JP3183465B2 - Fingertip pressure sensor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingertip pressure sensor for a robot which is attached to a fingertip of a robot hand.

[0002]

2. Description of the Related Art Hitherto, research has been conducted on a method of stably gripping an object by a robot hand having a plurality of fingers and manipulating a target operation. Such a gripping operation requires a fingertip pressure sensor for detecting a contact force and a contact state between each fingertip and the object.

Conventionally, this type of fingertip pressure sensor has been developed and prototyped as a tactile sensor, but most of them have a complicated structure in which a large number of pressure-sensitive elements are arranged in a matrix at the fingertip of a robot hand. . In the case of such a fingertip pressure-sensitive sensor, an accurate measurement value cannot be obtained between the pressure-sensitive element points. Therefore, it is necessary to arrange more pressure-sensitive elements at the fingertip of the robot hand to increase the density.

However, when a large number of pressure-sensitive elements are arranged at the fingertip of the robot hand, a problem arises in downsizing of the robot hand, which complicates processing of signal lines for pressure detection,
There is a problem that it is difficult to form a fingertip into a desired shape.

[0005] In general, the finger joints of the robot hand are driven by wires using a motor provided at a position away from the joints without incorporating an actuator in each joint. It needs to be routed in a complicated manner. In this case, it is conceivable to measure the contact force from the wire tension on the motor side. However, in the joint drive wire on the distal end side, a frictional force may be applied to the wire while the wire is being routed, and there is a drawback that accurate measurement is not possible even if an attempt is made to measure the contact force from the wire tension on the motor side.

In order to solve the above-mentioned problem, a cavity provided in a fingertip cap and a pressure detector for detecting a pressure change in the cavity due to a force applied to the outer surface of the cap are connected via a tube. Pressure sensors have been developed. This pressure detector is arranged at a position where it does not hinder the movement of the robot hand. However, when the fingertip pressure sensor is installed or replaced, the tubing is troublesome or the fingertip cap and the pressure detector are separated by the length of the tube, so the response speed when detecting the contact force is slow. There was a problem of becoming. Also, when an object comes into contact with the vicinity of the end of the cavity, the output from the pressure detector will decrease, or the output from the pressure detector will be affected by the contact position on the outer surface. In the case where the upper contact position changes significantly, there is a problem that the contact force cannot be detected with high accuracy.

The present invention has been made in view of the above points, and provides a fingertip pressure sensor of a robot hand which can accurately detect the contact pressure of the fingertip of the robot hand at a high response speed. With the goal.

[0008]

According to the present invention, there is provided an elastic cap having a cavity which is open at the base end and which is filled with an incompressible fluid, and which is inserted into the opening of the cavity and detects fluid pressure. A pressure detector, and a holding member that holds the elastic cap and the pressure detector and attaches to the finger of the robot hand, wherein the holding member has a holding cylindrical portion extending into the cap, and inside the elastic cap. ,
A finger tip, characterized by providing a cavity formed between the contact surface of the elastic cap and the holding cylinder and along the outer periphery of the contact surface, the cavity extending inside the holding cylinder and communicating with the pressure detector. It is a pressure-sensitive sensor device.

[0009]

According to the present invention, the cavity formed inside the elastic cap is formed along the outer periphery of the contact surface between the contact surface of the elastic cap and the holding cylindrical portion extending into the elastic cap. Therefore, the cavity can be held by the holding cylindrical portion extending into the elastic cap. Further, the cavity extends inside the holding cylinder and communicates with the pressure detector. For this reason, even if an excessive force is applied to the elastic cap, the cavity is not greatly deformed or the force does not escape, and the contact pressure can be detected accurately with a quick response.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 8 are views showing an embodiment of a fingertip pressure sensor of a robot according to the present invention.

First, the whole fingertip pressure sensor will be described with reference to FIGS. As shown in FIGS. 1 and 2, the fingertip pressure-sensitive sensor 10 includes an elastic cap 14 made of an elastic material that is easily adaptable to a contact target such as silicon rubber. The elastic cap 14 is held by a holding member 18 having a holding cylindrical portion 19. At the same time, the holding member 18 holds the pressure detector 16 on the side opposite to the elastic cap 14, and the holding member 18 is swingably attached to the finger 1 of the robot hand via the joint 2.

Next, the fingertip pressure sensor 10 will be described in detail. The elastic cap 14 has a substantially cylindrical shape having an outer shape substantially similar to that of a human fingertip. The elastic cap 14 has an inner cylindrical portion 1 inside thereof as shown in FIGS.
7 are integrally provided.

The elastic cap 14 is provided for an object (not shown).
And the contact surface 14a, and grips the object 14. Inside the elastic cap 14, a cavity 15 filled with an incompressible fluid, for example, castor oil, is formed. This cavity 15 has at least a contact surface 14a.
It is formed along substantially the entire area, and the cavity 15 extends into the inner cylindrical portion 17 and opens at the opening 17 a of the inner cylindrical portion 17.

The elastic cap 14 will be further described with reference to FIGS. Here, FIG. 6 shows a cross-sectional shape of the elastic cap of FIG. 5, FIG. 7 shows a cross-sectional shape of the elastic cap of FIG. 5, and FIG. 8 shows a cross-sectional shape of the elastic cap of FIG.

