of freedom industrial manipulator.

Preferably, said connection means comprise pivot pins and hydraulic rams wherein for example said first and second elements are pivotally interconnected by a pivot pin and mutually interconnected by a hydraulic ram to effect pivoting.

Alternatively, a rack and pinion system may be employed at each connection. That is, for example, two racks may be arranged to engage against a pinion, the racks being substantially parallel to each other and lying in a common plane.

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a schematic perspective view of a manipulator, showing a wrist unit connected to an arm unit, which is in turn connected to a shoulder unit; Fig. 2 is a side elevational view of a preferred form of wrist actuator unit with an external cover removed showing some internal details; Fig. 3 is a plan view of the wrist actuator unit of Fig. 2; and Fig. 4 is a schematic hydraulic circuit diagram depicting remote controlled valves and actuators in series in a multi link assembly.

In Fig. 1 there is schematically depicted the separate units of a manipulator generally at 10. The manipulator comprises a first structural connection means and shoulder actuator 12, an arm actuator unit 13 and a wrist actuator unit 14. Shoulder actuator 12 may be connected to a limited degree of freedom industrial manipulator, or simply attached to a fixed or mobile mounting point. The shoulder unit comprises a hydraulic actuator and is capable of rotating a device or actuator attached to it about a pivot axis P. The arm unit 13, which may be attached to the shoulder unit 12, is adapted to swivel whatever is attached to it about pivot axis Q. A facility in the arm unit 13 is provided to extend a forearm 13A backwards and forwards in the direction of the double headed arrow R.

The wrist unit 14 comprises three sub-units: the yaw actuator 14A, the roll actuator 14B and the pitch actuator 14C.

The roll actuator 14B pivots about axis T whereas the yaw actuator 14A pivots about axis S. In turn, the pitch actuator 14C pivots about axis U.

A pair of end effector grabs 15A and 15B are attached to a structural connection means 16 which is supported by pitch actuator 14C.

It should be appreciated that any number of elements may be located between shoulder unit 12 and connection means 16. That is, any number of degrees of freedom of movement may be employed depending on the number of elements connected in series. An hydraulic fluid pressure inlet is to be provided at some point on manipulator 10.

Generally, the hydraulic fluid pressure inlet will be provided at shoulder unit 12. Hydraulic lines would be provided within or upon each of the linkage members to hydraulically power manipulation of the device upon remote control. Hydraulic fluid from the same source would also control. Hydraulic fluid from the same source would also be available at a controlled fluid pressure outlet, preferably provided at structural connection means 16.

Hydraulic lines may then be directly tapped to a device such as the end effector grabs 15A and 15B as shown to be exemplary.

Referring to Figs. 2 and 3, a hose mounting plate 30 is contained in a telescopic arm inside a protective cover (not shown). The plate 30 mounts the wrist 14 onto the arm 13 or forearm 13A. A flexible hose is passed into a region between a yoke 32. The yoke 32 can rotate about the yaw axis as shown. Racks are contained within the housing 34.

Axially drilled ducts pass through a narrow neck connection 32A between the yoke 32 and "hand" 35. Valves 37 and 37A correspond to valves controlling the roll action. A control box (or boxes) 39 houses further valves and hydraulic circuit elements. These elements and associated hydraulic fluid distribution lines act to provide a number of simple and advanced control features to the wrist unit.

Included in the hydraulic circuitry controls that are preferably provided are pilot pressure operated loadholding or pilot operated check valves such as are required to cater for failure of the main fluid pressure supply and/or electrical signalling power, overcentre and counterbalance valves and associated circuitry for load run-away control and load sinkage control on active hold, valving and circuits to prevent hydraulic fluid cavitation under sub vapour-pressure operating pressure condition, fine pilot-pressure adjustment circuits and so on. Various components are additionally needed to control cross-talk between hydraulic channels and control of slow creep-underpower phenomena.

Additionally included here, is a remotely operable, solenoid type, anti-backlash and actuator locking valve and associated circuit system that operates firstly to drive an object into position with one actuator and thence to arrange that another actuator operates to exert a vectorially opposite directional force on the object to that being exerted by the actuator that drove the object to its position initially. Thence in further joint locking action the valves operate to introduce fluid into the end chambers of the operating and non-driving cylinders at a joint and thence to positively lock this fluid into these chambers such that no motion of the actuator is possible since no fluid may drain from either end of either drive cylinder. On release of the valve the actuator becomes unlocked.

In a preferred arrangement this "backlash lockout system" is comprised of a number of hydraulic logic valves, load release and load holding valves and pilot line circuits, operating in conjunction with the main actuator control spool valves. It is engaged by an electric solenoid valve operated in on-off mode by toggle switch from a remote control console panel. Lockout facilities may be provided for all or only some of the system's motion axes. All the valves may be solenoid type valves enabling remote control of the actuator as desired.

