US3620095A

US3620095A - Mechanically actuated triggered hand

Info

Publication number: US3620095A
Application number: US69209A
Authority: US
Inventors: Dan H Dane
Original assignee: National Aeronautics and Space Administration NASA
Current assignee: National Aeronautics and Space Administration NASA
Priority date: 1970-09-03
Filing date: 1970-09-03
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

A MECHANICALLY ACTUATED HAND THAT CAN GRASP ON OBJECT LIKE A TRIGGER ACTUATED TOOL AND DEPRESS THE TRIGGER OF THE TOOL. THE HAND INCLUDES A SUPPORTING FRAME, A PAIR OF JAW MEMBERS SLIDABLY MOUNTED ON THE FRAME AND A DRIVE ASSEMBLY SLIDABLY MOUNTED ON THE FRAME AND MECHANICALLY COUPLED TO THE JAW MEMBERS FOR PERMITTING MOVEMENT THEREOF ALONG THE FRAME. A TRIGGER DEVICE MOUNTED IN EACH JAW MEMBER IS CONNECTED BY A MECHANICAL LINKAGE TO THE DRIVE ASSEMBLY SO AS TO BE ACTUATED THEREBY. A BRAKE MECHANISM IS MOUNTED ON THE FRAME ADJACENT EACH JAW MEMBER FOR SELECTIVELY IMMOBILIZING THE JAW MEMBERS. A TOUCH CONTROL DEVICE MOUNTED IN EACH JAW MEMBER IS ACTUATED BY A PREDETERMINED CONTACT FORCE WITH AN OBJECT BEING GRASPED AND THE TOUCH CONTROL IN TURN ACTUATES THE BRAKE MECHANISM TO IMMOBILIZE THE JAW MEMBER RELATIVE TO THE FRAME.

Description

Nov. 16, 1971 D. H. DANE MECHANICALLY ACTUATED TRIGGERED HAND 3 Sheets-Shoot 1 Filed Sept. 5, 1970 FIG.2

DAN H. DANE INVENTOR ATTORNEY Nov. 16, 1971 D, 'H, DANE 3,620,095

Filed Sept. 5, 1970 3 Sheets-Shoot 5 KO 2 L) DAN H. DANE INVENTOR ,BY Mad/6% ATTORNEY United States Patent Int. Cl. A61f 1/06 US. Cl. 74-469 7 Claims ABSTRACT on THE DISCLOSURE A mechanically actuated hand that can grasp an object like a trigger actuated tool and depress the trigger of the tool. The hand includes a supporting frame, a pair of jaw' members slidably mounted on the frame and a drive as'sembly slidably mounted on the frame and mechanically coupled to the jaw members for permitting movement thereof along the frame. A trigger device mounted in each jaw member is connected by a mechanical linkage to the drive assembly so as to be actuated thereby. A brake mechanism is mounted on the frame adjacent each jaw member for selectively immobilizing the jaw members. A touch control device mounted in each jaw membe} is actuated by a predetermined contact force with an object being grasped and the touch control in turn actuates the brake mechanism to immobilize the jaw member relative to the frame.

ORIGIN OF THE INVENTION The invention described herein was made by an employee of the US. Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Field of the invention The invention relates in general to mechanical hands for mounting'on some type of manipulator arm or boom. More particularly, the invention relates to mechanical hands which can in addition to grasping an object like a tool, also manipulate some portion of the tool like, for example, the trigger thereof.

Discussion of prior art is an inherent disadvantage of mechanical hands and the problem is compounded by the customary mounting of the mechanical hand on a manipulator arm having two or more pivotal sections.

SUMMARY OF THE INVENTION The present invention avoids the above mentioned disadvantages at least to some extent. Assume that the tool to be manipulated is an impact tool for applying an impact load to a workpiece; such a tool must be grasped and then the trigger thereof depressed to actuate the tool. The present invention accomplishes this by mounting a triggering device in each of two jaw members which hold the tool. The triggering device is actuated after the tool is grasped.

