GB1578340A - Mechanical hands eg for diving apparatus - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATIN G TO MECHANICAL HANDS, E.G.

FOR DIVING APPARATUS (71) We, NORMALAIR-GARRETT (HOLD INGS) LIMITED, of Westland Works, Yeovil, in the County of Somerset, a British Com- pany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to mechanical hands, and is particularly concerned with mechanical hands for use with deep diving suits.

One problem with mechanical hands, particularly when used with diving suits or other diving enclosures, is that in general they resemble claws or pipe grips and are located remote from the operating hands of the user, for example a diver. In consequence the user may experience difficulty in accurately locating the mechanical hand with an object to be handled, since he is devoid of normal co-ordination between hand and eye. Moreover, the user has no sense of feel when the mechanical hand is grasping an object.

An object of the present invention is to provide a mechanical hand in which the hand of the user is located within the mechanical hand, and gripping members of the mechanical hand function in close positional relationship and operating manner to the fingers and thumb of the hand of a user, so that the action of locating and handling an object becomes an instinctive action that is similar to the normal coordination between hand and eye.

Another object of the present invention is to provide a mechanical hand in which pressure exerted by gripping members of the hand is related to the pressure exerted by the user, so that the user retains a sense of feel throughout a gripping operation.

According to the present invention a mechanical hand comprises a rigid hand enclosure for housing the hand of a user, a thumb gripping element and a fingers gripping element extending from the hand enclosure, one of said gripping elements being pivotally attached to the hand enclosure so as to be capable of movement towards and away from the other gripping element, and an hydraulic actuator arrangement for operating said movable element, said arrangement including fluid pressure control means responsive to a manually movable member housed within the hand enclosure and arranged to translate a force applied by a user to the manually movable member into rapid movement of said movable gripping element when the latter is unconstrained, and into a related force applied through said movable gripping element to exert a firm grip on an object grasped by said elements and constraining movement of the movable element, whereby the user maintains a sense of feel while operating the mechanical hand to handle an object.

Preferably, the thumb gripping element is fixed and provides accommodation for the thumb of a user, and is complementary to the fingers gripping element which is pivotally attached to the hand enclosure.

With this arrangement, the thumb gripping element serves as a positional datum so that near normal co-ordination between eye and hand is possible, thereby allowing the location and handling of an object to be made in an instinctive manner.

The fingers gripping element may be arranged so that various finger tips can be selectively fitted for co-operating with the thumb gripping element, whilst similarly, various interchangeable thumb tips may also be selectively fitted, whereby objects can be gripped between gripping elements that offer the most suitable profile thereto.

However, the fingers and thumb gripping elements may be, themselves, co-operably profiled.

To facilitate accomplishment of rotary movements such as are used in screwing operations, e.g. with nuts on studs and with bolts in blind holes, the mechanical hand may be provided with a secondary thumb gripping element and a secondary fingers gripping element arranged to be on opposite sides of the longitudinal axis of the forearm of a user.

The manually movable member is preferably arranged so that the four fingers of the hand of a user fold around it, whereby a grip may be obtained between the thumb accommodation and the movable member.

A gripping or squeezing action of the hand of a user, for either increasing or decreasing pressure, is thus translated into movement of the movable gripping element by the movable member within the hand enclosure being moved towards or away from the thumb of the user.

In a preferred embodiment of the invention, movement of the manually movable member operates a hydraulic actuator arrangement including a hydraulic actuator having a piston connected to said movable gripping element, a first operating piston of larger cross-sectional area than said hydraulic actuator piston and a second operating piston of smaller cross-section area than said hydraulic actuator piston.The first and second operating pistons are arranged to be loaded by the manually movable member, when moved by the user, the arrangement being such that when the movable gripping element is unconstrained, movement of the manually movable member moves the first operating piston to produce rapid movement of the movable grip ping hydraulic actuator and hence of the movable gripping element, whereas when the movable gripping element is constrained by engagement with an object grasped by the gripping elements, movement of the manually movable member moves said second operating piston to increase fluid pressure acting on the actuator piston so as to increase the grip exerted on the object grasped by the gripping elements.

The invention will be more readily understood from the following description of an exemplary embodiment with reference to the accompanying drawings in which: - Figure 1 illustrates a cross-sectional view of a mechanical hand according to the invention; Figure 2 is a fragmentary section of Figure 1 on line A-A; Figures 3, 4 and 5 illustrates, schematically, three phases of operation of the hydraulic arrangement in actuating the finger means; Figure 6 illustrates an optional addition to the hand shown in Figure 1; and Figure 7 illustrates a diving suit incorporating the invention.

