CN102928137A - Four-interdigital-electrode type three-dimensional force contact sensor for artificial skin - Google Patents

Abstract

The invention discloses a four-interdigital-electrode type three-dimensional force contact sensor for artificial skin. The four-interdigital-electrode type three-dimensional force contact sensor is characterized in that four same interdigital electrodes are symmetrically arranged on the same one plane and mutually form 90 degrees; pressure sensitive material layers cover the interdigital electrodes to form resistors R1, R2, R3 and R4 respectively; and the upper surface of the pressure sensitive material is covered with a hemispherical contact to form a three-dimensional force contact sensing unit arranged on the surface of a detected zone.

Description

Artificial skin is with four interdigital electrode formula 3 D force-touch sensors

Technical field

The invention belongs to field of sensing technologies, relate in particular to a kind of 3 D force-touch sensor that is applied to robot.

Background technology

Along with the development of Robotics, the research of touch sensor has received increasing concern.At present comparatively ripe to the research of one-dimensional power sensor, but as the intelligent skin of robot, not only need sensor can realize the detection of effects on surface pressure at right angle, also need the shearing force that sensor can the detection level direction simultaneously.When gripping object such as robot, need the perception tangential force, simultaneously perception positive pressure.When robot contacts the object of some surface imperfections, need to realize the detection of three-dimensional even multi-dimensional direction power.The development of 3 D force-touch sensor has become intelligent robot technology's a important research field.

Develop at present multiple three-dimensional force sensor both at home and abroad, be used for robot skin.The mode that the people such as Van A H of Japan utilize the MEMS technology to paste pressure-sensitive film resistance in the rood beam structure has been made the 3 D force-touch sensor that is used for the robot finger; The people such as Huang of Taiwan National Chenggong University utilize crooked platinum/titanium film, one section is fixed and be arranged to the rood beam structure, have made the touch sensor for detection of vertical force and shearing force; The people such as Su of Taiwan National Tsing Hua University generate anisotropic carbon nano-tube at silicon substrate, but and with its transfer and revolve the flexible touch sensation sensor that figure has made detection of vertical power and shearing force to the PDMS; These sensors that are used for measurement three-dimensional force information mainly adopt metal or metal oxide rood beam or semiconductor material etc., and these materials all are rigid materials, do not have flexibility.

The people such as Chen are take PDMS and PET as matrix material, but ITO has made the flexible capacitance type touch sensor of detection of vertical and shearing force as electrode; The people such as Xu Fei of Hefei intelligent machine research institute of Chinese University of Science and Technology are take carbon black/silicon rubber as matrix material, and are routed to criss-cross construction in the material internal levels, have made the three-dimensional force flexible touch sensation sensor, have realized three-dimensional force measurements.Though this three-dimensional force sensor that utilizes conductive rubber to make has certain flexibility, the Form Characteristic of its electrode and force-sensitive material double contact causes the sensor production process that very large difficulty is arranged, and also unreliable in stability and sensitivity.

Summary of the invention

The present invention be for the artificial sensitive skin of intelligent robot provide a kind of flexible, precision is high, the artificial skin of the flexibility of stable performance is with four interdigital electrode formula 3 D force-touch sensors.

The present invention is that the technical solution problem adopts following technical scheme:

The artificial skin of the present invention with the design feature of four interdigital electrode formula 3 D force-touch sensors is: on flexible PCB, four identical interdigital electrodes are in and are mutually 90 ° of symmetry arrangement on the same plane; Cover layer of pressure sensitive in described each interdigital electrode and form respectively resistance R ₁, resistance R ₂, resistance R ₃And resistance R ₄, be coated with the three-dimensional force tactile sensing unit that semisphere contact formation is arranged on detected region surface at the upper surface of described layer of pressure sensitive.

The artificial skin of the present invention also is with the design feature of four interdigital electrode formula 3 D force-touch sensors:

Described each three-dimensional force tactile sensing unit is at the detected region surface formation 3 D force-touch sensor that is arranged in array.

Described layer of pressure sensitive is take flexible pressure-sensitive conductive rubber as material, and described flexible pressure-sensitive conductive rubber is carbon black-filled in silicon rubber.

