GB2115556A - Tactile sensor - Google Patents

Tactile sensor Download PDF

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Publication number
GB2115556A
GB2115556A GB8305302A GB8305302A GB2115556A GB 2115556 A GB2115556 A GB 2115556A GB 8305302 A GB8305302 A GB 8305302A GB 8305302 A GB8305302 A GB 8305302A GB 2115556 A GB2115556 A GB 2115556A
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GB
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Application
Patent type
Prior art keywords
mat
sensor according
array
electrodes
material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8305302A
Other versions
GB8305302D0 (en )
Inventor
Dennis Laurence Lewis
Bruce Elphinston Robertson
Anthony John Walkden
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00Measuring arrangements characterised by the use of electric or magnetic means
    • G01B7/003Measuring arrangements characterised by the use of electric or magnetic means for measuring position, not involving coordinate determination
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress in general
    • G01L1/20Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/205Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using distributed sensing elements

Abstract

In a tactile sensor of the kind comprising a compressible mat (1) of electrically resistive material and an array of electrodes (3, 5) on at least one main face of the mat, the electrically resistive material comprise carbon fibre having a resistivity of not less than 0.5 x 10<-3> ohm metres. The mat may in the form of carbon fibre filaments compacted into a matrix to form a felt like material or a cloth woven from a yarn of carbon fibres. Information regarding the shape, position or pressure exerted by an object can be obtained by scanning the resistance between pairs of electrodes. The sensed output may be fed to a microprocessor. <IMAGE>

Description

SPECIFICATION Tactile sensors This invention relates to tactile sensors.

More particularly the invention relates to tactile sensors of the kind (hereinafter referred to as the kind specified) comprising a compressible mat of electrically resistive material and an array of electrodes on at least one main face of the mat.

Typically there is an electrode array on each main face of the mat, each array comprising a series of parallel spaced apart conductors with the conductors of one array extending transversely to the conductor of the other array.

In use of such a sensor information regarding the shape and position of an object contacting the sensor and the pressure exerted by the object, can be obtained by scanning the resistance between pairs of the electrodes.

Known forms of tactile sensor of the kind specified suffer from a number of disadvantages, in particular that the variation of resistance with pressure exhibits hysteresis, and in the case of mats made of plastics materials, that resistance varies with the time that pressure is applied. In addition, the range through which the resistance varies with change of pressure is often not suitable for interfacing with standard transistor circuits.

It is an object of the present invention to provide a tactile sensor of the kind specified wherein these disadvantages are alleviated.

The present invention provides a tactile sensor of the kind specified in which the electrically resistive material comprises carbon fibres having a resistivity of not less than 0.5 x 10-3 ohm metres.

The mat suitably comprises carbon fibre filaments compacted into a matrix to form a felt iike material.

One tactile sensor in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of the sensor; Figure 2 is a circuit diagram of a scanning circuit for use with the sensor; and Figure 3 is a sectional view of the sensor of Figure 1 housed in a protective casing.

Referring to Figure 1 , the sensor comprises a mat 1 made of short carbon fibre filaments compacted into a matrix to form a felt-like material, the fibre filaments having a resistance of not less than 10 megohms per metre length of filament.

On each main face of the array there is provided an array of electrodes in the form of parallel spaced strips 3 or 5, the strips 3 on one main face extending at right angles to the strips 5 on the other main face.

In use the sensor is connected with a scanning circuit arrangement, one suitable scanning circuit being shown in Figure 2.

The circuit comprises a voltage source V whose negative terminal is connected to ground and whose positive terminal is connected via respective switches 7 and amplifiers 9 to each of the electrodes 5 on one main face of the mat. The electrodes 3 on the other main face of the mat are connected via respective switches 11 to one end of a reference resistor 1 3 whose other end is grounded. The ungrounded end of the resistor 1 3 is also connected to the input of a further amplifier 1 5 whose output is connected via respective resistors 17 to the inputs of the amplifiers 9.

In operation of the arrangement each of the switches 7 is closed in turn and whilst each switch 7 is closed, each of the switches 11 is closed in turn. The voltage across the resistance 13 is thus, in turn, representative of the resistance of the mat 1 at each of the locations on the mat 1 where an electrode 3 crosses an electrode 5.

The voltage across the resistance 13, which constitutes the output of the sensor, thus provides significant information regarding the shape, position and pressure exerted by an object placed on the sensor mat. The sensor output is suitably fed to a microprocessor (not shown) for storage, processing and display in any desired manner. It will be appreciated that the switches 3 and 11, which will normally be of the solid state type will also be operated under the control of the microprocessor.

In one particular form of the sensor described above with reference to Figure 1 the mat comprises a piece of felt-like material of thickness 1 millimetre consisting of a compacted matrix of carbon fibre filaments of nominal length 1 millimetre, nominal diameter 8 microns and resistance 57 megohms per metre length.