A mechanical hand 10 in accordance with the invention, and shown in Figures 1 and 2, comprises a rigid hand enclosure member 11 that is attached to the lower arm section 12 of a deep diving suit, shown in Figure 7, by means of an articulated wrist joint 13. As shown in Figures 1 and 2, the hand enclosure member 11 has a rigid thumb gripping element 14 extending therefrom and into which the thumb of the diver is inserted, whilst a fingers gripping element 15 is pivotally attached to the outside of the hand enclosure member 11 so as to be arcuately movable about a pair of pivots 16 towards and away from the thumb gripping element 14 by means of a manually operated hydraulic actuator arrangement contained in the hand enclosure member 11.Accommodation for the thumb of the diver is insulated and sufficiently large to allow the thumb to be withdrawn for exercise with the fingers in order to combat the possible onset of cramp.

The hydraulic actuator arrangement comprises a small hydraulic actuator 17 housed in the back of the hand enclosure member 11 and arranged to operate against a compression spring 18 with a roller 19 of a cross-member 20 interposed between them.

The cross-member 20 is pinned to the pivots 16 as is the fingers gripping element 15.

The pivots 16 pass through and are borne in the side walls of the hand enclosure member 11, being each sealed by a pair of seals 21. A manually movable member 22 is provided within the hand enclosure member 11 in a position convenient for the fingers of the diver to close on, and is supported with pivotal freedom at its ends by first and second operating pistons 23, 24 (see Figure 3), extending from respective first and second cylinders 25 26 (see Figure 3). As is shown in Figure 3, the cylinder 25 contains a valved piston head 27 enclosing a valve head 28 provided at that end of the piston 23 remote from the manually movable member 22. The valve head 28 is normally held off a co-operable seat 29 in the valved piston head 27 by a compression spring 30 reacting between the cylinder 25 and a collar on the piston 23.

The end of the cylinder 25 remote from the member 22 is connected with the hydraulic actuator 17 by way of a non-return valve 31 and a duct 32. Another duct 33 extends from a port on the side of the cylinder 25 to conjoin with the duct 32.

The valved piston head 27 always straddles the port connecting the duct 33 to the cylinder 25 and, being waisted between its ends, provides via ports 34 communication between the duct 33 and a central chamber 35 for which the valve seat 29 describes an outlet to the non-return valve 31. This arrangement results in there being no net thrust upon the piston head 27 from pressure in the duct 33 when the valve head 28 is closed upon the valve seat 29: that is, the piston head 27 is pressure-balanced with respect to the pressure in the duct 33. The second operating piston 24 is of small diameter relative to the valved piston head 27, and its cylinder is connected to the hydraulic actuator 17 by way of a duct 36 conjoined with the ducts 32, 33.

Figure 3 illustrates the arrangement in a released condition, ready to be operated by the fingers of a diver moving the manually movable member 22 to cause the pistons 23, 24 to be pushed into their cylinders, so as to cause hydraulic fluid to flow towards the hydraulic actuator 17 both by direct action of the small piston 24 and by indirect action of the piston 23 which closes onto the valve seat 29 within the valved head.For so long as there is negligible piston head 27 before moving that piston resistance to movement of the actuator 17 in response to fluid flow into the duct 32, both pistons 23 and 24 can move to displace a large volume of fluid into the duct 32 to cause a rapid movement of the latter to move the fingers gripping element 15 towards the thumb gripping element 14; however, when the fingers gripping element 15 contacts an object to be held, the increase in fluid pressure in the duct 32 as movement of the actuator 17 is opposed acts to arrest movement of the valved piston head 27 as a consequence of this having a larger area than both the piston of the actuator 17 and the piston 24.As illustrated in Figure 4, the piston 24, being of smaller area than the piston of the hydraulic actuator 17, is able to continue its movement and build up pressure in the hydraulic actuator 17 to drive the fingers gripping element 15 to increase its grip on the object. The continuing movement of the small piston 24 and the concomitant increase in fluid pressure in the duct 32 has no effect on the valved piston head 27 because the non-return valve 31 prevents return flow of fluid into the end of the cylinder 25 while the rising pressure in the central chamber 35, by way of duct 33, is ineffective, owing to the described pressurebalancing arrangement of the valved piston head.

Upon release of the member 22, the compression spring 30 expands as illustrated in Figure 5 to lift the valve-head 28 off the valve seat 29 of the valved piston head 27, permitting fluid to flow into the cylinder 25 through the duct 33, the chamber 35 and the port controlled by the valve head 28 and the seat 29. This flow is induced by the spring 18 driving the piston of the hydraulic actuator 17 towards its released position, and causes also the return of the piston 23 and 24, and of the piston head 27 and of the member 22, to their initial, released, positions.