Described semisphere contact is as material take tygon.

In described three-dimensional force tactile sensing unit, described layer of pressure sensitive independently covers on each single interdigital electrode, is to connect as one structure with silicon rubber between the layer of pressure sensitive that covers on described each interdigital electrode.

Three-dimensional force is pressed following formula and is resolved acquisition in the described three-dimensional force tactile sensing unit:

$k_x{F}_x=\frac{{\mathrm{\&Delta;<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/R_2-{\mathrm{\&Delta;R}}_4/R_4}{2}$

$k_y{F}_y=\frac{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/R_1-{\mathrm{\&Delta;<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/R_3}{2}$

$k_z{F}_z=\frac{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+{\mathrm{\&Delta;<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+{\mathrm{\&Delta;<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3+{\mathrm{\&Delta;R}}_4/R_4}{4}$

In the formula:

F _x, F _y, F _zBe respectively the semisphere contact at x, y and three suffered acting forces of direction of z;

k _x, k _yAnd k _zBe respectively the three-dimensional force sensing unit for directed force F _x, F _y, F _zResistance coefficient, described k _x, k _yAnd k _zObtain through Experimental Calibration;

R ₁, R ₂, R ₃And R ₄The initial resistance of resistance that is respectively three-dimensional force tactile sensing unit on the y axle positive dirction under the stress not, the initial resistance of resistance on the x axle positive dirction, the initial resistance of resistance on the y axle negative direction, the initial resistance of resistance on the x axle negative direction;

Δ R ₁, Δ R ₂, Δ R ₃With Δ R ₄Respectively the R of three-dimensional force tactile sensing unit after stressed ₂, R ₂, R ₃And R ₄Variable quantity.

Compared with the prior art, beneficial effect of the present invention is embodied in:

1, the artificial skin of the present invention is made materials with all of four interdigital electrode formula 3 D force-touch sensors and is comprised interdigital electrode, force-sensitive material, and contact is flexible material, satisfies artificial skin to the requirement of flexibility.

2, four interdigital electrode structures on the flexible PCB of the present invention have taken into full account the coupled relation between the different directions, but stability sensitivity that can the Effective Raise sensor.

2, three-dimensional force sensor of the present invention adopts pressure-sensitive conductive rubber to contact with the flexible PCB single face, and simple than two-sided layout electrode contact structure, manufacture craft is simple.

3, pressure-sensitive conductive rubber, interdigital electrode are resilient material among the present invention, allow three-dimensional force sensor to realize flexural deformation, whole touch sensor can be attached on the various curved surfaces reliably, realize three-dimensional force measurements, improve its flexible and surperficial adaptability.

What 4, the range of three-dimensional force of the present invention and sensitivity can be by the component ratio of contained carbon black in the pressure sensitive material and electrode finger beam and sizes is controlled, and range of adjustment is wide.

Description of drawings

Fig. 1 is the cross-sectional structure schematic diagram that the present invention is based on the touch sensor of compliant conductive rubber;

Fig. 2 a is flexible PCB cellular construction schematic diagram among the present invention;

Fig. 2 b is four equivalent resistance position distribution of three-dimensional force sensor schematic diagram among the present invention;

Number in the figure: 1 semisphere contact; 2 layer of pressure sensitive; 3 flexible PCBs; 4 interdigital electrodes.

Embodiment

Referring to Fig. 1, Fig. 2 and Fig. 3, artificial skin with the version of four interdigital electrode formula 3 D force-touch sensors is in the present embodiment: on flexible PCB 3, four identical interdigital electrodes 4 are in and are mutually 90 ° of symmetry arrangement on the same plane; Cover layer of pressure sensitive 2 in each interdigital electrode 4 and form respectively resistance R ₁, resistance R ₂, resistance R ₃And resistance R ₄, be coated with the three-dimensional force tactile sensing unit that semisphere contact 1 formation is arranged on detected region surface at the upper surface of layer of pressure sensitive 2.

