JPH11118636A - Contact sensor and contact sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a contact sensor insusceptible to damage and to enable miniaturization by adhering piezoelectric elements on a base, providing a contact part so as to cover them, and arranging electrodes for the piezoelectric element. SOLUTION: In a triaxial contact sensor 22, a plurality of piezoelectric elements 30 are fixed to a base 38, and a contact part 28 with a protruded spherical surface which is an upper part provided so as to cover the piezoelectric elements 30 is in contact with an object to be contacted at a point. In addition, an electrode 36 is arranged on the center of each piezoelectric element 30 on the side of the base 38, and an electrode 34 is arranged on the center of each piezoelectric element 30 on the side of the contact part 28. Then wiring with its one end connected to the electrode 36 is arranged for a wiring board via a through hole 32 of the base 38 adhered to the wiring board, and the other end is connected to a switching element. Wiring with its one end connected to the electrode 34 is arranged for the wiring board via a through hole 33 of the base 38, and the other end is connected to a switching element. At this time, as piezoelectric elements are rigid and small by nature, it is possible to make the contact sensor insusceptible to damage and to enable miniaturization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact sensor and a contact sensor device, and more particularly, to a contact sensor for detecting a force received by contacting an object to be contacted and a contact sensor device provided with the contact sensor. .

[0002]

2. Description of the Related Art At present, a contact sensor is generally of a uniaxial detection type for detecting a force in a uniaxial direction.
The three-axis detection type, which detects three axial forces, is a stage at which a basic principle has been proposed by academic societies and the like.

[0003] Currently proposed three-axis contact sensors include a semiconductor type (diffusion gauge (using an O-ring or a beam)) and a light detection type (optical waveguide).

[0004]

However, a semiconductor type contact sensor is fragile and fragile due to its structure. The light detection type contact sensor requires a light source, a camera, and the like, resulting in an increase in size.

Further, these contact sensors only detect force. The present invention has been made in view of the above facts,
An object of the present invention is to propose a contact sensor that is hard to break and can be reduced in size and a contact sensor device including the contact sensor.

[0006]

In order to achieve the above object, a first method is provided.
The invention of at least one piezoelectric element fixed on a base, and a contact portion provided to cover the piezoelectric element,
And an electrode disposed on the piezoelectric element.

As described above, since the piezoelectric element is provided and the piezoelectric element is hard and small in nature, the contact sensor can be hardly broken, that is, the impact resistance can be improved and the size can be reduced.

According to a second aspect, the contact sensor of the first aspect, voltage detecting means for detecting a voltage generated at the electrode, application means for applying a voltage to the electrode, and a posture of the contact portion are changed. And control means for controlling the voltage applied by the application means.

Here, when the contact portion comes into contact with the contacted object and receives a force from the contacted object, a voltage having a magnitude corresponding to the amount of the received force is generated at the electrode. Therefore, if the voltage generated at the electrode is detected by the voltage detecting means,
The force that the contact portion receives from the contacted object can be obtained from the detected voltage.

[0010] On the other hand, the shape of a piezoelectric element changes depending on the magnitude and polarity of an applied voltage.

Therefore, by controlling the voltage applied by the application means so that the posture of the contact portion changes, the posture of the contact portion can be set to a desired posture. Therefore, in addition to the detection of the force, the posture of the contact portion can be set to a desired posture, and a multifunctional contact sensor device can be obtained.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, a three-axis contact sensor array 18 according to the contact sensor device according to the present embodiment is attached to the tip of each of a pair of arms 14 of a holding robot 10 that holds an object 20 to be held. ing. A pair of arms 1
4 is supported by the column 12 via the actuator section 16. In addition, by moving the pair of arms 14 so as to approach each other by the actuator unit 16,
It is sandwiched between two three-axis contact sensor arrays 18.

As shown in FIG. 2, the three-axis contact sensor array 18 has a predetermined shape, for example, a finger-shaped organic material 24, and is arranged in a matrix on the organic material 24 corresponding to the shape of the organic material 24. A plurality of three-axis contact sensors 22
And a wiring board 26 on which wiring connected to each of the plurality of contact sensors 22 is disposed and which is disposed between the organic material 24 and the plurality of triaxial contact sensors 22.