An optional addition to the mechanical hand 10 that facilitates a screwing action by the user is shown in Figure 6. A secondary thumb gripping element 40 is secured on the hand enclosure member 11 remote from the wrist so as to project axially thereof, and a secondary fingers gripping element 41 is carried from a modified attachment yoke 42 that also carries the principal fingers gripping element 15 and is rotatable about the pivots 16. To assist in obtaining a good gripping position the secondary fingers gripping element 41 is pivotally attached to the yoke 42 so as to allow a limited angular adjustment relative to the gripping face of the secondary gripping element 40.The two secondary gripping elements 40, 41, are so arranged that when an object, such as a bolt, that is to be rotated, is being gripped, the axis of rotation is substantially aligned with the longitudinal axis of a forearm of the user.

The two fingers gripping elements 15, 41, move in unison during operation, the action of one of one fingers element being redundant, according to the job being done.

It will be appreciated that various modifications and alternatives may be made without departing from the scope of the invention; for example, whereas in the embodiment of the invention described with reference to and shown in the accompanying drawings, the thumb gripping element is used as the positional datum in the location of an object, the fingers gripping element may alternatively be so used, in which case the fingers gripping element is fixed and the thumb element pivotally attached to the hand enclosure member and moved hydraulically.

Moreover, whilst only simple finger means and thumb element have been described, a non-illustrated modification provides a mechanical hand with means for fitting fingers and thumb tip gripping elements of various forms and profiles to suit particular gripping or holding requirements of the hand.

WHAT WE CLAIM IS: 1. A mechanical hand comprising a rigid hand enclosure for housing the hand of a user, a thumb gripping element and a fingers gripping element extending from the hand enclosure, one of said gripping elements being pivotally attached to the hand enclosure so as to be capable of move ment towards and away from the other gripping element, and an hydraulic actuator arrangement for operating said movable element, said arrangement including fluid pressure control means responsive to a manually movable member housed within

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. is closed upon the valve seat 29: that is, the piston head 27 is pressure-balanced with respect to the pressure in the duct 33. The second operating piston 24 is of small diameter relative to the valved piston head 27, and its cylinder is connected to the hydraulic actuator 17 by way of a duct 36 conjoined with the ducts 32, 33. Figure 3 illustrates the arrangement in a released condition, ready to be operated by the fingers of a diver moving the manually movable member 22 to cause the pistons 23, 24 to be pushed into their cylinders, so as to cause hydraulic fluid to flow towards the hydraulic actuator 17 both by direct action of the small piston 24 and by indirect action of the piston 23 which closes onto the valve seat 29 within the valved head.For so long as there is negligible piston head 27 before moving that piston resistance to movement of the actuator 17 in response to fluid flow into the duct 32, both pistons 23 and 24 can move to displace a large volume of fluid into the duct 32 to cause a rapid movement of the latter to move the fingers gripping element 15 towards the thumb gripping element 14; however, when the fingers gripping element 15 contacts an object to be held, the increase in fluid pressure in the duct 32 as movement of the actuator 17 is opposed acts to arrest movement of the valved piston head 27 as a consequence of this having a larger area than both the piston of the actuator 17 and the piston 24.As illustrated in Figure 4, the piston 24, being of smaller area than the piston of the hydraulic actuator 17, is able to continue its movement and build up pressure in the hydraulic actuator 17 to drive the fingers gripping element 15 to increase its grip on the object. The continuing movement of the small piston 24 and the concomitant increase in fluid pressure in the duct 32 has no effect on the valved piston head 27 because the non-return valve 31 prevents return flow of fluid into the end of the cylinder 25 while the rising pressure in the central chamber 35, by way of duct 33, is ineffective, owing to the described pressurebalancing arrangement of the valved piston head. Upon release of the member 22, the compression spring 30 expands as illustrated in Figure 5 to lift the valve-head 28 off the valve seat 29 of the valved piston head 27, permitting fluid to flow into the cylinder 25 through the duct 33, the chamber 35 and the port controlled by the valve head 28 and the seat 29. This flow is induced by the spring 18 driving the piston of the hydraulic actuator 17 towards its released position, and causes also the return of the piston 23 and 24, and of the piston head 27 and of the member 22, to their initial, released, positions. An optional addition to the mechanical hand 10 that facilitates a screwing action by the user is shown in Figure 6. A secondary thumb gripping element 40 is secured on the hand enclosure member 11 remote from the wrist so as to project axially thereof, and a secondary fingers gripping element 41 is carried from a modified attachment yoke 42 that also carries the principal fingers gripping element 15 and is rotatable about the pivots 16. To assist in obtaining a good gripping position the secondary fingers gripping element 41 is pivotally attached to the yoke 42 so as to allow a limited angular adjustment relative to the gripping face of the secondary gripping element 40.The two secondary gripping elements 40, 41, are so arranged that when an object, such as a bolt, that is to be rotated, is being gripped, the axis of rotation is substantially aligned with the longitudinal axis of a forearm of the user. The two fingers gripping elements 15, 41, move in unison during operation, the action of one of one fingers element being redundant, according to the job being done. It will be appreciated that various modifications and alternatives may be made without departing from the scope of the invention; for example, whereas in the embodiment of the invention described with reference to and shown in the accompanying drawings, the thumb gripping element is used as the positional datum in the location of an object, the fingers gripping element may alternatively be so used, in which case the fingers gripping element is fixed and the thumb element pivotally attached to the hand enclosure member and moved hydraulically. Moreover, whilst only simple finger means and thumb element have been described, a non-illustrated modification provides a mechanical hand with means for fitting fingers and thumb tip gripping elements of various forms and profiles to suit particular gripping or holding requirements of the hand. WHAT WE CLAIM IS:

