JPH04304988A - Device for fingertip pressure sensor - Google Patents

Abstract

PURPOSE:To promptly and accurately detect the contact pressure between a robot and an object. CONSTITUTION:A cavity 15 having an opening 15a at its end is formed within an elastic cap 14 and filled with a non-compressive fluid. A pressure sensor 16 is inserted in the opening 17a of the cavity 15 and the elastic cap 14 and the pressure sensor 16 are held by a holding member 18. The holding member 18 is mounted on the finger 1 of a robot hand in such a manner as freely oscillating via a joint portion 2. When an object makes contact with the elastic cap 14, this contact pressure is detected by the pressure sensor 16 via the non- compressive fluid.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art Conventionally, research has been conducted on methods for stably grasping an object and manipulating it to perform a desired task using a robot hand having a plurality of fingers. Such gripping work requires a fingertip pressure sensor that detects the contact force and contact state between each fingertip and the object.

Conventionally, this type of fingertip pressure-sensitive 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, accurate measurement values cannot be obtained between pressure-sensitive element points, so it is necessary to arrange more pressure-sensitive elements at the fingertips of the robot hand to increase the density.

However, when a large number of pressure-sensitive elements are arranged at the fingertips of a robot hand, problems arise in miniaturizing the robot hand, and the processing of signal lines for pressure detection becomes complicated.
There are problems such as difficulty in forming the fingertip into a desired shape.

[0005] Furthermore, each finger joint of a robot hand is generally driven by a wire using a motor installed at a distance from the joint, without incorporating an actuator into each joint. It needs to be routed in a complicated manner. In this case, it is also possible to measure the contact force from the tension of the wire on the motor side. However, in the joint drive wire on the distal end side, frictional force may act on the wire while it is being routed, and there is a drawback that even if the motor side attempts to measure the contact force from the tension of the wire, it cannot be measured accurately.

[0006] Furthermore, in order to solve the above-mentioned problem, a fingertip sensing device is developed in which a cavity provided in the fingertip cap and a pressure detector that detects pressure changes in the cavity due to force applied to the outer surface of the cap are connected via a tube. A pressure sensor has been developed. This pressure detector is placed in a position where it does not interfere with the movement of the robot hand. However, when installing or replacing the fingertip pressure sensor, it is troublesome to route the tube, and because the fingertip cap and pressure sensor are separated by the length of the tube, the response speed when detecting contact force is slow. There was a problem. In addition, when an object comes into contact with the edge of the cavity, the output from the pressure sensor decreases, and the output from the pressure sensor is affected by the contact position on the outer surface. There has been a problem in that when the upper contact position changes significantly, the contact force cannot be detected with high accuracy.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a fingertip pressure-sensitive sensor for a robot hand that can accurately detect the contact pressure of the fingertips of a robot hand with a fast response speed. With the goal.

[0008]

[Means for Solving the Problems] The present invention provides an elastic cap having a cavity opened at the proximal end side and filled with an incompressible fluid, and an elastic cap that is inserted into the opening of the cavity and detects fluid pressure. The present invention is a fingertip pressure sensor device characterized by comprising: a pressure sensor that holds the elastic cap and the pressure sensor, and a holding member that holds the elastic cap and the pressure sensor and attaches it to a finger of a robot hand.

[0009]

[Operation] When grasping an object with the robot hand,
When the object contacts the elastic cap, this contact pressure increases the pressure of the fluid within the cavity. The increase in fluid pressure is detected by a pressure detector inserted into the opening of the cavity.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 8 are diagrams showing an embodiment of a robot fingertip pressure-sensitive sensor according to the present invention.

First, the entire fingertip pressure sensor will be explained with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, a fingertip pressure sensor 10 is equipped with an elastic cap 1 made of an elastic material that easily conforms to a contact object, such as silicone rubber.
It is equipped with 4. This elastic cap 14 is attached to the holding cylindrical portion 1
It is held by a holding member 18 having 9. At the same time, the holding member 18 holds the pressure detector 16 on the side opposite to the elastic cap 14, and this 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 explained in detail. The elastic cap 14 has an approximately elliptical shape with an outer shape approximately similar to that of a human fingertip. This elastic cap 14 has an inner cylindrical portion 1 on its inside as shown in FIGS. 3 and 4.
It has 7 integrally.

