CN102928137B - 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 four interdigital electrode formula 3 D force-touch sensors

Technical field

The invention belongs to field of sensing technologies, particularly relate to a kind of 3 D force-touch sensor being 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 force snesor, 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 sensor can the shearing force in detection level direction simultaneously.During as robot gripping object, need perception tangential force, the positive pressure of perception simultaneously.When the object of some surface imperfections of robotic contact, need to realize the three-dimensional even detection of multi-dimensional direction power.The development of 3 D force-touch sensor has become an important research field of intelligent robot technology.

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

The people such as Chen are with PDMS and PET for matrix material, and ITO has made the flexible capacitance type touch sensor that can detect vertical and shearing force as electrode; The people such as the Xu Fei of Hefei intelligent machine research institute of Chinese University of Science and Technology for matrix material, and are routed to criss-cross construction in material internal levels with carbon black/silicon rubber, have made three-dimensional force flexible touch sensation sensor, have achieved the detection to three-dimensional force.Though the three-dimensional force sensor utilizing conductive rubber to make this has certain flexibility, the Form Characteristic of its electrode and force-sensitive material double contact, cause sensor production process to have very large difficulty, and 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 four interdigital electrode formula 3 D force-touch sensors.

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

The artificial skin of the present invention design feature of four interdigital electrode formula 3 D force-touch sensors is: on flexible PCB, four identical interdigital electrode place mutual symmetry arrangement in 90 ° at grade; Described each interdigital electrode covers layer of pressure sensitive and forms resistance R respectively ₁, resistance R ₂, resistance R ₃with resistance R ₄, be coated with semisphere contact at the upper surface of described layer of pressure sensitive and form the three-dimensional force tactile sensing unit being arranged on detected region surface.

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

Described each three-dimensional force tactile sensing unit to be arranged in array formation 3 D force-touch sensor in detected region surface.

Described layer of pressure sensitive 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 take tygon as material.

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

In described three-dimensional force tactile sensing unit, three-dimensional force is pressed following formula and is resolved acquisition:

$k_x{F}_x=\frac{{\mathrm{\ΔR}}_2/R_2-{\mathrm{\ΔR}}_4/R_4}{2}$

$k_y{F}_y=\frac{{\mathrm{\ΔR}}_1/R_1-{\mathrm{\ΔR}}_3/R_3}{2}$

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

In formula:

F _x, F _y, F _zbe respectively the acting force of semisphere contact suffered by x, y and z tri-directions;

K _x, k _yand k _zbe respectively 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 in the y-axis positive dirction of three-dimensional force tactile sensing unit under non-stress, the initial resistance of resistance in x-axis positive dirction respectively, the initial resistance of the resistance in y-axis negative direction, the initial resistance of the resistance in x-axis negative direction;

Δ R ₁, Δ R ₂, Δ R ₃with Δ R ₄be respectively three-dimensional force tactile sensing unit stressed after R ₂, R ₂, R ₃and R ₄variable quantity.

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

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

2, four interdigitated electrode structure on flexible PCB of the present invention, have taken into full account the coupled relation between different directions, and the stability that effectively can improve sensor can sensitivity.

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

3, in the present invention, pressure-sensitive conductive rubber, interdigital electrode are resilient material, three-dimensional force sensor is allowed to realize flexural deformation, whole touch sensor is reliably attached on various curved surface, realizes the detection to three-dimensional force, improve its flexible and surperficial adaptability.

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

Accompanying drawing explanation

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

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

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

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

Embodiment

See Fig. 1, Fig. 2 and Fig. 3, in the present embodiment, the artificial skin version of four interdigital electrode formula 3 D force-touch sensors is: on flexible PCB 3, four identical interdigital electrode 4 place mutual symmetry arrangement in 90 ° at grade; Each interdigital electrode 4 covers layer of pressure sensitive 2 and forms resistance R respectively ₁, resistance R ₂, resistance R ₃with resistance R ₄, be coated with semisphere contact 1 at the upper surface of layer of pressure sensitive 2 and form the three-dimensional force tactile sensing unit being arranged on detected region surface.

