JPS60263690A - Tactile sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to the configuration of a tactile sensor suitable for use as a tactile device of a robot.

[Conventional technology]

Tactile sensors are used to detect the position and shape of objects in the gripping mechanisms of robots that perform tasks such as grasping and transporting objects. There are stylus-type ones, ones that use conductive rubber contacts, and ones that use pressure-sensitive conductive rubber. I had to put it together.

[Problems to be solved by the invention]

In this way, various conventional tactile sensors require electrical wiring for many elements arranged in a matrix, and many wirings are placed along the robot's arm, making it difficult for the robot to move smoothly. There was a problem in that it not only hindered the installation but also required extensive wiring work. Furthermore, this type of conventional sensor can only detect a two-dimensional planar position, and cannot detect the three-dimensional shape of an object, such as its curvature. Therefore, the present invention has been made in an attempt to eliminate the conventional drawbacks, and the present invention has been made to provide a flexible polymer piezoelectric sheet made of a polymer piezoelectric material as an element with two-dimensional By combining the arranged electrodes, the two-dimensional coordinates of the contact point are calculated by adding, subtracting, dividing, and integrating the potential of each electrode, which changes depending on the position when the sensing object contacts the polymer piezoelectric sheet and the state of sheet deformation. It is an object of the present invention to make it possible to easily detect the curve and curvature P, thereby making it possible to apply it to various robots in a crowded manner, and also to reduce the number of communication wiring and improve the detection accuracy. mouth to say

[Means to solve the problem]

However, an uninvented tactile sensor was developed using a polymer piezoelectric sheet,
It is composed of a coordinate detection line, an X coordinate detection line, and a curvature detection line, and includes a polymer piezoelectric sheet,
A single-layer structure of a laminate having a thin carbon-containing polymer film as a non-grounded body and a thin metal film as a grounded body in close contact with each other on both sides of two sheets made of a piezoelectric polymer material, or two sheets sandwiched between two sheets.
It forms a layered polymer structure and is made into one piece #1 by heating and pressure treatment. The carbon-containing polymer resistive thin film has lx
Electrodes are formed in large groups on both end sides facing each other in the X direction and on both end sides facing each other in the X direction perpendicular to the X direction, and are electrically and closely contacted, and are further subjected to polarization treatment. -1, the value obtained by subtracting the signals of two non-inverting amplifiers connected to the X-coordinate detection line and the two electrodes facing each other in the X-direction and the X-coordinate detection line. It has an arithmetic function that divides the signal by the sum of both signals. It also has an arithmetic function that detects the curvature of the object to be detected by adding the sum of the respective signals of the four non-inverting amplifiers to the five curvature detection lines and integrating this sum value.

[Effect]

The present invention having such a configuration is capable of attaching a polymer piezoelectric sheet to, for example, a finger of a robot along any of five curved planes, and also includes a device that calculates the X-direction coordinate, the X-direction coordinate, and the curvature. The number of connection wirings is kept to a minimum of four trees, and the number of detection information is four, making calculations easy and having the function of simultaneously detecting the curvature of the contact surface of the object to be detected together with the two-dimensional coordinates. However, the principle of detecting two-dimensional coordinates and curvature will be clarified by the explanation in the examples below. . [Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. FIG. 1 is a developed view schematically showing the structure of an example of the present invention, and FIGS. 2 to 4 show the structure of the polymer piezoelectric sheet in FIG. piezoelectric sea)
fl) l'j A sheet +21 made of a polymeric piezoelectric material such as polyvinylidene fluoride (PVDF) is sandwiched between the two sides.
Carbon-containing polymer resistive thin film (hereinafter abbreviated as resistive film)
(3) and metal thin film

[Hereinafter abbreviated as metal film] (The laminate formed by adhering 4J and

[Hot press] and make it into an integral structure. In addition, as the polymer piezoelectric material, in addition to PVDF, if the polymer material exhibits piezoelectricity, the A deviation can also be applied.
Examples include a resistive film [3] a thin sheet made by uniformly dispersing fine carbon particles in a nifluororesin. The polymer piezoelectric sheet thus constructed) [11 has one resistive film (3
) on both ends in the X direction [horizontal direction in Figure 1], an electrode [5xl] consisting of a strip-shaped part and a short strip-shaped part connected to the center part and tightly attached to the outer surface of the strip [5xl].

