JPH01156632A - Multi component force sensor - Google Patents

Abstract

PURPOSE:To obtain a miniaturized multi component force sensor having a structure which is not subjected to interference as a mechanical structure by providing two pieces of cross-shaped elastic beams interposing an intermediate connecting member and providing two pieces of distortion detecting parts in the longitudinal directions of the elastic beams, respectively. CONSTITUTION:Between the upper connecting member 1 and the lower connecting member 4a connected to two rigid bodies being measuring objects, two pieces of cross-shaped elastic beams 3, 4 are provided through an intermediate connecting member 2. In the longitudinal directions of both side faces of the cross of each elastic beam 3, 4, two pieces of respective distortion detectors 20-35 are attached. Subsequently, one end part of the cross of a first elastic beam 3 is coupled with the upper connecting member 1, and also, the other end part of the cross is coupled with the intermediate connecting member 2. Also, each end part of the cross of a second elastic beam 4 and the intermediate connecting member 2 are coupled so as to align the phase with the first elastic beam 3.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a multi-force sensor, and particularly to a force measuring device suitable for simultaneously detecting force and moment acting on a fingertip of a robot, for example.

<Prior Art> For example, in an industrial robot, in order to control the motion of the robot's fingers, a force detection device is required to detect the force or moment acting on the fingertips of the robot.

As an example of an industrial robot, as shown in FIG. 8, a robot arm 51 having a plurality of joints has a robot arm 51 at its tip, and a robot arm 56 that is opened and closed by a gripping mechanism 57. This robot repeatedly grasps a part 54 with a robot hand 56 and inserts this part 54 into the inner hole of an object 53 supplied onto a base 52. A force detection device 55 is attached between the robot hand portion 56 and the robot arm 51, and detects the force or moment that acts between the part 54 and the object 53 during work, and uses the detected information to transmit the detected information to a computer. It is input to the control circuit to correct and control the robot's working status.

As a conventional force detection device, for example, Japanese Patent Application Laid-Open No. 61-500
A sensor using a plurality of T plastic elastic beams as disclosed in Japanese Patent No. 30, a multi-axial force sensor as disclosed in Japanese Patent Application Laid-Open No. 60-62497, and the like have been proposed.

<Problems to be Solved by the Invention> However, in the detection method described in the former Japanese Patent Application Laid-open No. 61-50030, the constituent elastic beams do not react only in one direction but in response to forces in multiple directions. Because of the reaction, the force cannot be immediately detected from the amount of strain in a strain gauge bonded to the elastic beam, but has the disadvantage that it can only be determined by solving a linear equation with six elements.

On the other hand, in the latter Japanese Patent Application Laid-open No. 60-62497, it is assumed that the detection and output performance is high because it prevents interference due to forces other than those determined by the mechanical structure, but the structure is complex and the machining process is difficult. Moreover, since the cost is high and a finite length is required to generate uniform strain in the elastic beam, providing three elastic parts in the radial direction makes it impossible to achieve miniaturization and increases the weight. It has the disadvantage of being large.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a small and lightweight multi-force sensor that is mechanically free from interference and that is inexpensive to manufacture. With the goal.

<Means for Solving the Problems> As a result of intensive research to solve the above problems, the present inventor found that if the elastic beam for detecting force is divided into two layers, the length of the elastic beam can be reduced. It was discovered that it is possible to shorten the length and reduce the outer diameter of the detection device, and based on this knowledge, the present invention was completed.

That is, the present invention is a multi-force sensor that is connected between two rigid bodies that are objects to be measured and that detects the force or moment acting on these rigid bodies, and which includes two upper and lower connections that are connected to the two rigid bodies. Two cross-shaped first and second elastic beams are integrally constructed with an intermediate connecting member interposed between the members, and two cross-shaped elastic beams are formed in the longitudinal direction of both sides of the cross forming the first elastic beam. At the same time, both ends of one straight section of the cross are connected to the upper connecting member, and both ends of the other straight section that is perpendicular to this straight section are connected to the intermediate connecting member. one surface of the member is coupled to the other, and two strain detectors are attached to each longitudinal direction of both surfaces of the cross forming the second elastic beam, and the second elastic beam is formed. The multi-force sensor is characterized in that each end of the cross and the other surface of the intermediate connecting member are coupled to be in phase with the first elastic beam.

Note that the cross-shaped elastic beam may be a parallel beam formed by drilling a hole from the surface or side surface of the beam, or may be an anisotropic beam having a direction in which it is easily deformed and a direction in which it is difficult to deform when subjected to force or moment. It may also be a single beam with a uniform rectangular cross section.

<Operation> According to the present invention, the two cross-shaped elastic beams with the intermediate connecting member interposed therebetween and the upper connecting member are integrally configured, so that the strain detecting portion can be installed at two locations in the radial direction. Since the parallel beam portion of the elastic beam is provided only in the parallel beam portion, the length of the parallel beam portion of the elastic beam can be shortened, and it is possible to accurately detect distortion from any direction.

