Robotic gripper having strain sensors formed on a semiconductor substrate

• US 5,092,645 A
• Filed: 06/19/1989
• Issued: 03/03/1992
• Est. Priority Date: 09/18/1987
• Status: Expired due to Fees

• Current Assignee: Wacoh Company
• Original Assignee: Wacoh Company
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Spar, Robert J.
• Assistant Examiner(s): Eller, J.
• Application Number:
  US07/362,399
• Time in Patent Office: 988 Days
• Field of Search: 414/730, 901/32, 901/33, 901/34, 73/862.04, 73/777, 73/865.7, 73/862.68, 294/86.4, 294/119.1, 294/907
• US Class Current: 294/86.4
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: B25J 15/0009 comprising multi-articulated fingers, e.g. resembling a human hand
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 5/162 of piezoresistors
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: Y10S 294/907 Sensor controlled device

Abstract

An elementary sensor for sensing a force comprises a transducer for transforming a mechanical deformation to an electric signal, and a first strain generative body (20) including a supporting portion (21) and a working portion (23) connected to the transducer so as to allow the transducer to produce a mechanical deformation on the basis of a displacement relative to the supporting portion of the working portion. By further adding a second strain generative body (30) including a fixed portion (31) fixed at least with respect to the direction of a force to be detected, and a displacement portion (33) connected to the working portion of the first strain generative body, wherein the displacement portion is constructed to produce a displacement based on a given external force relative to the fixed portion to transmit the displacement thus produced to the working portion of the first strain generative body, a force detector applicable to a wide variety of measurement ranges can be realized. Moreover, by allowing the displacement portion to be elongated, a detector suitable for measurement of both force and moment can be provided. In addition, a stylus (306) can be connected to the elementary sensor to apply it to a contact detector, and the elementary sensor can be affixed at the hand of a robot to apply it to a gripper for the robot.

Claims

1. A gripper for a robot comprising:

a right finger member and a left finger member, a work being held between said right finger member and said left finger member;

a right intermediate member and a left intermediate member;

a hand member for movably supporting said right intermediate member and said left intermediate member;

drive means for moving said right intermediate member and said left intermediate member with respect to said hand member;

a right strain generative body made of metal having a supporting portion and a working portion, said supporting portion being fixed to said right intermediate member, said working portion being fixed to said right finger member, and said right strain generative body generating a strain based on a mechanical deformation caused by a displacement between said supporting portion and said working portion;

a left strain generative body made of metal having a supporting portion and a working portion, said supporting portion being fixed to said left intermediate member, said working portion being fixed to said left finger member, and said left strain generative body generating a strain based on a mechanical deformation caused by a displacement between said supporting portion and said working portion;

a right substrate made of semiconductor attached to said right strain generative body so that a strain generated by said right strain generative body is transmitted to said right substrate, said right substrate having a single crystal structure;

a left substrate made of semiconductor attached to said left strain generative body so that a strain generated by said left strain generative body is transmitted to said left substrate, said left substrate having a single crystal structure;

right resistance elements having a piezo resistance effect wherein electric resistance changes due to a mechanical deformation, said right resistance elements being formed on said right substrate;

left resistance elements having said piezo resistance effect, said left resistance elements being formed on said left substrate; and

means for detecting a condition for holding said work by measuring resistance values of said right resistance elements and said left resistance elements.

2. A gripper for a robot as set forth in claim 1 wherein the right strain generative body and the left strain generative body have a flexible portion located between the supporting portion and the working portion, a thickness in said flexible portion being thinner than that in said supporting portion and said working portion so as to obtain flexibility.

3. A gripper for a robot as set forth in claim 2 wherein the working portion is located in a central part of the strain generative body, the flexible portion being located in a peripheral part of said working portion and the supporting portion being located in a peripheral part of said flexible portion.

4. A gripper for a robot as set forth in claim 1 wherein the right resistance elements and the left resistance elements are arranged on the substrates in a way such that three axial components exerted to said substrates can be detected.

5. A gripper for a robot as set forth in claim 1 wherein the right resistance elements and the left resistance elements are arranged on the substrates in a way such that three dimensional forces and moments exerted to said substrates can be detected.

6. A gripper for a robot comprising:

a right finger member and a left finger member, a work being held between said right finger member and said left finger member;

a right intermediate member and a left intermediate member, said left intermediate member being connected to said left finger member;

a hand member for supporting said right intermediate member and said left intermediate member, at least one of said intermediate members being movably supported as a movable member;

drive means for moving said movable member with respect to said hand member;

a strain generative body made of metal having a supporting portion and a working portion, said supporting portion being fixed to said right intermediate member, said working portion being fixed to said right finger member, and said strain generative body generating a strain based on a mechanical deformation caused by a displacement between said supporting portion and said working portion;

a substrate made of semiconductor attached to said strain generative body so that a strain generated by said strain generative body is transmitted to said substrate, said substrate having a single crystal structure;

resistance elements having a piezo resistance effect wherein electric resistance changes due to a mechanical deformation, said resistance elements being formed on said substrate; and

means for detecting a condition for holding said work by measuring resistance values of said resistance elements.

7. A gripper for a robot as set forth in claim 6 wherein the strain generative body has a flexible portion located between the supporting portion and the working portion, a thickness in said flexible portion being thinner than that in said supporting portion and said working portion so as to obtain flexibility.

8. A gripper for a robot as set forth in claim 7 wherein the working portion is located in a central part of the strain generative body, the flexible portion being located in a peripheral part of said working portion and the supporting portion being located in a peripheral part of said flexible portion.

9. A gripper for a robot as set forth in claim 6 wherein the resistance elements are arranged on the substrates in a way such that three axial components exerted to said substrates can be detected.

10. A gripper for a robot as set forth in claim 6 wherein the resistance elements are arranged on the substrates in a way such that three dimensional forces and moments exerted to said substrates can be detected.