The spaced strips 3 or 5 forming each electrode array are suitably supported on a backing (not shown in Figure 1) lying on the side of the strips remote from the mat 1. The backings suitably project beyond the edges of the mat with the space between the projecting parts of the backings filled with a suitable material and the backings bonded to the filling material.

The electrode array strips 3 and 5 suitably consist of metal foil or silicone rubber loaded with metal, e.g. copper or silver. Alternatively, the electrode array may be formed by removing the insulation from end portions of the conductors of a multi-way cable and laying the stripped conductors out in parallel spaced relation, the cable then providing a lead to the electrode array.

To facilitate its use, the sensor of Figure 1 is preferably housed in a protective casing.

In one such arrangement, illustrated in Figure 3, the spaced strips 3 or 5 forming each electrode array are supported on a protective backing sheet 1 9 or 21 ,for example of thin plastics material, lying on the side of the strips remote from the mat 1. The backings 19 and 21 project beyond the edges of the mat 1 with the space between the projecting parts of the backings filled with a suitable material, such as strips 23 of the same material as the mat is made from, and with the backings 19 and 21 bonded to the strips 23 or other filling material.

It will be appreciated that whilst in the sensor described above by way of example the mat is in the form of carbon fibre filaments compacted into a matrix to form a felt like material, this is not necessarily the case in a sensor according to the invention. Thus the mat may, for example, be in the form of a cloth woven from a yarn formed of carbon fibres.

Claims (9)

1. A tactile sensor comprising a compressible mat of electrically resistive material and an array of electrodes on at least one main face of the mat wherein the electrically resistive material comprises carbon fibre having a resistivity of not less than 0.5 x 10-3 ohm metres.
2. A sensor according to Claim 1 wherein the mat comprises carbon fibre filaments compacted into a matrix to form a felt-like material.
3. A sensor according to Claim 2 wherein the filaments have a resistance of not less than 10 megohms per metre length of filament.
4. A sensor according to Claim 2 wherein the filaments have a nominal length of 1 millimetre, a nominal diameter of 8 microns and a resistance of 57 megohms per metre length.
5. A sensor according to any one of the preceding claims wherein the electrodes consist of metal foil.
6. A sensor according to any one of Claims 1 to 4 wherein the electrodes consist of silicone rubber loaded with metal.
7. A sensor according to any one of Claims 1 to 4 wherein the electrodes are formed by removing the insulation from end portions of the conductors of a multi-way cable and laying the stripped conductors out in parallel spaced relation, the cable then providing a lead to the electrode array.
8. A sensor according to any one of the preceding claims having an electrode array on each main face of the mat, each array comprising a series of parallel spaced apart conductors with the conductors of one array extending transversely to the conductors of the other array.
9. A sensor according to any one of the preceding claims wherein the mat and the or each electrode array is housed in a protective casing.
1 0. A sensor according to Claim 9 wherein the protective casing comprises two sheets of material, one on each side of the mat, which project beyond the edges of the mat with the space between the projecting parts of the sheet filled with a material to which the sheets are bonded.
1 A sensor according to Claim 10 wherein the electrodes of the or each electrode array are supported on the adjacent said sheet.
1 2. A tactile sensor substantially as hereinbefore described with reference to Figure 1 or Figure 3 of the accompanying drawings.
GB8305302A 1982-02-26 1983-02-25 Tactile sensor Withdrawn GB2115556A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB8205751 1982-02-26
GB8305302A GB2115556A (en) 1982-02-26 1983-02-25 Tactile sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8305302A GB2115556A (en) 1982-02-26 1983-02-25 Tactile sensor

Publications (2)

Publication Number Publication Date
GB8305302D0 true GB8305302D0 (en) 1983-03-30
GB2115556A true true GB2115556A (en) 1983-09-07

Family

ID=26282093

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8305302A Withdrawn GB2115556A (en) 1982-02-26 1983-02-25 Tactile sensor

Country Status (1)

Country Link
GB (1) GB2115556A (en)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2134719A (en) * 1983-01-31 1984-08-15 Alps Electric Co Ltd Tactile sensor
GB2137022A (en) * 1983-03-18 1984-09-26 Wright Barry Corp Tactile sensors for robotic gripper and the like
EP0161895A2 (en) * 1984-05-04 1985-11-21 Raychem Limited Sensor array
EP0187372A2 (en) * 1984-12-28 1986-07-16 Wacom Company, Ltd. Position detecting device
EP0206450A3 (en) * 1985-03-04 1988-01-13 Asahi Kasei Kogyo Kabushiki Kaisha Deformation sensitive electroconductive knitted or woven fabric and deformation sensitive electroconductive device comprising the same
GB2194057A (en) * 1986-08-14 1988-02-24 Microelectronics Applic Resear Tactile sensor device
GB2194102A (en) * 1986-07-17 1988-02-24 Schoeller & Co Elektrotech Sheet circuit
US4794365A (en) * 1985-10-02 1988-12-27 Raychem Limited Pressure sensor
DE8809052U1 (en) * 1988-07-14 1989-12-28 Blomberg Robotertechnik Gmbh, 4730 Ahlen, De
EP0520380A1 (en) * 1991-06-24 1992-12-30 Fel-Pro Incorporated Gasket with encased load sensor
US5222399A (en) * 1991-02-01 1993-06-29 Fel-Pro Incorporated Load washer
US5563354A (en) * 1995-04-03 1996-10-08 Force Imaging Technologies, Inc. Large area sensing cell
EP0964233A2 (en) * 1998-06-13 1999-12-15 Volkswagen Aktiengesellschaft Sensor for position and/or time resolved measurement of force or pressure
WO2005024371A1 (en) * 2003-09-09 2005-03-17 Qinetiq Limited Sensor and sensor array for monitoring a structure
US7145432B2 (en) * 2000-05-18 2006-12-05 Canesis Network Ltd. Flexible switching devices
US7584645B2 (en) * 2005-02-03 2009-09-08 Commissariat A L'energie Atomique Apparatus and method for measuring friction forces
CN100552398C (en) 2005-09-30 2009-10-21 重庆大学 Touch sensing costume for intelligent robot
US8065911B2 (en) 2004-07-07 2011-11-29 Wheelright Limted Vehicle tyre checking system