1. A mechanical hand comprising a rigid hand enclosure for housing the hand of a user, a thumb gripping element and a fingers gripping element extending from the hand enclosure, one of said gripping elements being pivotally attached to the hand enclosure so as to be capable of move ment towards and away from the other gripping element, and an hydraulic actuator arrangement for operating said movable element, said arrangement including fluid pressure control means responsive to a manually movable member housed within

the hand enclosure and arranged to translate a force applied by a user to the manually movable member into rapid movement of said movable gripping element when the latter is unconstrained, and into a related force applied through said movable gripping element to exert a firm grip on an object grasped by said elements and constraining movement of the movable element, whereby the user maintains a sense of feel while operating the mechanical hand to handle an object.

2. A mechanical hand as claimed in Claim 1, wherein the hydraulic actuator arrangement includes a hydraulic actuator having a piston connected to said movable gripping element, a first operating piston of larger cross-sectional area than said hydraulic actuator piston and a second operating piston of smaller cross-sectional area than said hydraulic actuator piston, said first and second operating pistons being arranged to be loaded by said manually movable member so as to exert fluid pressure on said hydraulic actuator piston, the arrangement being such that when the movable gripping element is unconstrained, movement of said manually movable member moves said first operating piston to produce rapid movement of the hydraulic actuator and hence of the movable gripping element, whereas when the movable gripping element is constrained by engagement with an object grasped by the gripping elements, movement of the manually movable member moves said second operating piston to increase fluid pressure acting on said hydraulic actuator piston so as to increase the grip exerted on the object grasped by said gripping elements.

3. A mechanical hand as claimed in Claim 2, wherein said first operating piston has a valve head co-operable with a valve seat in a valved piston head movable in a cylinder having its end remote from said manually movable member connected with said hydraulic actuator by way of a nonreturn valve, the cylinder having a further connection with said hydraulic actuator by way of a port straddled by said valved piston head and with respect to which the valved piston head is pressure-balanced, said valve head and valve seat providing a flow path between said port and said remote end of the cylinder when said first piston is free of load from said manually movable member.

4. A mechanical hand as claimed in any one of the preceding Claims, wherein the thumb gripping element is fixed and the fingers gripping element is pivotally attached to the rigid hand enclosure.

5. A mechanical hand as claimed in Claim 4, wherein the thumb gripping element provides accommodation for the thumb of a user.

6. A mechanical hand as claimed in any one of the preceding Claims, including secondary thumb and fingers gripping elements on the rigid hand enclosure and arranged to be on opposite sides of the longitudinal axis of the forearm of a user.

7. A mechanical hand as claimed in Claim 6, wherein the secondary fingers gripping element is movable and the secondary thumb gripping element is fixed.

8. A mechanical hand as claimed in any one of the preceding Claims in combination with a diving suit.

9. A mechanical hand substantially as hereinbefore described with reference to and as shown in Figures 1 to 5 of the accompanying drawings.

10. A mechanical hand as claimed in Claim 9 having secondary thumb and fingers gripping elements substantially as hereinbefore described with reference to and as shown in Figure 6 of the accompanying drawings.

11. A mechanical land as claimed in Claim 9 or Claim 10 in combination with a deep diving suit substantially as hereinbefore described with reference to and as shown in Figure 7 of the accompanying drawings.