Tactile sensor

• US 4,616,511 A
• Filed: 02/20/1985
• Issued: 10/14/1986
• Est. Priority Date: 02/20/1985
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Gindy, Sherif S., Tremonti, Ronald R.
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US06/703,353
• Time in Patent Office: 601 Days
• Field of Search: 901/9, 901/33, 901/34, 901/46, 414/5, 414/730, 73/862.04, 177/211, 177/229
• US Class Current: 73/862.045
• CPC Class Codes: G01L 1/2206 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 5/1627 of strain gauges using piezoresistors G01L5/162

Abstract

A load plate is rigidly supported by a central pedestal strain gaged for bending about a central axis. In one embodiment, the pedestal is mounted to the center of a yoke bar supported by two legs strain gaged for comprehensive loads only the sum of which is indicative of the magnitude of the plate load. The legs are supported by base webs strain gaged for bending about a central axis orthogonal to the axis of pedestal bending. The output of the bending strain gages enables determination of the coordinates of the load location on the plate from the central axis axes.

In a second embodiment, the pedestal is supported by a block rigidly attached to the end of a cantilevered member extending at right angles from the pedestal. The cantilever member is strain gaged at two longitudinal stations for reading the differential of the bending strain to thereby determine the shear loading, or plate tactile load. One of the coordinates of the applied load on the plate is determined from the output of the pedestal bending strain gages and the other coordinate from one of these bending strain gage sets on the cantilever member.

An optional bellow over the cantilever member provides in reared torsional stiffness without decreasing bending sensitivity.

Claims

1. A tactile transducer for determining location and magnitude of an applied load upon a load plate comprising:

(a) an elongated vertically extending pedestal portion having the transverse section thereof having a greater width in one of two orthogonal directions, said pedestal portion movement deflection sensitive about an "Y" axis in the direction of said greater transverse width;

(b) a yoke bar portion having the base end of said pedestal portion attached intermediate the ends thereof;

(c) a plurality of spaced vertical load sensing leg portions disposed one at each opposite end of said yoke bar portion and joined integrally thereto in rigid moment deflection resisting attachment,

(d) a rigid transverse member interconnecting the opposite ends of said vertical load sensing leg members;

(e) at least one support member having one end thereof joined to said transverse member on and extending therefrom in a direction opposite said vertical load sensing leg poritons, said support member operatively moment sensitive about an "X" axis orthogonal to said "Y" axis;

(f) an attachment base portion on the end of said support member remote from said transverse member;

(g) said load plate rigidly secured to said pedestal in moment deflection resisting connection for transmitting therethrough moments applied to said plate; and

,

(h) electrical strain gage means disposed on said pedestal portion, said vertical load sensing leg portions and said support member, said strain gage means on all of said vertical load sensing leg portions having the signals therefrom summed to provide an indication of the total load F_z applied to said load plate, said strain gage means on said pedestal portion providing a signal indicative of the distance y in a direction normal to said "X" axis along said load plate from the center of said pedestal portion of application of F_z in accordance with the expression y=F_z /M_x wherein M_x is the bending moment of F_z about the "X" axis, said strain gage means on said support member providing a signal indicative of the distance x in a direction normal to said "Y" axis along said load plate from the center of said pedestal of application of F_z in accordance with the expression x=F_z /M_y, where M_y is the bending moment of F_z about the "X" axis.

2. A tactile transducer for determining loaction and magnitude of an applied load upon a load plate comprising:

(a) a reaction base having an elongated member resiliently deflectable in bending extending in cantilever therefrom in a first direction, said member having the transverse section thereof configured to render said member bendable about a "Y'"'"'" axis transverse to said first direction of elongation;

(b) an elongated pedestal member having one end rigidly attached to the end of said cantilever member, said attachment substantially unstrained under moment loads with said member extending at a right angle to said "Y" axis and said first direction of elongation of said cantilevered member, said pedestal member having the transverse action thereof configured to render said member bendable about an "X'"'"'" axis normal to said "Y'"'"'" axis and parallel to said first direction of elongation of said cantilevered member;

(c) a load plate member rigidly attached to the remaining end of said pedestal member in a manner generally unstrained under moment loads, said load plate adapted to receive a tactile load F_z anywhere on the surface thereof;

(d) electrical strain gage means disposed at a first longitudinal station L₁ on said cantilever member and operative to sense strain thereof due to bending about said "Y'"'"'" axis and operative to emit an electrical signal accordingly;

(e) electrical strain gage means disposed on said pedestal member and operative to sense bending strains thereof at said first station due to bending about an axis therethrough parallel to said "X'"'"'" axis and operative to emit an electrical signal M_x representative thereof; and

(f) electrical strain gage means disposed on said cantilever member at a second longitudinal station L₂ spaced or predetermined distance Δ

L from said first longitudinal station and operative to sense bending strains thereof at said second station dut to bending about an axis therethrough parallel to said "Y'"'"'" axis and operative to emit an electircal signal S₂ representative thereof, wherein the magnitude of the tactilely sensed load F_z is determined by the expression S₁ -S₂ /Δ

L, the distance x of F_z from the "Y'"'"'" axis is determined by the expression L-S₂, and the distance y of from the "X'"'"'" axis is determined by the expression M_x /F_z.

3. The tactile transducer defined in claim 2, further comprising tubular means disposed about said cantilever member having an end thereof anchored to the end of said member adjacent said reaction base and the other end of said tubular means anchored to the end of said member adjacent said rigid attachment to said pedestal member, said tubular means operative to substantially increase the torsional stiffness of said cantilever member without significantly altering the bending stiffness thereof.