The hand includes a supporting frame on which the two grasping jaws are slidably mounted. A motorized drive assembly is slidably mounted on the frame and this 3,620,095 Patented Nov. 16, 1971 assembly is connected to a pivotal linkage mounted in each jaw member. This linkage is also connected to the triggering device in each jaw member so that in addition to opening the jaw members it will actuate the triggering device in each jaw member. The jaw members are closed by a spring and cable assembly connected between the carriage and each jaw member.

Each of the jaw members have a touch control device mounted therein that is electrically connected to a brake mechanism mounted on the frame. The purpose of the brake mechanism is to immobilize the jaw members and there are two brake mechanisms, one for each jaw member. The touch control devices are actuated by contact with an object being grasped and each one actuates a brake mechanism to immobilize a jaw member. With one jaw member immobilized the other jaw member will continue to move until it engages the object being grasped. Control means in the form of limit switches and the like are included in the hand to control the operation thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial view showing the hand grasping an impact tool;

FIG. 2 is a side view of the hand with certain components removed for clarity of illustrations;

FIG. 3 is a top view of the hand, that is looking down on the hand as shown in FIG. 1, with portions thereof removed to illustrate the linkage that moves the jaw members out and actuates the triggering links;

FIG. 4 is a bottom view of the hand showing the underside thereof as positioned in FIG. 1;

FIG. 5 is a cross sectional side view of the hand taken along lines 5-5 of FIG. 3;

FIG. 6 is a schematic illustration of the hand positioned for grasping a small lightweight object;

FIG. 7 shows the hand after the jaw members have been moved so that one jaw is in contact with the object being grasped;

FIG. 8 shows the hand grasping the object with both jaw members.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1 a mechanical hand 10 is shown grasping an impact tool 12. The hand has two

moveable jaw members

14 and 16 and in FIG. 1 these jaw members are closed on handle 18 of the impact tool. A trigger 20 is mounted in handle 18 of the tool for actuating the tool. Trigger 20 is depressed by triggering

links

22 and 24 mounted in the jaw members.

In FIG. 2 the hand is illustrated with several parts of the hand removed in an attempt to clarify the construction of the hand. The jaw members are slidably mounted on a downwardly extending flange 26 on one end of frame member 28. A motor drive assembly 30 is mounted on the rearward end of the frame 28. The drive assembly includes an electric motor and suitable gear reduction mechanism for driving a threaded shaft 32 (see FIG. 3) at a desired rate. The frame member has a horseshoe like shape and the drive assembly is positioned in the approximate center thereof. A linkage mechanism 34, connected between threaded screw 32 and

jaw members

14 and 16, is shown in FIG. 3 and to some extent in FIGS. 4 and 5. The details and operation of the linkage will be discussed hereafter. Linkage mechanism 34 is not shown in FIG. 2.

The jaw members have Teflon blocks 36 and 38 (see FIGS. 4 and 5) mounted to the undersides thereof and these Teflon blocks slide in a guideway 40 formed by flange 26 of frame 28 and crossbeam 42. Crossbeam 42 is maintained in a spaced position relative to flange 26 by

spacer blocks

44 and 46, secured in place at each end of crossbeam 42 by through

bolts

48 and 50, and by a tubular spacer 51 secured by a bolt 53 (see FIG. The through bolts screw into threaded openings (not shown) in flange 26. Flange 26 and crossbeam 42 are provided with concave grooves 52 and 54 that form the guideway in which the Teflon blocks slide. The Teflon blocks have convex surfaces thereon that exactly fit grooves 52 and 54.

A pair of coil springs 56 and 58 (see FIG. 3) are mounted on frame 28. The two springs apply a force to the jaw members that tends to slide the jaw members together. Spring 56 is anchored at one end to frame 28 by a screw 60 and the other end thereof is connected to a cable 62. Cable 62 passes over a pulley 64 (see FIGS. 1 and 2) and fastens to jaw member 16. The length of the cable and the arrangement of spring 56 is such that outward movement of jaw member 16 by the drive assembly and linkage, described in detail hereafter, will expand spring 56. Thus, if not restrained, jaw member 16 will slide inward due to the action of spring 56. Spring 58 is connected to a cable 66 that is similarly arranged over a pulley (not shown) and connected to jaw member 14 so as to tend to pull jaw member 14 inwardly.