The elastic cap 14 is provided at the base end (opening 14).
The elastic cap 14 has an axis extending from the side a) to the distal end, and the outer shape of the elastic cap 14 in a cross section perpendicular to the axis is substantially elliptical. Further, the outer shape of the elastic cap 14 in a cross section perpendicular to the axis gradually decreases from the base end to the tip end (FIGS. 6 to 8).

On the other hand, the holding member 18 comprises a distal holding member 18a having a holding cylindrical portion 19 and a proximal holding member 18b. The holding cylindrical portion 19 is inserted into a space 20 formed on the outer periphery of the inner cylindrical portion 17 and holds the elastic cap 14 in close contact with the inner peripheral surface of the elastic cap 14. In addition, the base end side holding member 18b is a pressure detector 1
6 and is swingably attached to the finger 1 of the robot hand via the joint 2.

The pressure detector 16 has a cylindrical detecting portion 16a. The detecting portion 16a is inserted into the opening 17a of the inner cylindrical portion 17 so as to detect the fluid pressure in the cavity 15. Has become. The pressure detector 16 incorporates, for example, a diaphragm type semiconductor pressure sensor (not shown). The output from the semiconductor pressure sensor is amplified by an amplifier and output as a voltage signal.

Next, the operation of this embodiment having the above-described configuration will be described.

First, in the gripping operation of the robot hand,
The contact surface 14a of the elastic cap 14 comes into contact with the object,
Hold the object. In this case, the pressure of the fluid in the cavity 15 increases due to the contact pressure applied to the contact surface 14a from the object side. Then, the pressure increase of the fluid in the cavity 15 is detected by the semiconductor sensor in the pressure detector 16, and the output from the semiconductor sensor is amplified by the amplifier and output as a voltage signal.

According to this embodiment, the outer shape of the elastic cap 14 is substantially elliptical in a cross section perpendicular to the axis, and the cross sectional shape is gradually reduced from the base end to the tip end. Therefore, the object can be easily grasped. Also, since the cavity 15 of the elastic cap 14 is formed along substantially the entire area of the contact surface 14a with the object,
The contact pressure applied to the elastic cap 14 can be reliably and accurately detected regardless of which part of the contact surface 14a is in contact with the object. Further, since the pressure detector 16 is directly inserted into the opening 17a of the cavity 15,
The pressure rise of the fluid in the inside can be detected reliably and quickly. The elastic cap 14 and the pressure detector 16
Since it is integrally held by the holding member 18, it can be exchanged and exchanged integrally from the finger 1 of the robot hand 1, which facilitates the exchange.

[0021]

Thus, according to the present invention, the cavity formed inside the elastic cap is formed between the contact surface of the elastic cap and the holding cylindrical portion extending into the elastic cap and along the outer periphery of the contact surface. The cavity can be held by the holding cylindrical portion extending into the elastic cap. Further, the cavity extends within the holding member and communicates with the pressure detector. For this reason, even if an excessive force is applied to the elastic cap, the cavity is not greatly deformed and the force does not escape. In this way, since the cavity is not greatly deformed or the force does not escape, the contact pressure applied to the elastic cap can be accurately transmitted to the pressure detector by the incompressible fluid in the cavity extending into the holding cylindrical portion, and therefore, The contact pressure applied to the elastic cap can be quickly, reliably, and accurately detected.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing one embodiment of a fingertip pressure sensor device according to the present invention.

FIG. 2 is an exploded perspective view of the fingertip pressure sensor device shown in FIG. 1;

FIG. 3 is a vertical sectional view of the fingertip pressure-sensitive sensor device shown in FIG. 1;

FIG. 4 is a horizontal sectional view of the fingertip pressure-sensitive sensor device shown in FIG. 1;

FIG. 5 is a perspective view showing an outer shape of an elastic cap.

FIG. 6 is a diagram showing a cross-sectional A shape of the elastic cap shown in FIG. 5;

FIG. 7 is a view showing a cross section B of the elastic cap shown in FIG. 5;

FIG. 8 is a view showing a cross-sectional C shape of the elastic cap shown in FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 finger of robot hand 2 joint 10 finger pressure sensor 14 elastic cap 15 cavity 16 pressure detector 18 holding member

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-152786 (JP, A) JP-A-60-16393 (JP, A) JP-A-48-94152 (JP, A) JP-A-61- 203287 (JP, A) JP-A-62-123986 (JP, A) JP-A-57-144687 (JP, A) JP-A-48-49156 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B25J 15/08

Claims (1)

(57) [Claims] An elastic cap having a first cavity adjacent to the contact surface and having a contact surface in contact with the outside, and a cylindrical second cavity connected to the first cavity. a front SL connected pressure detector in the second cavity, covering the second cavity, for holding said elastic cap coercive
A holding member that holds the pressure detector and is attached to a finger of a robot hand; the first and second cavities are filled with an incompressible fluid; The first cavity portion is located between the contact surface and the holding cylinder portion, and the pressure of the incompressible fluid in the first cavity portion increases due to the contact pressure applied to the contact surface. A fingertip pressure-sensitive sensor device, wherein the pressure detector detects the pressure through two cavities.