Artificial hands

• US 4,650,492 A
• Filed: 08/26/1985
• Issued: 03/17/1987
• Est. Priority Date: 08/24/1984
• Status: Expired due to Fees

• Current Assignee: J E Hanger & Company Limited
• Original Assignee: J E Hanger and Company Limited
• Inventors: Nightingale, James M., Barkhordar, Mohammad, May, Denis R. W.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Lastova, MaryAnn Stoll
• Application Number:
  US06/769,638
• Time in Patent Office: 568 Days
• Field of Search: 901/33-35, 901/31, 901/38, 901/39, 901/46, 901/47, 901/10, 128/77, 623/25, 623/63, 623/64, 623/24, 273/148 B, 250/231 P, 73/705
• US Class Current: 623/24
• CPC Class Codes: A61F 2/583 Hands; Wrist joints
• CPC Class Codes: A61F 2/586 Fingers
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61F 2002/587 Thumbs
• CPC Class Codes: B25J 13/083 fitted with slippage detectors
• CPC Class Codes: B25J 15/0009 comprising multi-articulated fingers, e.g. resembling a human hand

Abstract

An artificial hand comprises a palm member and thumb and finger members movable towards and away from one another by an actuator. A cosmesis covering the actuator has a touch sensor in a cavity of the cosmesis that deforms on contact with an object. The cavity is connected via a conduit with a microphone that picks up pressure waves resulting from stick/slip motion of the object along the surface of the cosmesis. The distance between the thumb and finger members is determined by a position sensor, and muscle sensor means responsive to contraction of first and second muscle groups supplies position and control signals in first and second channels. A controller operatively connected to the actuator is responsive to the presence and/or absence of signals in the first and second channels, the magnitudes of said channel signals when they are present, the presence and absence of contact signals from the touch sensor, the output of the position sensor, and the stick/slip signal from the microphone, to adjust the relative positions of the thumb and finger members.

Claims

1. An artificial hand comprising in combination:

a palm member, thumb and finger members supported by said palm member, and a cosmesis covering said palm, thumb and finger members;

an actuator operably connected to at least one of said thumb and finger members for moving said thumb and finger members towards one another to grip an object placed therebetween, and for moving said thumb and finger members away from one another to release said object;

touch sensor means operative to signal contact with said object, said touch sensor means consisting of at least one sensor which comprises an enclosed cavity defined by portions of said cosmesis, and a light source and a light detector within said cavity, portions of said cavity between said light source and said detector being deformable on contact with the object to provide said contact signal by reduction of the light that is transmitted between said light source and said detector;

a load slip sensor for sensing when the object gripped between said thumb and finger members slips, said load slip sensor comprising a microphone in said cosmesis, a conduit in said cosmesis connecting said microphone with said cavity, and detector means coupled to said microphone and selectively responsive to pressure waves resulting from stick/slip motion of said object along the surface of said cosmesis to provide a signal when the object slips;

muscle sensor means arranged to detect contraction of first and second muscle groups and to supply position and grip command signals through first and second control channels;

a position sensor arranged to signal change in distance between said thumb and finger members; and

control means for the actuator, said control means being (a) in a first state, in the absence of signals in the first and second control channels, where it responds to said position sensor to maintain a parked position of said thumb and finger members, (b) in a second state, in the presence of a signal in the first control channel and in the absence of a contact signal from said touch sensor means, where the actuator is caused to alter the spacing between said thumb and finger members in response to said signal in said first control channel, (c) in a third state, upon occurrence of a signal above a predetermined threshold in the second control channel and the presence of a contact signal from the touch sensor means, where a force exerted on said object by said actuator through said thumb and finger members is increased in response to the signal from said load slip sensor until the object no longer slips, and (d) in a fourth state, in response to a signal in the first channel above a predetermined threshold, where the actuator moves said thumb and finger members apart until said touch sensor means no longer gives a contact signal.

2. An artificial hand according to claim 1 wherein said muscle sensor means includes means responsive to contraction of the second muscle group resulting in a myoelectric current above a predetermined threshold to cause the control means to be altered from its second to its third states.

3. An artificial hand according to claim 2 wherein said muscle sensor means includes means responsive to contraction of the first muscle group resulting in a myoelectric current above a predetermined threshold to cause the control means to alter from its third to its fourth state.

4. An artificial hand according to claim 1, wherein the touch sensor means includes touch sensors on at least said thumb member and said finger member of said hand.

5. An artificial hand according to claim 1, wherein the position sensor is a Hall effect encoder on the shaft of a motor of the actuator connected to up/down counter means that stores the distance between the thumb and finger members.

6. An artificial hand according to claim 1, wherein the light source is a light (including infra red) emitting diode and the light detector is a phototransistor.

7. An artificial hand according to claim 1, wherein said cavity is gas-tight and a second conduit leads to pressure sensor means operative to give a signal in response to the pressure in said cavity.