[5X] is coated with a resistive film (
3), and the electrodes [
5xl, [5yL (5y
] The above electrode [5xl, [5xl and electrode [5y], [5
It goes without saying that the polymer piezoelectric sheet 1111 with the above structure must be placed in a heating furnace and placed between the resistive film (31 and metal film +4) at a high temperature. Polarization treatment is performed by applying a DC voltage of a certain value and cooling it as it is to room temperature, and this polarization treatment causes the polymer material to exhibit substantial piezoelectricity.Then, the polarized sheet [ Each electrode [
After connecting each guiding green (t,] to (t4) to 5xl, , [5xl, (5y]j[5y]), paste it on the surface of an elastic plate, for example, a rubber plate [61].

[See Figure 1] Each electrode of il+ (5xl,
[5x) m [5y], conductor aEt connected to [5yl
, 2~[t4], X coordinate detection line +71.3
The + coordinate detection line (8) and the curvature detection line (9) are connected, but since the X coordinate detection line (7) and the y coordinate detection line (8) have the same structure, the X coordinate detection line (
7), each electrode [5x1. [5xl
A non-inverting amplifier [10xl] is connected to the end of the conductor @Et mountain [t,], and an adder [11! ] and the subtracter [12X] are connected in parallel, and the output terminal of the adder [11xl and the subtracter 1
The output terminal of the divider [12X] is connected to each input terminal of the divider [13xl], and the non-inverting amplifier [10X], [10x]
Both signals are subtracted by a subtracter t1zxl, and this value is divided by a divider (13X) using the sum value of both signals calculated by an adder [11xl as a divisor. -1 , curvature detection line (9), X coordinate detection line (7
) and the output terminal of the adder +11yl at the X coordinate detection line +81 are connected to each input terminal of the adder [11A], and the output terminal of the adder [11A] is The circuit is connected to the input terminal of the integrator (14), and the four non-reciprocal
IIIjil device [10x], [lOx], 110y
1. [1 Oyl (7) Calculate the total sum of each signal, and form the sum value so as to integrate it. These addition, subtraction, division by 1, and integration operations can be implemented using analog circuits, but non-inverting amplifiers [10X] and

[10y
) may be converted into a digital signal using a sex converter, input into a microcomputer, and processed using software. It should be noted that the metal film [4]ff is set aside for grounding. Next, when the object to be detected (ri) is pressed against the rectangular resistive film [3] by the above sensor [see Fig. 5]
, the principle of detecting the x and y coordinates on the resistive film (3) and the curvature of the strained shape for the position will be explained below. First, since the procedure is the same for the y-axis and the y-axis, we will consider the one-dimensional direction in the X-axis direction. When a piezoelectric material is pressed by a sensing object (b) and subjected to shape distortion as shown in Figure 5, polarization occurs and a voltage is generated between terminals (a) and (b). Figure 6 shows terminals (a) , (The vertical axis is the voltage generated during the interval, and the horizontal axis is time. As is clear from this diagram, if the state shown in Figure 5 is replaced with an electrical equivalent circuit, Figure 7 is shown. In other words, the object to be detected [hereinafter referred to as the workpiece] is represented by a capacitor that has a charge [Q,] at t=o in the pressed part.The resistive film [3] has a resistance against a rectangular surface. Since the resistance is uniformly distributed, the resistance value iRk on the right side [in Figure 5] of the contact point of the workpiece←] and the resistance value on the left side are expressed as RL.Now, as shown in Figure 7. , a detection circuit OQ is installed on both ends of the sensor, and the potential VLs'VR'E generated on the left and right sides is calculated. In this case, the ■ terminal of the operational amplifier [0, P] is connected to the metal film (4
) and ground in the same way. Vx, Ct, ) = −−7(t) ...−KL '7− If the contact point of p (w) is the variable X, −RL
# As shown in Figure 8, RR is expressed as a slide resistance. RL -RH== 2xR (1m,
Ro= RL + RR... From (c)', by substituting into equation (a) and (shiki-nan), from this equation (e), at a certain time 1 = 18, the coordinates of the contact point (g)
is determined from ``Rltels vL[tol.'' Next, we will explain the detection of curvature.The current flowing through RL in Fig. 7 is ↓L(tJ, and the current flowing through RR is i R(t
), where 0 is the virtual capacitor capacity. Therefore (to) expression? Laplace transform gives 1
' 1 1 Q(S)=av(S)+(-+-1-V(S)RR,R
LS, and V (SJ 'E-g through the integral element v'(S)
If you take it out as . Here, based on the results of the experiment, the electric charge generated when the workpiece (W) with the curvature (γ) is pressed against the workpiece (W), Q=x−a, T
2.γ... (SJK; proportionality constant d; pressure ratio T; thickness γ of the polymer piezoelectric material; curvature of the workpiece (b) has been obtained. Therefore, the workpiece (w) with a constant curvature γ0 The electric charge Q(S) generated when the From the final value theorem of transformation, by substituting the expression C and the expression ), we get ``Qo = Aim V'(t) −, (, yj)

