JPS58205830A - Thin force sensor - Google Patents

Abstract

PURPOSE:To obtain an appropriate sensitivity to force and moment in any direction pertaining to a force sensor for detecting external force mounted on the wrist of a robbot by arranging a plurality of arms extending radially from the center in a construction of bending beam. CONSTITUTION:The body of a force sensor has a base plate 10 cut out of a disc in a shape of a human hand. A strain gage 17 is applied somewhere on the six cantilever beams 11-16 as a part of the base plate 10 to detect a distortion caused in any of the centilever beams. With such an arrangement, the force sensor made thinner enables effective utilization of working space when mounted on the wrist of a robot and can provide an even sensitivity to a 6-axis stress.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a force sensor. For more information, see the force sensor attached to the robot's wrist and used to detect external force or reaction force applied to a tool or band. Regarding the conventional force sensor, Figures 1 and 2 show the structure of the Draver Institute's force sensor. The force sensor has two rings (1) as shown in the figure.
, (2) are connected by three pillars (3), (4), (
Attach the strain gauge (6) to 5) and measure the strain (elongation,
It has a structure that detects shrinkage, torsion (1 bending) and calculates the force acting between two circular rings due to twisting (6 types of compression, tension, 9 bending, and torsion, etc.).

However, the force sensor with this structure needs to be thick enough to correspond to the height of the three pillars, so it has to be thick as a whole, and the above six types of force (hereinafter referred to as Fx
+ Fy + Fz + Txa Tyl Tz)), and had the disadvantage that it was not possible to measure all six types of force with high accuracy. This drawback is due to the fact that since three columns are used as detection members, the bending rigidity of the columns is significantly lower than the stretching and shrinking rigidity.

Therefore, the present invention minimizes the overall thickness, makes it possible to be attached to the wrist of a robot, etc., has appropriate sensitivity to forces and moments in all directions as the object of measurement, and The purpose is to provide a force sensor with a simple structure.

That is, the present invention has a plurality of force detection arms extending radially from the center, the arms having a curved structure, and
The force sensor is characterized by having a strain gauge in the middle of the arm to detect the deflection of the arm.

Next, the configuration of the present invention will be further explained in a supplementary manner.

As a method to solve the imbalance in sensitivity, which is a drawback of the conventional technology, the present invention eliminates the conventional use of elongation, shrinkage, and bending of columns for detection, and instead detects only one bend.
It detects forces in all directions just by bending.

In addition, the term "curved" as used in the present invention refers to a mode in which the arm is bent in the middle or forms an arc.Also, in order to make a thin force sensor, it is made of a single plate structure. Even in a single-plate structure, it is common to have legs radially in order to be able to detect forces in the X + 3' + Z axis directions and moments around those axes, and to have appropriate detection sensitivity in the above structure. It has a bent structure or a curvature structure, that is, a curved structure.

Next, the present invention will be explained based on illustrated embodiments.

FIG. 6 is a plan view showing the overall appearance of the force sensor of the present invention. Six cantilever beams (11) ~
A strain gauge (17) is attached to the middle of (16) to detect strain occurring in the cantilever beam. Next, the manner of use of the force sensor of the present invention will be explained with reference to FIG. As shown in Figure 4 (a), the cantilever beam (12).

The tips of (14) and (16) are fixed to the robot's wrist (18), and the tips of cantilever beams (11), (13), and (15) are fixed to the reel (19). The coordinate system is the fourth
0 defined as shown in Figure (b). Figure 5 (a) also shows an enlarged view of one of the cantilever beams (11). The strain gauge on the cantilever beam is A in the same figure (b).
As shown in the arrow view and the B arrow view in (c), (111) is on the top surface, (112) is on the bottom surface, (113), (11
4) is pasted on the side.

Next, the principle of the force sensor of the present invention will be explained. In FIG. 4, when the tool (19) exerts a force on the robot wrist (18) in the Z direction, the cantilever beams (11), (13), and (15) move in the Z direction in FIG.
bent in the positive direction of cantilever beams (10), (12
).

(14) is bent in the negative direction of Z, so the strain detected by the strain gauge is δ(i) (where i is the number of the strain gauge in the diagram, and the numbering method is as shown in Figure 5). 2
The digit is the number of the cantilever beam, the lower one digit 1 is the top surface, 2 is the bottom surface, 3 is the O side of each beam when viewed from the 2 ■ side, and 4 is the ■ side), then when the external force is F2 Fz can be detected using the following formula. Similarly, Tx and Ty can also be detected. Similarly, by using the strain gauge attached to the side, FXI
FXI Tz (moment around the Z-axis) can be detected 0 Therefore, according to the force sensor of the present invention, the thin shape allows it to be attached to the wrist of a robot. The 4-way work space can be used effectively, and the 6-axis response/4/force (FXI Fy I Fz I TX I TyI
It was possible to provide a force sensor that can obtain average sensitivity with respect to TZ) and has a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional example, FIG. 2 is a front view showing a conventional example, FIGS. 3 to 5 show an embodiment of the present invention, and FIG.
The figure is a plan view showing the overall appearance of the force sensor of the present invention.
FIG. 4(a) is a side view showing how the sensor of the present invention is used;
Figure 4 (B) is an explanatory diagram showing the coordinate system in Figure 4 (A), Figure 5 (A) is a plan view of the main part of the sensor of the present invention, and Figure 5 (B) is Figure 5 (A). FIG. 5H is a view taken along arrow A in FIG. 5, and FIG. 5H is a view taken along arrow B in FIG. 10...Force sensor 11, 12.1! l, 14.15.16...Curved bar 17...Strain gauge flower, 5 figure 1b punishment 4 figure de 5 figure] 8

Claims (1)

[Claims] A thin type device having a plurality of arms for detecting force extending radially from the center, each arm having a curved structure and further having a strain gauge in the middle of the arm for detecting the deflection of the arm. Force sensor.