Tactile load sensing transducer

• US 4,621,533 A
• Filed: 11/19/1984
• Issued: 11/11/1986
• Est. Priority Date: 11/19/1984
• 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.
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US06/672,544
• Time in Patent Office: 722 Days
• Field of Search: 73/65, 73/172, 73/432 KJ, 73/432 T, 73/862.04, 73/862.54, 73/862.65, 73/862.67, 178/18, 901/33, 901/46
• US Class Current: 73/862.045
• CPC Class Codes: G01G 3/1402 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 1/2218 the supports being of the column type, e.g. cylindric, adapted for measuring a force along a single direction
• CPC Class Codes: G01L 1/2262 involving simple electrical bridges
• CPC Class Codes: G01L 5/1627 of strain gauges using piezoresistors G01L5/162

Abstract

A tactile load sensing transducer for providing a continuous electrical readout indicative of the contact and the location of the load on a load receiving plate substantially simply supported by a plurality of reaction supports on the member. Each reaction support includes a member having a preferably integrally formed connecting portion of reduced transverse section so as to be substantially incapable of resisting moments generated by load plate deflection. Each support preferably has a generally "L" shaped configuration with the preferably integrally formed plate connecting portion formed adjacent the free end of one leg of the "L" so as to create bending strains in the support. Strain gages are provided on each support to sense the bending strains therein and, the gages on each support are connected in a common Wheatstone bridge to provide an indication of the reaction load on the support. A microprocessor circuit means sums the signals from the bridge to provide total load and also computes ratios of the individual support loads to the total to provide separate output signals for the x and y coordinates of the load location on the plate.

Claims

1. A tactile load sensing transducer comprising:

(a) a base member having a plurality of load cells mounted thereon in spaced apart relationship;

(b) a resiliently bendable member substantially simply supported by said load cells disposed at spaced apart margins of said bendable member;

(c) means defining a loading surface on said bendable member at any point intermediate the said load cells;

(d) circuit means operable to sum the signal outputs of said load cells to provide a continuous signal indicative of the total load on said bendable member and including means operable to determine the proportion of the total load on each load cell for providing indication of the location of said load along said bendable member.

2. The transducer defined in claim 1 wherein each of said load cells includes a reaction member and said summing circuit means includes a Wheatstone bridge having both tension and compression measuring strain gages disposed in adjacent arms thereof.

3. The transducer defined in claim 1, wherein each of said local cells includes a post having a generally "L" shaped configuration with a connecting portion attached adjacent the free end of one leg of said "L" shape and extending therefrom, said connecting portion being connected to the adjacent end of said bendable member, said post having strain gages thereon on the leg of said "L" shape remote from said connecting portion, said connecting portion having a relatively small transverse sectional area with respect to the transverse sectional area of said "L" shape and said bendable member, said connecting portion being substantially incapable of resisting moment loads applied thereto thereby rendering said bendable member effectively simply supported.

4. A tactile transducer comprising:

(a) a plate member disposed to receive against one surface thereof a load to be sensed;

(b) at least three reaction supports mounted on a base member and disposed in spaced relationship about said plate on the side thereof opposite said load receiving surface, said plate member being substantially simply supported at each of said supports such that no significant moment is applied to said supports by said plate member when loaded;

(c) strain gage means disposed on each of said supports and operable to provide an electrical signal indicative of the reaction load on each support;

(d) circuit means operable to sum said reaction load signals to provide a continuous signal indicative of the total load on said plate member;

said circuit means including means operable to provide the proportion of each reaction load signal with respect to said summed signal and means for indicating the distance of said load from each support thereby locating said load on said plate member.

5. The transducer defined in claim 4, comprising four said reaction supports disposed in equally spaced arrangement about said plate member.

6. The transducer defined in claim 4, wherein each of said supports includes a post having a generally "L" shaped configuration with one leg thereof rigidly mounted on said base member and a connecting portion attached adjacent the free end of the remaining leg of said "L" and extending therefrom, said connecting portions having the transverse section thereof small relative to the transverse section of the legs of said "L", said connecting portions being thereby substantially incapable of resisting any moment load applied thereto by said load receiving plate member, and said strain gage means provided on each of said "L" shaped posts for indicating the load thereon, whereby said plate member is effectively simply supported on each of said posts.

7. A tactile sensing load transducer comprising:

(a) base means;

(b) a load plate adapted to receive on one surface thereof the load to be sensed;

(c) at least three reaction support means connected to said plate adjacent the margins thereof and mounting said plate on said base means, said reaction support means each including a portion of reduced transverse thickness, said portion being substantially incapable of resisting moments applied thereto by said plate, with each of said support means including strain gage means operative to provide an electrical signal indicative of the individual reaction load on each of said reaction support means, said reduced thickness portions each being disposed to create bending strains in said support means;

(d) circuit means operable to sum the signal output of said strain gage means on each of said reaction support means, and including circuit means operable to determine the proportion of plate load on each support means for providing indication of location of said load along said load plate.

8. The transducer defined in claim 7, wherein each of said support means comprises an "L" shaped post having one leg thereof rigidly mounted on said base means with the said reduced section portion formed adjacent the free end of the remaining leg of said "L" shape.

9. The transducer defined in claim 7, wherein said strain gage means comprises electrical resistance means and said circuit means includes a Wheatstone bridge for the strain gage means on each of said support means and means for summing the output of each of said Wheatstone bridges.

10. A tactile load sensing transducer comprising:

(a) a base means;

(b) a load receiving member formed of resiliently deflectable material and having a generally elongated configuration;

(c) a plurality of reaction support members disposed on said base means in spaced relationship and each including structure connecting with said load receiving member adjacent a margin thereof and spaced in the direction of elongation, each connecting structure being substantially incapable of resisting moment loads applied thereto by loading of said load receiving member thereby rendering said load receiving member effectively simply supported;

whereupon loading of said load receiving member said connecting structure becomes operative to cause bending strain in said reaction support members;

(d) strain gage means operative to sense bending strain in said support members;

(e) first circuit means operable to continuously sum the signal outputs of said strain gage means and provide a continuous indication of the total load applied to said load receiving member; and

second circuit means operable to determine the proportion of load on each reaction support member to total load and thereby determine the distance of said applied load from any of said reaction support members.

11. The transducer defined in claim 10, wherein said load receiving member, said connecting structure and said plurality of reaction support members are formed integrally.

12. The transducer defined in claim 10, wherein said reaction support members are each rigidly mounted to said base means and said connecting structure comprises integral portions of said support members having a reduced transverse section for rendering said structure incapable of resisting moments.