As shown in FIGS. 3 and 4, the triaxial contact sensor 22 includes a plurality of (four in the present embodiment) piezoelectric elements 30 fixed to a base 38 and a plurality of piezoelectric elements 30. A contact portion 28 provided so as to cover and having a convex spherical upper portion and contacting the contacted object 20, an electrode 36 disposed at the center of the surface of the plurality of piezoelectric elements 30 on the base 38 side, and The electrode 3 arranged at the center of the surface on the contact portion 28 side
4. Since the upper portion of the contact portion 28 has a convex spherical surface, the contact portion 28 makes point contact with the contacted object 20.

The base 38 is fixed to the wiring board 26 and has four through holes 32 at positions corresponding to the centers of the four piezoelectric elements 30 (see FIG. 4). Two through holes 33 are provided. An electrode 36 is arranged at the tip of the through hole 32 on the side of the piezoelectric element 30. Line W1 having one end connected to electrode 36
Are disposed on the wiring board 26 through the through holes 32, and the other end is a switching element 44 (see also FIG. 5).
It is connected to the. Line W2 having one end connected to electrode 34
Is disposed on the wiring board 26 through the through hole 33 in the contact portion 28, and the other end is connected to the switching element 44.
It is connected to the.

As shown in FIG. 5, the contact sensor device is provided with predetermined data (surface shape data of the object 20 to be described later).
And a microcomputer 40 to which the above-described actuator unit 16 is connected. The microcomputer 40 includes a CPU (not shown), a ROM, a RAM, input / output ports, and a bus connecting these.

The input / output ports of the microcomputer 40 include a keyboard 42, an actuator unit 16, and a switching S
The W element 44 is connected. Switching SW element 4
4, the electrode 34 and the electrode 36 and the power supply circuit 46 are connected. The switching SW element 44 alternately changes the direction of the voltage from the power supply circuit 46 in accordance with a control signal from the microcomputer 40 and applies the direction to the electrode 34 and the electrode 36. Further, the voltage generated in the piezoelectric element 30 is input to the microcomputer 40. Therefore, the switching SW element 44 and the microcomputer 40 are connected by the control signal line and the voltage line. A variable resistor R is connected between the switching element 44 and a power supply line from the power supply circuit 46. When the variable resistor is controlled by a control signal from the microcomputer 40, the magnitude of the voltage applied to the electrodes 34 and 36 is changed.

FIG. 6 shows a holding processing routine executed by the microcomputer 40 when a holding start button (not shown) of the keyboard 42 is turned on.

When this routine starts, step 5
In 2, the three-axis contact sensor array 18 determines whether or not the surface shape data of the object to be pinched at the contact portion has been input via the keyboard 42.

When the surface shape data of the object to be held is input, in step 54, the surface shape of the object to be held
A voltage is applied to each three-axis contact sensor 22 so that the surface of the axis contact sensor array 18 corresponds.

That is, the piezoelectric element 30 has a property that its thickness changes according to the direction and magnitude of the voltage applied via the electrodes 34 and 36. For example, the switching element 44
When the voltage is applied such that the electrode 34 is positive and the electrode 36 is negative, the thickness of the piezoelectric element 30 is increased, the electrode 34 is negative, and the electrode 36 is positive. When a voltage is applied, the piezoelectric element 3
0 becomes narrower. The amount by which the thickness of the piezoelectric element 30 increases and decreases is determined by the magnitude of the applied voltage. Accordingly, the direction and magnitude of the voltage applied to the electrodes 34 and 36 are changed by controlling the switching element SW44 and the variable resistor R, and the thickness of the piezoelectric element 30 is set to a desired thickness. Accordingly, the posture of the contact portion 28 becomes a desired posture, and corresponds to the surface shape of the held object 20 as a whole.

