JPS6288590A - Robot hand - 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 [Special Field of Application] The present invention relates to a robot node capable of detecting the contact force or clamping force between a grasping claw and an object to be grasped, in a robot that performs various tasks.

[Conventional technology]

In order to grip an object reliably and with high precision in various operations performed by a robot, it is necessary to detect the acting force between the gripping claw and the object to be gripped.

Conventionally, a method using a strain gauge as shown in FIG. 3 is known as a method for detecting the acting force applied to the gripping claws. In FIG. 3, numerals 1 and 2 are gripping claws, 3a and 3b are strain gauges affixed to the gripping claw 1, 4a and 4b are strain gauges affixed to the gripping claw 2, and 5 is an object to be gripped.

The clamping force or contact force between the gripped object 5 and the gripping claws 1 and 2 is expressed as strain in the gripping claws 1 and 2, which are elastic members, by strain gauges 3a, 3b, and 4a, respectively.

4b is detected as a resistance change.

[Problem that the invention seeks to solve]

The conventional detection method using strain gauges described above has the advantage of high sensitivity and increased rigidity, but since the strain gauges are attached with adhesive, the adhesive strength decreases as time passes, causing the strain gauges to lift or peel off. Therefore, it cannot withstand long-term use. ■Does the adhesive deteriorate even more severely in liquids such as water or oil? In addition, it is difficult to apply because the strain gauge part is difficult to seal, ■The strain gauge itself is sensitive to temperature changes, so the detection accuracy is poor for use over a wide temperature range. was there.

The purpose of the present invention is to solve the problem of deterioration over time and the influence of the usage environment of the gripping force detection part of a robot hand, and to provide a gripping device that can operate stably over a long period of time and can be used in liquids such as water and oil. The objective is to provide a robot hand that detects force.

[Means for solving problems]

The present invention fixes the end of a displacement detection plate to an elastically displaceable gripping claw, and fixes a displacement detector to the gripping claw to detect displacement of the free end of the displacement detection plate in a non-contact state. It is characterized by:

[Embodiment II] FIG. 1 is a diagram illustrating a first embodiment of the present invention,
6 is a gripping claw, 6a is a notch, 7 is a buffer member, 8 is an object to be gripped, 9 is a spacer, 10 is a displacement detection plate, 11 is a displacement detector, 11a is a lead wire, 12 is a displacement detector holder, Reference numeral 13 denotes a gripping pawl drive screw, 14 a direct guide guide for the gripping pawl, and 15 a linear guide bearing.

The gripping claws 6 have a structure in which they can be elastically displaced by providing a notch 6a at a position midway between the gripping point of the object to be gripped 8 and the base end. In this case, the amount of displacement with respect to the contact force F and the size of the deflection angle of the tip of the gripping claw 6 are determined by the notch 6
It can be set freely depending on the position and dimensions of a. The displacement detection plate 10 has one end protruding toward the proximal end of the gripping claw 6, and the other end attached to the tip of the gripping claw 6 with a spacer 9.
It is fixed with screws 16 via. Displacement detector 1
Reference numeral 1 detects the displacement U of one end (free end) of the displacement detection plate 10 in a non-contact state, and the base end side of the gripping claw 6 is positioned opposite to the one end of the displacement detection plate 10. is fixed. In this case, a holder 12 is fixed to the base end of the gripping claw 6 with a screw 17. and displacement detector 1
1 is inserted into the hole 18 formed in the holder 12,
It is fixed to the holder 12 by tightening a nut 19 to a threaded portion formed on its outer circumferential surface.

As the displacement detector 11, an eddy current displacement detector, a capacitance displacement detector, or an optical displacement detector tube is used. The output of this displacement detector 11 is supplied to a displacement detection circuit (not shown) via a lead wire 11a.

Next, the operation of this embodiment will be explained.