[0013] The elastic cap 14 is attached to an object (not shown).
The object 14 is gripped by contacting with the contact surface 14a. A cavity 15 is formed inside the elastic cap 14 and filled with an incompressible fluid, such as castor oil. This cavity 15 includes at least the contact surface 14a
The cavity 15 is formed along substantially the entire area, and further extends into the inner cylindrical part 17 and opens at an opening 17a of the inner cylindrical part 17.

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

The elastic cap 14 has a proximal end (opening 14
The elastic cap 14 has an axis extending from side a) toward the distal end, and the outer shape of the elastic cap 14 in a cross section perpendicular to this axis is approximately oval. Further, the outer shape of the elastic cap 14 in a cross section perpendicular to the axis gradually becomes smaller from the proximal end toward the distal end (FIGS. 6 to 8).

On the other hand, the holding member 18 consists of a distal end 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 . Further, the base end side holding member 18b is the pressure detector 1.
6, and is attached to the finger 1 of the robot hand via a joint 2 so as to be swingable.

The pressure detector 16 has a cylindrical detection portion 16a, which is inserted into an opening 17a of the inner cylindrical portion 17 and configured to detect the fluid pressure within the cavity 15. It has become. The pressure detector 16 includes, for example, a diaphragm type semiconductor pressure sensor (not shown). The output from this semiconductor pressure sensor is amplified by an amplifier and output as a voltage signal.

Next, the operation of this embodiment having such a configuration will be explained.

First, in the grasping action of the robot hand,
The contact surface 14a of the elastic cap 14 contacts the object,
Grasp 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. The rise in pressure of the fluid within the cavity 15 is detected by a semiconductor sensor within the pressure detector 16, and the output from the semiconductor sensor is amplified by an amplifier and output as a voltage signal.

According to this embodiment, the outer shape of the elastic cap 14 is approximately oval in the cross section perpendicular to the axis, and the cross-sectional shape gradually becomes smaller from the proximal end to the distal end. Therefore, the object can be easily grasped. In addition, 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 elastic cap 14 reliably and accurately provides elasticity no matter which part of the contact surface 14a the object comes into contact with. Contact pressure applied to the cap 14 can be detected. Furthermore, since the pressure detector 16 is directly inserted into the opening 17a of the cavity 15, it is possible to reliably and quickly detect a rise in the pressure of the fluid within the cavity 15. In addition, since the elastic cap 14 and the pressure detector 16 are held together by the holding member 18, they can be replaced as a unit from the finger 1 of the robot hand 1.
Easy to replace.

[0021]

[Effects of the Invention] As explained above, according to the present invention,
When the fluid pressure inside the cavity increases due to the contact pressure applied to the elastic cap from the object, this increase in fluid pressure is directly detected by the pressure detector inserted into the opening of the cavity, so it can be quickly and reliably detected. Contact pressure can be detected. Furthermore, since the elastic cap and the pressure sensor are integrally held by the holding member, they can be replaced as one unit from the finger of the robot hand, making the replacement work easy.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view showing an 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 cross-sectional view of the fingertip pressure sensor device shown in FIG. 1;

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

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

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

FIG. 7 is a diagram showing a cross-sectional B shape of the elastic cap shown in FIG. 5;

8 is a diagram showing a C-shaped cross section of the elastic cap shown in FIG. 5. FIG.

[Explanation of symbols]

1. Robot hand fingers 2 Joints 10 Fingertip pressure sensor 14 Elastic cap 15 Cavity 16 Pressure detector 18 Holding member

Claims (3)

[Claims] 1. An elastic cap having a cavity that is open at the proximal end and filled with an incompressible fluid; a pressure detector that is inserted into the opening of the cavity and detects fluid pressure; A fingertip pressure sensor device comprising: a cap; and a holding member that holds the pressure sensor and attaches it to a finger of a robot hand. 2. The elastic cap according to claim 1, wherein the elastic cap has an axis extending from the proximal end to the distal end, and the outer shape is oval in a cross section perpendicular to the axis. Fingertip pressure sensor device. 3. The fingertip pressure sensor device according to claim 2, wherein the outer shape of the elastic cap in a cross section perpendicular to the axis thereof gradually becomes smaller from the proximal end toward the distal end.