[
l-χ2] From the Ro t-+ga diagram. From formula C01 (b), = −[V'B(t)+VL(tJ)(1-X2) −
--(LJ(Substituting the set into (dynamic equation) gives By subtracting VR(a, VL(tJ) from equation A, we can obtain the contact point (phantom X. 5x1., each 0 in [5X]

[Opposing electric current % [5y1. [53'] '
The same applies if you get stuck] by dividing the difference by the sum value to calculate the

The [X coordinate] is obtained as the displacement from the center point of the resistive film [3], and the counter electrode (5
The curvature in the X direction can be obtained by further integrating the sum value of each signal of xL [5x)'? i: It is clearly indicated, so to calculate the average curvature in the X direction and the X direction, each electrode [5x), [5x), [5yl
, [Each signal of 5yl

[Needless to say, all you need to do is add up and then integrate this. Polymer piezoelectric sheet of tactile sensor having the configuration and detection function described above) [11 shows m< shown in Fig. 17 (a) and [(b), when mounted on the finger of the robot hand part (b), Needless to say, it becomes a tactile sensor that provides information on the contact position and contact curvature.In this case, the first sensor is thin and flexible.
It can be easily attached to a finger with a curved surface similar to a human finger, as shown in Figure 7.The surface of the polymer piezoelectric sheet [1] is designed to prevent damage caused by contact with the workpiece (G). In order to prevent electric charge from leaking when it comes into contact with a metal workpiece (W), it is desirable to attach an insulating film, such as a fluororesin thin film. A polymer piezoelectric sheet T-[11 according to an example is shown, and the sheet (1)
, a resistive film (3), and a sheet 1f2 made of a polymeric piezoelectric material.
1. The metal film (4), the same sheet [2] as described above, and the resistive film (31) are sequentially stacked, pressurized, and heat-treated to form an integral structure, whereas the previous example had a single layer structure of a laminate. In this example, one side, for example, the first
In Figure 0, there is a resistive film on the top surface (31 is a counter electrode in the X direction).
5x) and the opposing electrode [5y] in the y direction to the resistive film (3) on the bottom surface.

The only difference from the previous example is that the X-coordinate system resistive film and the ). The combination with [81 and +91 and the detection function are the same as in the previous example. However, compared to the single-layer structure of the previous example [examples shown in Figures 1 to 3], it is slightly more complicated to manufacture and leads to higher costs. As shown in Figure 1, there is little distortion in the detection linearity of the first device, and the detection accuracy is considered to be slightly better.0 Also, compared to a single layer structure, the signal level extracted from each opposing electrode is doubled, so the S/N ratio is It has a high advantage. Next, Figures 12 to 15 show a polymer piezoelectric sheet (11) according to an embodiment of the present invention, which also has a two-layer polymer structure, but with a resistive film (3) at its center. A sheet (21) made of a polymeric piezoelectric material is adhered to both sides of the layer as a layer, and a metal film (21) as a grounding body is attached to the inner and outer surfaces of the sheet (21).
4) in close contact with one resistive film [X in 31].
direction, opposite electrode in the X direction (5xL [5xl, E5y1
．． (5yl is provided in the same manner as the above-mentioned single-layer structure example, and has exactly the same detection characteristics as the metal film in the central layer that picks up the signal (3
), the S/N ratio is enhanced compared to the single layer structure. There is no need to provide any particular insulation coating, and it can be attached to the robot's finger as is.