The gripping claw 6 moves along the gripping claw linear guide 14 by the gripping claw drive screw 13, approaches and contacts the object to be grasped 8 via the buffer member 7 provided at its tip, and as shown in the figure. It is pressed by the gripping force F. The notch portion 6a of the gripping claw 6 is elastically deformed by the action of the gripping force F, and the tip of the gripping claw 6 is displaced in the direction of the gripping force F and is also displaced to a deflection angle. The displacement detection plate 10 also tilts to the deflection angle, and the displacement between the free end of the displacement detection plate 10 and the displacement detector 11 changes, and as a result, the gripping force F can be detected as the displacement U.

According to the mechanics of materials, the displacement U is expressed as
*Month/6th day......10 can be earned. In this case 1, b* = b/
, , a* = a/, where are the dimensions of the portion shown in FIG.
This is the moment of inertia of a.

According to equation (1), the gripping force F and the displacement U are expressed linearly, and therefore the gripping force F can be easily determined from the value of the displacement detector. In addition, according to this robot/.nd, the displacement of the contact point can be magnified and detected. For example, when a = 0, the displacement of the contact point of the tip of the gripping claw 6 is FA"/3E
r, and if b=51, the detection unit is magnified five times, so the gripping force can be detected with high accuracy.

Here, if an eddy current type displacement detector 11 is used, for example, it is possible to obtain a resolution of about 1 μm without contact, and it is also possible to obtain a resolution of about 1 μm in water or oil. , and products with small temperature coefficients (
For example, 0.1% of full scale per 1°C) can be easily determined, ensuring extremely long-term reliability, and stably detecting gripping force in liquids and in environments with a relatively wide temperature range. It is possible to construct a robot hand that can do this.

The embodiment of the present invention shown in FIG. 1 has a predetermined gripping contact point, and is particularly effective when there is only a slight variation in the contact position and can be detected very accurately.

FIG. 2 is a diagram showing another embodiment of the invention.

This embodiment takes into consideration the case where the contact position of the gripping claw 6 with the object to be gripped 8 fluctuates rapidly.

In the second embodiment shown in FIG. 2, the cutout portion 6a responsible for elastic deformation of the gripping claw 6 has a parallel spring structure. With this structure, the contact position fi between the object to be gripped 8 and the gripping claws 6 is
Even if a changes, the amount of displacement U between the free end of the displacement detection plate 10 and the displacement detector 110 with respect to the contact force F is hardly affected. Therefore, even if the shape of the object to be gripped 8 changes, the contact force or the clamping force can be accurately detected. 4° Also, in this embodiment, even when it is necessary to accurately hold the object 8 between parallel planes, the gripping force F
Even if this action is applied, the tip of the gripping claw 6 is only displaced in parallel, and almost no bending angle occurs, so this is an extremely effective means.

〔Effect of the invention〕

According to the present invention, the displacement detection plate and the displacement detector can be fixed to the gripping claw with screws or the like in a manner that cannot be peeled off, so that peeling does not occur unlike in the conventional method of pasting strain gauges, resulting in long-term reliability. In addition, displacement detectors that can be used in liquids such as water and oil and are less affected by temperature can be easily adapted to work in liquids and under a relatively wide range of temperature conditions. Therefore, the present invention can be applied to remote control robots for inspection and maintenance that require long maintenance periods, construction work robots that are exposed to water and oil, and robots for offshore development. There are advantages such as being able to improve the performance of these robots.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the invention, FIG. 2 is a sectional view showing a second embodiment of the invention, and FIG. 3 is a perspective view of a conventional robot hand. 6...Gripping claw, 8...Gripped object, 1
0... Displacement detection plate, 11... Displacement detector.

Claims (1)

[Claims] Displacement detection robot hand that grips and manipulates objects with elastically displaceable gripping claws, in which one end protrudes toward the proximal end of the gripping claw and the other end is fixed to the tip of the gripping claw. What is claimed is: 1. A robot hand comprising: a holding plate; and a displacement detector fixed to the proximal end side of the gripping claw and detecting displacement of one end of the displacement detecting plate in a non-contact state.