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2134719A (en) * 1983-01-31 1984-08-15 Alps Electric Co Ltd Tactile sensor
US4529959A (en) * 1983-01-31 1985-07-16 Alps Electric Co., Ltd. Input device
GB2137022A (en) * 1983-03-18 1984-09-26 Wright Barry Corp Tactile sensors for robotic gripper and the like
US4492949A (en) * 1983-03-18 1985-01-08 Barry Wright Corporation Tactile sensors for robotic gripper and the like
US4795998A (en) * 1984-05-04 1989-01-03 Raychem Limited Sensor array
EP0161895A2 (en) * 1984-05-04 1985-11-21 Raychem Limited Sensor array
EP0161895A3 (en) * 1984-05-04 1986-12-17 Raychem Limited Sensor array
EP0187372A2 (en) * 1984-12-28 1986-07-16 Wacom Company, Ltd. Position detecting device
EP0187372A3 (en) * 1984-12-28 1987-09-16 Wacom Company, Ltd. Position detecting device position detecting device
EP0206450A3 (en) * 1985-03-04 1988-01-13 Asahi Kasei Kogyo Kabushiki Kaisha Deformation sensitive electroconductive knitted or woven fabric and deformation sensitive electroconductive device comprising the same
US4794365A (en) * 1985-10-02 1988-12-27 Raychem Limited Pressure sensor
GB2194102A (en) * 1986-07-17 1988-02-24 Schoeller & Co Elektrotech Sheet circuit
EP0256799A2 (en) * 1986-08-14 1988-02-24 The Microelectronics Applications Research Institute Ltd. Tactile sensor device
EP0256799A3 (en) * 1986-08-14 1988-11-30 The Microelectronics Applications Research Institute Ltd. Tactile sensor device
GB2194057A (en) * 1986-08-14 1988-02-24 Microelectronics Applic Resear Tactile sensor device
GB2194057B (en) * 1986-08-14 1990-04-11 Microelectronics Applic Resear Tactile sensor device
US4866412A (en) * 1986-08-14 1989-09-12 The Microelectronics Applications Research Institute Limited Tactile sensor device
DE8809052U1 (en) * 1988-07-14 1989-12-28 Blomberg Robotertechnik Gmbh, 4730 Ahlen, De
US5222399A (en) * 1991-02-01 1993-06-29 Fel-Pro Incorporated Load washer
EP0520380A1 (en) * 1991-06-24 1992-12-30 Fel-Pro Incorporated Gasket with encased load sensor
US5563354A (en) * 1995-04-03 1996-10-08 Force Imaging Technologies, Inc. Large area sensing cell
EP0964233A2 (en) * 1998-06-13 1999-12-15 Volkswagen Aktiengesellschaft Sensor for position and/or time resolved measurement of force or pressure
EP0964233A3 (en) * 1998-06-13 2000-05-03 Volkswagen Aktiengesellschaft Sensor for position and/or time resolved measurement of force or pressure
US6216546B1 (en) 1998-06-13 2001-04-17 Volkswagen Ag Sensor arrangement for spatially and temporally varying measurements of force or pressure
US7145432B2 (en) * 2000-05-18 2006-12-05 Canesis Network Ltd. Flexible switching devices
US7301435B2 (en) 2000-05-18 2007-11-27 Peratech Limited Flexible switching devices
WO2005024371A1 (en) * 2003-09-09 2005-03-17 Qinetiq Limited Sensor and sensor array for monitoring a structure
US8065911B2 (en) 2004-07-07 2011-11-29 Wheelright Limted Vehicle tyre checking system
US7584645B2 (en) * 2005-02-03 2009-09-08 Commissariat A L'energie Atomique Apparatus and method for measuring friction forces
CN100552398C (en) 2005-09-30 2009-10-21 重庆大学 Touch sensing costume for intelligent robot

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Publication number Publication date Type
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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)