In the implementation, each three-dimensional force tactile sensing unit is at the detected region surface formation 3 D force-touch sensor that is arranged in array; Layer of pressure sensitive 2 is take flexible pressure-sensitive conductive rubber as material, and flexible pressure-sensitive conductive rubber is carbon black-filled in silicon rubber; Semisphere contact 1 is as material take tygon;

Layer of pressure sensitive independently covers on each single interdigital electrode, is to connect as one structure with silicon rubber between the layer of pressure sensitive that covers on each interdigital electrode.

Three-dimensional force is pressed following formula and is resolved acquisition in the three-dimensional force tactile sensing unit:

$k_x{F}_x=\frac{{\mathrm{\&Delta;<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/R_2-{\mathrm{\&Delta;R}}_4/R_4}{2}$

$k_y{F}_y=\frac{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/R_1-{\mathrm{\&Delta;<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/R_3}{2}$

$k_z{F}_z=\frac{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+{\mathrm{\&Delta;<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00002401182500011.png,HDA00002401182500013.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+{\mathrm{\&Delta;<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="HDA00002401182500011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3+{\mathrm{\&Delta;R}}_4/R_4}{4}$

In the formula:

F _x, F _y, F _zBe respectively the semisphere contact at x, y and three suffered acting forces of direction of z;

k _x, k _yAnd k _zBe respectively the three-dimensional force sensing unit for directed force F _x, F _y, F resistance coefficient, k _x, k _yAnd k _zObtain through Experimental Calibration;

R ₁, R ₂, R ₃And R ₄The initial resistance of resistance that is respectively three-dimensional force tactile sensing unit on the y axle positive dirction under the stress not, the initial resistance of resistance on the x axle positive dirction, the initial resistance of resistance on the y axle negative direction, the initial resistance of resistance on the x axle negative direction;

Δ R ₁, Δ R ₂, Δ R ₃With Δ R ₄Respectively the R of three-dimensional force tactile sensing unit after stressed ₁, R ₂, R ₃And R ₄Variable quantity.

In Fig. 1: form a hard-packed integral body by semisphere contact 1, layer of pressure sensitive 2 and the flexible PCB 3 that is provided with interdigital electrode 4 from top to bottom based on the touch sensor of flexible pressure-sensitive conductive rubber.

In Fig. 2 a and Fig. 2 b, four interdigital electrodes 4 and layer of pressure sensitive 2 are electrically connected and form four equivalent resistances, realize that three-dimensional force detects.

The mechanism that three-dimensional force information is detected is as follows: three-dimensional force acts on layer of pressure sensitive 2 by semisphere contact 1, and layer of pressure sensitive and four interdigital electrodes contact equivalent resistance R ₁, R ₂, R ₃And R ₄Resistance will change when being subject to strain.Can realize three-dimensional force F by the measurement to four resistance variations _x, F _y, F _zDetection.

According to existing research, the size of flexible circuit plate electrode is big or small influential to strain output all with the distance of electrode.

Work as F _xDo the time spent, R ₁Be subject to compressive strain resistance and reduce R ₃Stretching strain resistance increases, and R ₂With R ₄The strain that two ends are subject to is cancelled out each other, and resistance variations is ignored.

Work as F _yDo the time spent, R ₂Be subject to compressive strain resistance and reduce R ₄Stretching strain resistance increases, and R ₁With R ₃The strain that two ends are subject to is cancelled out each other, and resistance variations is ignored.

Work as F _zDo the time spent, R ₁, R ₂, R ₃, R ₄Be subject to the compressive strain of equal extent, four resistance reduce on an equal basis.

The sensor output voltage signal is input to computing machine and processes through matrix operation through switching gate circuit, voltage contrasting amplified circuit, Data collecting conversion, obtains F _x, F _y, F _zValue.

The touch sensor that the present invention is based on flexible pressure-sensitive conductive rubber can be made by following technique:

At first, adopt standard flexible PCB manufacturing technology to make flexible PCB 3; Adopt screen printing technique to make interdigital electrode 4 at flexible PCB 3, adopt the room temperature synthesis technique to make layer of pressure sensitive 2; Wherein, the pressure sensitive material that is used for making layer of pressure sensitive 2 is in " functional material " second phase in 2010, and " being used for the conducing composite material research of composite flexible touch sensor " of being delivered by people such as Zhao Xing, Huang Ying has open report; Semisphere contact 1 adopts resin material, and semisphere contact 1 is bonded on the layer of pressure sensitive 2.