<Example> Below, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is (a) a front view of a multi-force sensor according to the present invention;
(b) A side view, (C) a plan view, and (d) a sectional view taken along the line A-A.

In the figure, reference numeral 1 denotes a disk-shaped upper connecting portion, such as a flange, which can be connected to one rigid body (not shown), such as a robot's hand. Reference numeral 2 denotes a disk-shaped intermediate connecting member, in which a first elastic beam 3 is interposed between the intermediate connecting member 2 and the upper connecting part 1, and the other surface of the intermediate connecting member 2 A second elastic beam 4 is attached to. Here, 4a is a lower connecting portion provided protruding from the center of the lower part of the second elastic beam 4, and is connectable to another rigid body (not shown), such as an arm of a robot.

Note that a flange may be interposed between the lower connecting portion 4a and the robot arm in relation to the connection means with the robot arm.

FIG. 2 is a plan view showing the first elastic beam 3, and FIG. 3 is a plan view showing the second elastic beam 4.

As shown in FIG. 2, the first elastic beam 3 is configured in a cross shape with four parallel beams 5.5' and 6°6' that are vertically and horizontally symmetrical, and each of the parallel beams 5.5' The fittings provided at the ends are fixedly connected to the upper connecting part 1 by holes 7.7' and the fittings provided in the upper connecting part 1 by holes 9, 9', and each of the parallel beams 6.6' The attachment provided at the end is fixedly connected to the intermediate coupling member 2 by means of a hole 68.8' and the attachment provided in the intermediate coupling member 2 by a hole 10.10''.

Further, in the center of the surfaces of these parallel beams 5.5' and 6.6', there are holed portions 11.11', respectively.

12 and 12' are provided to penetrate in the direction perpendicular thereto, and are configured to be easily deformed in response to force or moment in the direction to be detected. And these hole parts 11.1
Parallel beam 5.5' corresponding to 1', 12.12'
, 6.6', two strain detectors 20 to 3, such as strain gauges, are installed in the longitudinal direction on both the left and right sides of the 6.6'.
5 is glued.

On the other hand, as shown in FIG. 3, the second elastic beam 4 is configured in a cross shape by four parallel beams 13, 13' and 14, 14' which are vertically and horizontally symmetrical, similar to the first elastic beam 3. and the mounting holes 15.15', 16 provided at each end of the parallel beams 13.13', 14.14'.
16' and the attachment provided on the intermediate connecting member 2 are fixedly connected to the intermediate connecting member 2 by means of holes 17° 17', 10, 10'.

Also, these parallel beams 13.13', 14.1
Hole portion 18.1B is provided in the center of the side surface of 4'.
'.

Parallel beams 13.13' and 14.14' corresponding to the bored portions 1B, 18' and 19.19' are provided with parallel beams 19 and 19' extending through them in the right angle direction. Similarly to the first elastic beam, two strain detectors 36 to 51, such as strain gauges, are bonded in each longitudinal direction.

By configuring the multi-force sensor as described above, the force and moment acting on the upper connecting member 1 are as follows: upper connecting member 1 → first elastic beam 3 → intermediate connecting member 2 → second elastic beam 4 → lower This is transmitted to the connecting member 4a.

Next, a circuit configuration for measurement using a strain detector that detects acting force and moment will be explained using FIG. 4.

Force in the X-axis direction (F, ); as shown in Figure 4 (a),
The distortion detectors 25, 27, 32, and 34 constitute a Wheatstone bridge circuit.

As shown in the force in the y-axis direction (Fa); Fig. 4 Φ), the strain detectors 21, 23, 28, and 30 constitute a Wheatstone bridge circuit.

Force in the Z-axis direction (F, ): As shown in FIG. 4(C), strain detectors 37.39.41.43.44.46.48.
50 constitutes a Wheatstone bridge circuit.

Moment (M, )i in the X-axis direction As shown in FIG. 4(d), a Wheatstone bridge circuit is constructed by strain detectors 40, 42, 49, and 51.

Moment in the y-axis direction (My): As shown in FIG. 4(e), a Wheatstone bridge circuit is formed by the distortion detectors 36, 38, 45, and 47.

Moment in the Z-axis direction (M, ); as shown in Figure 4(f), strain detector 20.22.24.26.29.31
33 and 35 constitute a Wheatstone bridge circuit.

Here, the reason why the force or moment in the direction to be detected is not interfered with by the force or moment in other directions will be explained using the case of force F acting in two axial directions in Fig. 4(C) as an example. .

When force F8 is applied in the X-axis direction; strain detectors 37, 39 and 44
, 46 generate compressive and tensile strains of equal absolute value, and the other strain detectors 41, 43, 48, 50 do not generate any strain since they are on the neutral axis of the parallel beam 16, 16'. No output is generated from the Wheatstone bridge circuit in Figure 4 (C).

