Contact detector using resistance elements and its application

• US 5,263,375 A
• Filed: 09/25/1991
• Issued: 11/23/1993
• 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): Chilcot, Jr., Richard E.
• Assistant Examiner(s): Dougherty, Elizabeth L.
• Application Number:
  US07/765,588
• Time in Patent Office: 790 Days
• Field of Search: 73/862.04, 73/862.64, 73/862.68, 73/862.38, 73/862.54, 73/104, 73/105, 73/727, 73/862.044, 73/862.045, 73/286.042 , 73/862.637, 73/862.381, 73/862.541, 73/862.627, 338/5
• US Class Current: 73/862.042
• 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

Abstract

There is disclosed an applied technology of an elementary sensor for sensing a force comprising 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, an embodiment to connect stylus (306) to the elementary sensor to apply it to a contact detector, and an embodiment to affix the elementary sensor at the hand of a robot to apply it to a gripper for robot are disclosed.

Claims

1. A contact detector comprising:

a contact piece for contacting an object;

a strain generative body for transforming a force applied to said contact piece due to contact with an object to a mechanical deformation;

a semiconductor substrate connected to said strain generative body, said substrate including resistance elements having a resistance value varying on the basis of a mechanical deformation transformed by said strain generative body;

said strain generative body being made of a material different from said semiconductor substrate;

an enclosure for containing said strain generative body and said semiconductor substrate, an object contacting end of said contact piece protruding outwardly from said enclosure; and

supporting means for supporting said strain generative body within said enclosure;

said substrate having a flat surface, and wherein an XYZ three-dimensional coordinate system is defined including orthogonal X and Y axes lying in said flat surface and intersecting each other at an origin of said system, wherein said resistance elements are located on an XY plane of the coordinate system, said semiconductor substrate comprising first bridging portions (214,

     215) formed along the X-axis on respective both sides of the origin of the coordinate system and second bridging portions (212,

     213) formed along the Y-axis on respective both respective both sides of the origin, said first and second bridging portions being fixed to said strain generative body so that strains are produced in said respective bridging portions by applying a force to said contact piece; and

wherein resistance element groups (R) comprising a plurality of said resistance elements are provided on the XY plane of said first and second bridging portions at principal positions as follows;

a) a pair of positions for resistance elements (R13, R15) arranged on both sides of the X-axis in respective positive and negative directions of the Y-axis in the vicinity of said origin in the positive direction of said X-axis,

b) a pair of positions for resistance elements (R10, R12)) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said origin in the negative direction of said X-axis,

c) a pair of positions for resistance elements (R14, R16) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said fixed portion in the positive direction of said X-axis,

d) a pair of positions for resistance elements (R9, R11) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said fixed portion in the negative direction of said X-axis,

e) a pair of positions for resistance elements (R5, R7) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said origin in the positive direction of said Y-axis,

f) a pair of positions for resistance elements (R2, R4) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said origin in the negative direction of said Y-axis,

g) a pair of positions for resistance elements (R6, R8) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said fixed portion in the positive directions of said Y-axis, and

h) a pair of positions for resistance elements (R1, R3) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said fixed portion in the negative direction of said Y-axis.

2. A contact detector comprising:

a contact piece for contacting an object;

a strain generative body for transforming a force applied to said contact piece due to contact with an object to a mechanical deformation;

a semiconductor substrate connected to said strain generative body, said substrate including resistance elements having a resistance value varying on the basis of a mechanical deformation transformed by said strain generative body;

said strain generative body being made of a material different from said semiconductor substrate;

an enclosure for containing said strain generative body and said semiconductor substrate, an object contacting end of said contact piece protruding outwardly from said enclosure; and

supporting means for supporting said strain generative body within said enclosure;

wherein two sets, each comprising four of said resistance elements, are provided for detecting a component of contact along a respective one of at least two axes of a three-dimensional coordinate system; and

wherein said strain generative body includes a supporting portion secured to said enclosure by said supporting means, a working portion for receiving a force applied to said contact piece, and a flexible portion provided between an interconnecting said supporting portion and said working portion.

3. A contact detector as set forth in claim 2, wherein said working portion and said contact piece are resiliently connected.

4. A contact detector as set forth in claim 2, wherein said supporting means includes a supporting body fixed to said enclosure and having at least three supporting points on a surface thereof, a table plate supported by said supporting points, and a resilient member pressing said table plate toward said supporting points.

5. A contact detector as set forth in claim 2, wherein said supporting means includes a pedestal fixed to said enclosure and having an annular supporting edge on a surface thereof, a table plate having an annular groove in a first surface thereof, said plate being mounted on said supporting means by means of said annular edge extending into and contacting a surface of said annular groove;

and supporting portion of said strain generative body contacting a second surface of said table plate oppositely disposed to said first surface thereof, and a resilient member pressing said table plate toward said supporting edge.