Afterwards, touch sensor based on flexible pressure-sensitive conductive rubber is demarcated, with the pressure repeated action of different sizes in sensor and detect respectively resistance value and the relation of exerting pressure at the situation lower sensor of different pressures, with this sensor is demarcated, by extract and process three voltage signals that the responsive unit of each three-dimensional force is exported in the responsive array of three-dimensional force under the three-dimensional contact force effect, obtain linear coupling relation between stressed and three voltage signals of all directions through linear decoupling zero, obtain coupled relation between each sensing unit through neural network decoupling again.

Claims (6)

1. artificial skin is with four interdigital electrode formula 3 D force-touch sensors, and it is characterized in that: on flexible PCB (3), four identical interdigital electrodes (4) are in and are mutually 90 ° of symmetry arrangement on the same plane; Cover layer of pressure sensitive (2) in described each interdigital electrode (4) and form respectively resistance R ₁, resistance R ₂, resistance R ₃And resistance R ₄, be coated with the three-dimensional force tactile sensing unit that semisphere contact (1) formation is arranged on detected region surface at the upper surface of described layer of pressure sensitive (2).

2. artificial skin according to claim 1 is characterized in that with four interdigital electrode formula 3 D force-touch sensors: described each three-dimensional force tactile sensing unit is at the detected region surface formation 3 D force-touch sensor that is arranged in array.

3. artificial skin according to claim 1 is with four interdigital electrode formula 3 D force-touch sensors, it is characterized in that: described layer of pressure sensitive (2) is take flexible pressure-sensitive conductive rubber as material, and described flexible pressure-sensitive conductive rubber is carbon black-filled in silicon rubber.

4. artificial skin according to claim 1 is with four interdigital electrode formula 3 D force-touch sensors, and it is characterized in that: described semisphere contact (1) is as material take tygon.

5. artificial skin according to claim 1 is with four interdigital electrode formula 3 D force-touch sensors, it is characterized in that: in described three-dimensional force tactile sensing unit, described layer of pressure sensitive independently covers on each single interdigital electrode, is to connect as one structure with silicon rubber between the layer of pressure sensitive that covers on described each interdigital electrode.

6. artificial skin according to claim 1 is characterized in that with four interdigital electrode formula 3 D force-touch sensors: three-dimensional force is pressed following formula and is resolved and obtain in the described three-dimensional force tactile sensing unit:

$k_x{F}_x=\frac{{\mathrm{\&Delta;R}}_2/R_2-{\mathrm{\&Delta;R}}_4/R_4}{2}$

$k_y{F}_y=\frac{{\mathrm{\&Delta;R}}_1/R_1-{\mathrm{\&Delta;R}}_3/R_3}{2}$

$k_z{F}_z=\frac{{\mathrm{\&Delta;R}}_1/R_1+{\mathrm{\&Delta;R}}_2/R_2+{\mathrm{\&Delta;R}}_3/R_3+{\mathrm{\&Delta;R}}_4/R_4}{4}$

In the formula:

F _x, F _y, F _zBe respectively the semisphere contact at x, y and three suffered acting forces of direction of z;

k _x, k _yAnd k _zBe respectively the three-dimensional force sensing unit for directed force F _x, F _y, F _zResistance coefficient, described k _x, k _yAnd k _zObtain through Experimental Calibration;

R ₁, R ₂, R ₃And R ₄The initial resistance of resistance that is respectively three-dimensional force tactile sensing unit on the y axle positive dirction under the stress not, the initial resistance of resistance on the x axle positive dirction, the initial resistance of resistance on the y axle negative direction, the initial resistance of resistance on the x axle negative direction;

Δ R ₁, Δ R ₂, Δ R ₃With Δ R ₄Respectively the R of three-dimensional force tactile sensing unit after stressed ₁, R ₂, R ₃And R ₄Variable quantity.

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