The motor drive assembly 30 includes an electric motor that drives a gear reduction mechanism which in turn drives threaded screw 32 at a desired rate of rotation. For the hand illustrated this rate is 120 revolutions per minute, however this rate would be varied for different hand sizes. The rearward side of drive assembly 30 has a mounting lug 68 formed thereon. The lug has a through hole in which a Teflon bushing 70 is mounted. Bushing 70 slides over a polished shaft 71 which is supported at each of its ends in mounting

lugs

72 and 74 that are an integral part of frame 28. The lugs are provided with

set screws

76 and 78 to secure shaft 72 in place. The forward end of the drive assembly is provided with a projecting portion 80 that has a through hole which accommodates a polished shaft 82 supported by mounting lugs 84 and 86 are bolted to frame 28 by

bolts

85 and 87. Shaft 82 86. Lugs 84 and 86 are bolted to frame 28 by

bolts

85 and 87. Shaft 82 is secured in its mounting lugs by set screws. The through hole in projecting portion 80 is provided with a Teflon bushing 83. As is probably apparent, housing 30 is slideable on

shafts

71 and 82 relative to frame 28 and the reason for this will become apparent as the description of the invention progresses.

A collar 79 that has a threaded hole formed therein is mounted on threaded screw 32 so that rotation of screw 32 will result in movement of collar 79 along the length thereof. Forward movement of collar 79 is limited by stop 91 mounted on frame 28. A first pair of links 88 and 89 are pivotally mounted at one of their ends to collar 79 by pins 90 and 92. The other ends of links 88 and 89 are pivotally connected by pins 93 and 95 to the ends of a pair of intermediate links 94 and 96. The two intermediate links are pivotally mounted on their respective jaw members at a point intermediate the ends thereof by pins 98 and 100. The intermediate links are in turn each pivotally connected to an end of one of a pair of end links 102 and 104. The other ends of links 102 and 104 are pivotally connected to triggering

links

22 and 24. As shown in FIG. 3, triggering link 22 is pivotally connected to jaw member 14 by a pin 106 and to end link 102 by pin 108. Triggering link 24 is similarly connected to jaw member .16 and end link 104 by pins and 107.

When the linkage is in the position shown in FIG. 3 clockwise rotation of screw 32 will move collar 79 toward motor drive assembly 30. This will cause that part of the linkage connected by pins 93 and 95 to move inwardly resulting in two possible motions of the linkage. If the two jaw members have not moved against an object to be grasped then the jaw members will move toward one another under the action of

springs

56 and 58 as links 88 and 89 move rearwardly towards the motor drive assembly. As soon as the jaw members contact an object such as the handle of impact tool 12 the jaw members are no longer free to move inwardly and continued rearward movement of links 88 and 89 will result in pivotal movement of intermediate links 94 and 96 about the pinned connection made by pins 98 and 100. Such movement will cause, as is apparent from the consideration of FIG. 3, forward movement of end links 102 and .104 so as to pivot triggering

links

22 and 24 outwardly out of the jaw members into a position like that shown in FIG. 1 where the triggering links will engage the trigger of impact tool 12. In FIG. 3, the position of intermediate link 96 and link 104, when intermediate link 96 has been pivoted about pin 100, is shown in dotted lines. In FIG. 3, it can be seen how forward movement of end link 102 will move pin 108 relative to pin 106 causing triggering link 22 to rotate about pin 106. The connection between triggering link 24 and end link 104 is identical to that of triggering link 22 and end link 102. The pivoted position of link 24 is shown in dotted lines.