Racks 31A and 31B are shown extending beyond the housing in the plan view. Further racks 40A and 40B together with rack 41 provide roll motion and yaw motion respectively. It should be appreciated that each of the racks is associated with a corresponding pinion and are to be actuated hydraulically in a conventional manner.

Structural connection means are provided in pitching member 41 (Fig.2) Referring now to Fig. 4, a schematic hydraulic circuit diagram is depicted. A fluid pressure inlet 44 is provided at any convenient location, typically at shoulder unit 12.

Extending in parallel hydraulic engagement with fluid inlet 44 is a number of remote controlled valves 40 and corresponding actuators 42. Each control valve 40 and associated actuator 42 corresponds to a link in the manipulator assembly, whether it be a pivot link, telescopic link or otherwise. Typically, actuator 42 is associated with a rack. Alternatively, one or more of actuators 42 may be an hydraulic ram extending between joined arm members. Also connected in parallel with hydraulic inlet 44 is a further remote control valve 41 to provide controlled fluid pressure at outlet 43. Outlet 43 as mentioned earlier would typically be provided at structural connection means 16. The actuators and valves may be also connected in series or in series/parallel in accordance with general open and closed circuit hydraulic circuitry practice.

Also located at 16 might be a controlled electrical output socket, pneumatic output means and the like.

Control valves 40 and 41 may be locally controlled manually or may be controlled from a distance by way of radio controllers or otherwise.

Upon operation, valves 40 and 41 and supplementary valving (control box 39) may be activated so as to render the members locked into any desired position.

It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention.

For example, the system may be provided with additional flow paths for oil, water and compressed air to emerge at the end of the most remote motion of the wrist unit.

One common expected use of the present invention would be as a supplementary attachment to an existing limited degree of freedom industrial manipulator.

It will be obvious to a skilled man that a machine can be further equipped with joint position instrumentation, and sensors for pressure and force and other parameter measurement. Such information can be passed back to a base station for closed loop and other forms of advanced control operation. Full computer control of the apparatus under full interactive control is thereby possible.

It is further apparent that in Fig. 1 structural connection to external apparatus can be made through the action of integral grippers - as in 15A or 15B - if such are provided, or alternatively through the action of an intermediate connection plate 16 if no integral gripper system is provided.

Claims (17)

1. An apparatus comprising: a first structural connection means, a first element attached to or formed integrally with said first structural connection means, a second element connected by connection means to said first element, said connection means providing at least one degree of freedom of movement of said second element relative to said first element, a second structural connection means attached to or formed integrally with said second element, a power inlet to said apparatus, remotely controllable actuation means operatively associated with said power inlet to affect or prevent movement of said second element relative to said first element, and functional element and circuitry means for modifying the control, mechanical and motion response and/or mechanical response and/or motion response of the actuation means during normal load driving, load driven and stress reversal situations.

2. The apparatus of claim 1 wherein said functional element and circuitry means provides positive locking of the element joints into position, such action being either automatically or discretionarily invocable or both.

3. The apparatus of claim 1 or claim 2 further comprising elements connected in series, by at least one degree of freedom powered motion joints, to said first and second elements.

4. The apparatus of claim 3 wherein four only elements are used and three orthogonally disposed pivotal motion axes are provided so as to generate an integrated wrist unit which provides motion in pitch, yaw and roll.

5. The apparatus of any one of the preceding claims wherein one or more of the actuator means comprise linear actuators operating through rack and pinion actuation systems optionally provided with anti-backlash control systems.

6. The apparatus of any one of the preceding claims further comprising remotely operable means for discretionary locking of one or more of the motion joints.

7. The apparatus of any one of the preceding claims wherein one or more of the elements are telescopic.

8. The apparatus of any one of the preceding claims further comprising a plain or controlled power outlet operatively associated with said power inlet for providing plain or controlled power to a device that might be attached to said structural connection means and wherein the controlled power outlet is coupled to remotely controllable power control means.

9. The apparatus of any one of the preceding claims further comprising link circuitry and/or duct means integrally with or through said first, second and any other elements to provide a means of power services and/or electric communication therethrough.

10. The apparatus of any one of the preceding claims wherein the power inlet is provided in single mode hydraulic, pneumatic or electrical form or in mixed or multiple input form.

11. The apparatus of any one of the preceding claims wherein power outlet means are provided in mixed hydrostatic, pneumatic or electrical power form.

12. The apparatus of any one of the preceding claims further comprising a centrally located open conduit through which a number of disparate utility service systems are removably accommodated.

13. The apparatus of any one of the preceding claims wherein said power inlet is provided by a singular pair of uncontrolled pressurised hydraulic fluid or pressurised pneumatic fluid supply and return lines.

14. The apparatus of any one of the preceding claims attached to and in combination with a limited degree of freedom industrial manipulator.

15. The apparatus of any one of the preceding claims wherein said first and second elements are pivotally interconnected by a pivot pin and mutually interconnected by a hydraulic ram to effect pivoting.

16. The apparatus of any one of the preceding claims wherein a rack and pinion system is employed at each connection.

17. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.