【Effect of the invention】

Since the flexible polymer piezoelectric sheet (11) of the present invention is used as a detection body in a tactile sensor, it can be easily mounted not only on a flat surface but also on a curved surface. It has versatility 2 that can be applied to various robots. Furthermore, since it is possible to simultaneously measure the X coordinate and the
) can make the robot's fingers perform a grasping motion that is adapted to the three-dimensional structure of the robot. In addition, since the number of conducting wires for transmitting signals when detecting the X coordinate, y coordinate, and curvature can be minimized to 4 trees (5 trees if the ground wire is included), the wiring process for the robot tactile sensor G is significant. It is easy to use, fits well around the hand, promotes smooth movement, and has great practical value.

[Brief explanation of drawings]

Fig. 1 is a developed view schematically showing the structure of an example of undeveloped J, Figs. 2 to 4 are plan views of the polymer piezoelectric sheet in Fig. 1, and a cross section along A-Am in Fig. 2. Figure and bottom view, 5th
9 to 8 are explanatory parts for showing the basis of the detection performance of the present invention, FIGS. 9 to 11 are plan views of a polymer piezoelectric sheet according to an embodiment of the present invention, and FIG. A cross-sectional view and a bottom view taken along line B7E, a plan view of a polymer piezoelectric sheet according to another embodiment of the present invention, and a-a in FIG. 12 are shown in FIGS.
FIG. 14 is a cross-sectional view taken along line a, a cross-sectional view taken along line D-D in FIG. 13, and a bottom view. In addition, Fig. 16 shows a positional linearity analysis diagram of each uninvented polymer piezoelectric sheet, Fig. 17), (
It is a diagram in which an uninvented tactile sensor is mounted on the fingers of a robot hand. [11... Polymer piezoelectric sheet s [2]... Sheet. [3] Carbon-containing polymer resistance thin film. (4)...Metal thin film, [5X]...X direction electrode. [5y...Y direction electrode, (7)...X coordinate detection line. (8)...Y coordinate detection line. (9) Curvature detection line. [10xl [loy]...Non-inverting amplifier. (W)...Detection target object. Fig. 5 Fig. 7 Fig. 8 Fig. 2 Fig. 16 (b) Two-layer structure (b) Fig. 17 of Kishibi-kei-kame 6

Claims (1)

[Claims] 1. A sheet made of a polymeric piezoelectric material (21) is sandwiched between the carbon-containing polymeric resistive thin film [3] as a non-grounded body and a metal thin film (4) as a grounded body. A single-layer structure or a two-layer polymer structure 2 of a laminate having the laminates in close contact with each other is integrally molded by heat and pressure treatment, and the sheet as a whole has flexibility that can be deformed in the thickness direction, and the above-mentioned Carbon-containing polymer resistive thin film (3I, electrodes [5X] on both end sides facing each other in the X direction and opposite ends in the X direction perpendicular to the A polymer piezoelectric sheet il+ which is closely attached to the il+ and further subjected to polarization treatment, and each electrode [5X] I [
5X] two non-inverting amplifiers connected to 110X]1
By subtracting both signals of [10X) and dividing this value by the sum of both signals, the polymer piezoelectric sheet (
1) an X-coordinate detection line (7) capable of outputting the X-coordinate of the detection object (W) in contact with the X-coordinate detection line (7), and each electrode [57] in the X direction;
Two non-inverting amplifiers [10y
The detection target (
b) can output the X coordinate of y! A mark detection line (8),
The four non-inverting amplifiers [OXI, [10X],
A curvature detection line (9) capable of outputting the curvature of the detection target ← J by calculating the sum of each signal of [1 Oyl, ['1 Oyl] and integrating this sum value. tactile sensor.