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

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

In three-dimensional force tactile sensing unit, three-dimensional force is pressed following formula and is resolved acquisition:

$k_x{F}_x=\frac{{\mathrm{\ΔR}}_2/R_2-{\mathrm{\ΔR}}_4/R_4}{2}$

$k_y{F}_y=\frac{{\mathrm{\ΔR}}_1/R_1-{\mathrm{\ΔR}}_3/R_3}{2}$

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

In formula:

F _x, F _y, F _zbe respectively the acting force of semisphere contact suffered by x, y and z tri-directions;

K _x, k _yand k _zbe respectively 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 in the y-axis positive dirction of three-dimensional force tactile sensing unit under non-stress, the initial resistance of resistance in x-axis positive dirction respectively, the initial resistance of the resistance in y-axis negative direction, the initial resistance of the resistance in x-axis negative direction;

Δ R ₁, Δ R ₂, Δ R ₃with Δ R ₄be respectively three-dimensional force tactile sensing unit stressed after R ₁, R ₂, R ₃and R ₄variable quantity.

In FIG: the touch sensor based on flexible pressure-sensitive conductive rubber forms a hard-packed entirety 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.

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

The mechanism detected three-dimensional force information 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 ₄when being subject to straining, resistance will change.By realizing three-dimensional force F the measurement of four resistance variations _x, F _y, F _zdetection.

According to existing research, the size of flexible circuit plate electrode all has impact to the size that strain exports with the distance of electrode.

Work as F _xduring effect, R ₁be subject to compressive strain resistance to 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 _yduring effect, R ₂be subject to compressive strain resistance to 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 _zduring effect, R ₁, R ₂, R ₃, R ₄be subject to the compressive strain of equal extent, four resistance reduce on an equal basis.

Sensor output voltage signal is input to computing machine through matrix operation process 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 makes by following technique:

First, standard flex circuit board manufacturing technology is adopted to make flexible PCB 3; Adopt screen printing technique to make interdigital electrode 4 on flexible PCB 3, adopt room temperature synthesis technique to make layer of pressure sensitive 2; Wherein, for making the pressure sensitive material of layer of pressure sensitive 2 in " functional material " second phase in 2010, be publicly reported in " conducing composite material for composite flexible touch sensor is studied " of being delivered by people such as Zhao Xing, Huang Ying; Semisphere contact 1 adopts resin material, and semisphere contact 1 is bonded in layer of pressure sensitive 2.

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

Claims (5)

1. artificial skin four interdigital electrode formula 3 D force-touch sensors, is characterized in that: on flexible PCB (3), four identical interdigital electrode (4) place mutual symmetry arrangement in 90 ° at grade; Described each interdigital electrode (4) covers layer of pressure sensitive (2) and forms resistance R respectively ₁, resistance R ₂, resistance R ₃with resistance R ₄, be coated with semisphere contact (1) at the upper surface of described layer of pressure sensitive (2) and form the three-dimensional force tactile sensing unit being arranged on detected region surface; In described three-dimensional force tactile sensing unit, three-dimensional force is pressed following formula and is resolved acquisition:

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

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

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

In formula:

F _x, F _y, F _zbe respectively the acting force of semisphere contact suffered by x, y and z tri-directions;

K _x, k _yand k _zbe respectively 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 in the y-axis positive dirction of three-dimensional force tactile sensing unit under non-stress, the initial resistance of resistance in x-axis positive dirction respectively, the initial resistance of the resistance in y-axis negative direction, the initial resistance of the resistance in x-axis negative direction;

Δ R ₁, Δ R ₂, Δ R ₃with Δ R ₄be respectively three-dimensional force tactile sensing unit stressed after R ₁, R ₂, R ₃and R ₄variable quantity.

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

3. artificial skin according to claim 1 four interdigital electrode formula 3 D force-touch sensors, it is characterized in that: described layer of pressure sensitive (2) 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 four interdigital electrode formula 3 D force-touch sensors, is characterized in that: described semisphere contact (1) take tygon as material.

5. artificial skin according to claim 1 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 in each single interdigital electrode, is connect as one structure with silicon rubber between the layer of pressure sensitive that described each interdigital electrode covers.