In the example of FIG. 1, the three-axis contact sensor array 18
The direction and magnitude of the voltage are set such that the thickness of the triaxial contact sensor 18 located in the central portion of the Control.

In step 56, the actuator unit 16 is controlled to hold the held object 20. As a result, the contact portion 28 comes into contact with the held object 20 and the contacted object 20
Receive power from. As described above, when a force is received from the contacted object 20, a voltage having a magnitude corresponding to the amount of the received force is generated in the piezoelectric element 30 and input to the microcomputer 40 via the electrodes 34 and 36. .

In step 58, the voltage of each triaxial contact sensor is fetched, and in step 60, the force received by each triaxial contact sensor is calculated from the fetched voltage.

That is, as shown in FIG.
On the other hand, a plane parallel to the wiring board
A plane perpendicular to the plane is defined as a YZ plane and a ZX plane.
When the coordinates of the X axis, Y axis, and Z axis are set in
Axis, Z axis direction force F_X, F_Y, F _ZIs, for example, (1)
It is obtained from Equations (3) to (3).

[0027]

[Number 1] _{F X = C X {(V1} + V4) - (V2 + V3)} ··· (1)

[0028]

F _Y = C _Y {(V1 + V2) − (V3 + V4)} (2)

[0029]

(Equation 3) F_Z= C_Z(V1 + V2 + V3 + V4) (3) where V1, V2, V3, and V4 are the four piezoelectric elements 30
Is the output voltage of C _X, C_Y, C_ZIs a coefficient.

In step 62, the calculated force F _X ,
The clamping force is corrected based on F _Y and F _Z.

As described above, in the present embodiment, the contact sensor is provided with the piezoelectric element, and the piezoelectric element is hard and small in nature. Compared to sensors, contact sensors can be made more difficult to break, and compared to light detection type contact sensors, light sources, cameras, etc. are unnecessary, so
The contact sensor can be downsized.

Further, in the above-described embodiment, since the posture of the contact portion can be set to a desired posture, a multifunctional contact sensor device can be obtained. In particular, it can be a sensory feedback in virtual reality or the like, that is, a key technology of a touch display.

Further, in the above-described embodiment, since the contact portion has a convex spherical surface and is in point contact with the contacted object,
The horizontal force can be easily detected.

The shape of the contacted object is merely an example, and the posture of the contact portion may be changed so as to correspond to various shapes of the contacted object.

In the above-described embodiment, the three-axis contact sensor is configured by arranging four piezoelectric elements. However, the present invention is not limited to this.
One, two, three, five, etc. may be provided.

[0036]

As described above, the present invention is provided with a piezoelectric element, and since the piezoelectric element is hard and small in nature, it is possible to reduce the size and size of the contact sensor. Have.

Further, the present invention has an effect that the posture of the contact portion can be set to a desired posture, so that a multifunctional contact sensor device can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a part of a holding robot.

FIG. 2 is a perspective view of a three-axis contact sensor array.

FIG. 3 is a sectional view of a three-axis contact sensor.

FIG. 4 is an exploded view showing a relationship between a piezoelectric element and an electrode in the three-axis contact sensor.

FIG. 5 is a block diagram of a control system of the three-axis contact sensor device.

FIG. 6 is a flowchart showing a clamping process routine of the three-axis contact sensor device.

FIG. 7 is an explanatory diagram illustrating a method of calculating a force received by a three-axis contact sensor.

[Explanation of symbols]

 22 triaxial contact sensor 28 contact part 30 piezoelectric element 34, 36 electrode 40 microcomputer 44 switching SW element 46 power supply circuit

Claims (2)

[Claims] 1. A contact sensor comprising: at least one piezoelectric element fixed on a base; a contact portion provided to cover the piezoelectric element; and an electrode disposed on the piezoelectric element. 2. The contact sensor according to claim 1, a voltage detecting means for detecting a voltage generated at the electrode, an applying means for applying a voltage to the electrode, and the applying means such that a posture of the contact portion is changed. And a control means for controlling the voltage applied by the contact sensor device.