When the force F in the y-axis direction is applied, it is a force in the direction perpendicular to the force F in the X-axis direction, so it is not generated as an output of the Wheatstone bridge circuit in FIG. 4(C), similarly to when F is applied.

Moment M in the X-axis direction, when acting; strain detectors 41, 5
1 and 43.49 generate compressive bending strain and tensile bending strain with equal absolute values, and the other strain detectors 37, 39.
Although a minute torsional distortion is generated at 44.46, no output is generated from the Wheatstone bridge circuit of FIG. 4(C).

When the moment My in the y-axis direction is applied; since it is a moment perpendicular to the moment M8 in the X-axis direction, it is not generated as an output from the Wheatstone bridge circuit, similarly to when M is applied.

When the moment M in the y-axis direction is 1; the strain detectors are all on the neutral axes of the parallel beams 13.13' and 14.14', so no bending strain occurs.

As is clear from the above explanation, when detecting the force F acting in the Z-axis direction, only the force in the Z-axis direction to be detected is detected, and it is not affected by forces or moments in other directions. It can be detected.

In this way, by using the multi-force sensor of the present invention, it is possible to measure only the force or moment in the desired direction with high precision without interference from forces or moments in other directions.

It goes without saying that the present invention is not limited to application to industrial robots, but can also be used to measure forces and moments acting on tools such as machine tools.

FIG. 5 is (a) a front view and (b) a side view showing another embodiment of the multi-force sensor according to the present invention.

The first elastic beam 3A is composed of single beams 5a, 5a', 6a, 6a' as shown in detail in FIG. Single beam 13a, 13a'.

It is composed of 14a and 14a'. By configuring the elastic beam in this way, the first elastic beam 3A deforms sharply in response to forces and moments acting from the X-axis and y-axis directions, but The second elastic beam 4A deforms sharply in the Z-axis direction, but is difficult to deform in the X-axis and y-axis directions. Furthermore, such a shape is easy to machine. Note that the method of bonding and assembling the strain detector is the same as the method described above.

<Effects of the Invention> As explained above, according to the present invention, since the 2N cross-shaped elastic beam with the intermediate plate-like member interposed therebetween and the upper connecting member are integrally constructed, It can accurately detect force and moment from any direction, and can be made smaller and lighter.
Furthermore, it is possible to reduce machining costs. Therefore, it is highly expected that this will contribute to promoting the intelligence of robots in the future.

[Brief explanation of the drawing]

FIG. 1 is (a) a front view of a multi-force sensor according to the present invention;
(B) Side view, (C) Plan view, (d) A-A cross-sectional view, (a) Plan view showing the first elastic beam in FIG.
(b) Side view, Figure 3 shows the second elastic beam (a
) Plan view, (b) Side view, FIG. 4 is a circuit diagram showing the configuration of the strain detector, FIG. 5 is (a) Front view showing another embodiment of the multi-force sensor according to the present invention, 6 is a plan view showing another embodiment of the first elastic beam;
(C) Side view, FIG. 7 is a plan view showing another embodiment of the second elastic beam, Q)) Side view, and FIG. 8 is a front view showing an example of an industrial robot. be. 1... Upper connecting member, 2... Intermediate connecting member. 3... First elastic beam, 4... First elastic beam. 4a...Lower connecting member. 5, 6.13.14...Parallel beam. ? , 8. 9.10.15.16.17... Mounting is through holes. 11, 12, 18, 19...Drilling part. 20-51...Distortion detector. Patent applicant Kawasaki Steel Corporation Figure 1 Cσ (b) (
c) (d
),. Figure 2 Figure 3 Figure 4 (a) (b)
(c) ('d) (e)
(f) Figure 5 Figure 6 Figure 7 r0 no 16a a

Claims (3)

[Claims] (1) A multi-force sensor that is connected between two rigid bodies that are objects to be measured and that detects the force or moment acting on these rigid bodies, and that is between two upper and lower connecting members that connect the two rigid bodies. The cross-shaped first and second
Two elastic beams are integrally constructed, and two strain detectors are attached to each longitudinal direction of both sides of the cross forming the first elastic beam, and two strain detectors are attached to the longitudinal direction of each side of the cross forming the first elastic beam. Both ends of the upper connecting member are connected, and both ends of another straight line section that is perpendicular to this straight line are connected to one surface of the intermediate connecting member, while the second elastic beam Two strain detectors are installed in the longitudinal direction of both surfaces of the cross forming the second elastic beam, and each end of the cross forming the second elastic beam and the other surface of the intermediate connecting member 1st
A multi-force sensor, characterized in that it is coupled in phase with an elastic beam of. (2) The multi-force sensor according to claim 1, wherein the cross-shaped elastic beam is a parallel beam formed by drilling a hole from the surface or side surface of the beam. (3) A patent claim characterized in that the cross-shaped elastic beam is a single beam having an anisotropic rectangular cross section with a direction in which it is easily deformed and a direction in which it is difficult to deform when subjected to force or moment. The multi-force sensor according to item 1.