The jaw members are each provided with a touch control system that includes switches 110 and .112 mounted in the forward end of each jaw member. Switches 110 and 112 are suitable electrical switches actuated upon contact with an object positioned between the jaw members. The switches are electrically connected to solenoid

brake devices

114 and 116 mounted on frame 28; which function to immobilize the jaw members. Solenoid brake mechanism 114 includes (see FIG. 4) an axially moveable plunger 118 fastened to a lever 120 that is pivotally mounted to frame 28 by means of a pin 122. A spring 124 is mounted around shaft 118 so as to normally bias lever 120 away from the jaw members. Jaw member 14 has an L-shaped plate 126 mounted thereto that includes a surface 128 (see FIG. 5) against which lever 120 bears. Lever 120 of the brake mechanism is provided with a friction type surface 130 which engages surface 128 when the solenoid brake mechanism is actuated. When the solenoid is actuated plunger 118 is pulled to the rear and this pivots lever 120 about pin 122 causing surface 130 to impinge against surface 128 and results in jaw member 14 being immobilized. Brake mechanism 116 functions in an identical manner to immobilize jaw member 16. The touch control system is intended for use in applications where small or lightweight objects are to be picked up so as to prevent toppling of the small object to be grasped. The touch control will not be needed when large objects like tool 12 are to be grasped.

Each jaw member has a limit switch mounted therein that is engaged by the linkage, described above, during some stage in the operation of the hand. Limit switch 130' in jaw member 14 is contacted by one end of intermediate link 94 when the linkage mechanism is in the position shown in FIG. 3. When the linkage has moved to the position shown partially in phantom in FIG. 3 then limit switch 130' is no longer engaged by intermediate link 94 and limit switch 132 is contacted by intermediate link 96 so as to actuate limit switch 132.

Two modes of operation of the invention will now be discussed; the grasping of a small lightweight object and the grasping and triggering of a tool like the impact tool 12 shown in FIG. 1. In grasping a lightweight object, assuming that frame 28 is connected to a suitable manipulator arm and the jaws of the hand are open as shown in FIG. 6, the hand is positioned adjacent an object such as a small container 136 that is to be grasped. The hand would be moved to a position where container 136 would be positioned between the jaws. The motor drive assembly would then be actuated to begin rotation of threaded screw 32 which in turn pulls collar 79 towards the motor drive assembly.

Jaws

14 and 16 would thus be permitted to slide inwardly under the actions of

springs

56 and 58 until, as illustrated in FIG. 7, jaw 14 engages container 136 and touch control device 110 is actuated by this contact. Actuation of switch 110 of the touch control system activates solenoid 114 so as to immobilize jaw 14 relative to frame 28. However, the drive motor assembly continues to run and threaded screw 32 turns and collar 79 continues to travel rearwardly. Considering the fact that frame 28 is held stationary by the manipulator arm upon which it is mounted, and jaw member 14 is held stationary relative to frame 28 by brake mechanism 114, it is apparent that something must slide if the collar 79 and links 88 and 89 continue to move rearwardly. law 16 is still free to slide and this will permit inward movement of link 89, but in order for link 88 to move rearwardly it is necessary that either jaw member 14 be able to slide or for drive assembly 30 to move to the left as viewed in FIG. 7. In order for the jaws to grasp object 136 as illustrated in FIG. 8, it is necessary that housing 30 slide to the left before jaw member 16 can close on object 136. Movement of the drive motor assembly is, as previously described, made possible by slidably mounting the motor drive assembly on

shafts

71 and 82. By providing the jaw members with a sensitive touch control system delicate objects can be grasped without injury or toppling.

Another mode of operation is where the hand is used to grasp a tool as illustrated in FIG. 1 of the drawings. Here the object is to grasp the handle of the tool and thereafter actuate the trigger so as to operate the tool. This is accomplished by first positioning the jaws of the hand around the handle of the tool in a manner illustrated in phantom lines in FIG. 3. The motor drive assembly is then actuated to move collar 79 rearwardly and permit the jaws to close upon the handle of the tool. The grasping force of the jaws is controlled by the amount of spring tension in

springs

56 and 58. The linkage connected between collar 79 and the jaws does not apply a positive inward force on the jaw members, but only permits the jaw members to come together under the action of their respective spring and cable assemblies. When further inward motion of the jaw members is stopped because of an object placed therebetween, then continued rearward movement of collar 79 will cause rotation of intermediate links 94 and 96 which in turn results in motions of links 102, 104 and trigger

links

22 and 24. Rotation of intermediate link 94 will result in link 94 becoming disengaged from limit switch 130 stopping the operation of the drive motor assembly. This of course only occurs after both jaws have moved against the object to be grasped. Thereafter, actuation of the drive motor assembly so as to continue the rearward movement of collar 79 on threaded screw 32 will cause the linkage to pivot about its various points causing triggering

links

22 and 24 to impinge upon the object being grasped. When the linkage has pivoted as far as possible then intermediate link 96 engages limit switch 132, as illustrated in phantom lines, and again stops the operation of the drive motor assembly.

The circuitry involved in controlling the operation of a hand like that disclosed herein can either be very sophisticated or quite simple depending upon the nature of the use to which the hand is to be put. For this reason the circuitry has not been disclosed in detail because designing and fabrication of a suitable circuit for a particular application of the hand could be readily accomplished by one skilled in that art.

What is claimed is:

1. A mechanically actuated triggered hand for grasping and activating a device comprising:

a frame upon which the parts of the hand are mounted,

a first jaw member slidably mounted on said frame,

a second jaw member slidably mounted on said frame adjacent said first jaw member,

triggering means mounted in said jaw members for exerting a force on the object being grasped, and drive means slidably mounted on said frame and operatively connected to said first and second jaw members and said triggering means, said drive means operating to slide either or both of said first and second jaw members along said frame to a grasping position and to actuate said triggering means.

2. The triggered hand recited in claim 1 which further includes:

a pair of brake mechanisms mounted on said frame for engagement with said jaw members, one of said brake mechanisms immobilizing said first jaw member and the other brake member immobilizing said second jaw member, and

a touch control means mounted on said jaw members and connected to said brake mechanism for actuation of the brake mechanisms.

3. The triggered hand recited in claim 2 wherein said touch control means includes,

a sensing element is mounted in each jaw member so as to contact an object being grasped, said element being connected to said brake mechanism for selectively actuating one of said brake mechanisms when a predetermined force is exerted on said touch control means by engagement thereof with an object being grasped.

4. The triggered hand recited in claim 3 wherein:

a crossbeam is mounted on one end of the frame to provide a guideway in which the first and second jaw members can slide,

said first and second jaw members each having a block member mounted thereon that is positioned in said guideway for supporting said first and second jaw members for slidable movement relative to said frame and each other.

5. The triggered hand recited in claim 4 wherein said triggering means includes:

a pair of links pivotally mounted in said first and second jaw members, a single link being mounted in each jaw member in a position such that the links are in opposing relation and bear against an object being grasped by said jaw members, and

linkage means pivotally mounted on said first and second jaw means and connected to said pair of links and to said drive means for actuating said pair of links.

6. The triggered hand recited in claim 5 wherein:

said drive means includes a motor slidably mounted on said frame that has a threaded shaft extending therefrom and rotated thereby, and

said linkage means includes an internally threaded coupling mounted on said threaded shaft whereby rotation of said shaft by said motor will result in motion of the internally threaded coupling which in turn will actuate said linkage means to move said jaw members and said trigger means.

7. The triggered hand recited in claim 6 which further includes:

spring means mounted on said carriage and connected to said jaw members so as to tend to move said jaw members away from each other, said spring means being expanded by movement of said jaw members away from one another by said drive means.

References Cited UNITED STATES PATENTS 3,171,549 3/1965 Orlolf 294-106 EVON C. BLUNK, Primary Examiner I. K. SILVERMAN, Assistant Examiner US. Cl. X.R.

3-l2; 2l4-l CM; 294-111, 113,