JPS5894991A - Device for fixing joint of robot - 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 The present invention relates to a joint fixation device for a robot having joints.

In recent years, there has been an active development of articulated assembly robots that can perform simple assembly tasks in place of humans.

Incidentally, some assembly operations involve a large reaction force, such as the tightening of screws, and in this case, it is necessary to prevent joints from moving due to the reaction force.

Therefore, conventionally, for example, as shown in FIG. 1, stoppers 6 and 4 as shown in the figure are provided near the shaft connection of arms 1 and 2 constituting one joint, and the mechanical hand 5 attached to the arm 2 is Even if a reaction force is applied from the direction of arrow A, the reaction force prevents arm 2 from rotating further to the right in direction of arrow B from the state shown in the figure relative to arm 1, and a servo motor (not shown) that drives arm 2 is used. The generated torque of the servo motor can be changed according to the reaction force so that the motor torque always overcomes the reaction force, or a reducer with poor reverse transmission efficiency can be used as a reducer to reduce the output of the servo motor. Arm 2 was prevented from rotating.

However, fixing the joints using stoppers has the disadvantage that the angles that can be fixed are limited, and in order to change the torque of the servo motor, not only must a motor with a wide generation torque range be prepared, but the control becomes complicated. The drawback is that even with such K, there is a limit to the amount of reaction force that can be overcome.

Furthermore, using a reducer with poor reverse transmission efficiency limits the degree of freedom in selecting the reducer, which is not very practical due to the structure of the robot.

The present invention has been made in view of the above points, and provides a joint fixing device for a robot that fixes the joints using a brake means that can arbitrarily brake the movement of the joints of the robot, thereby solving the conventional problems. It measures the

Embodiments of the present invention will be described below with reference to FIG. 2 and subsequent drawings.

FIG. 2 is a configuration diagram showing an example of an articulated robot to which the present invention is applied.

In the same figure, an upper arm 8 is connected to a shoulder part 7 rotatably attached to a base 6 so as to be rotatable in the direction of arrow C through a shaft 7a, and a middle arm 9 is connected to the distal end of the upper arm 8 through a shaft 8a. They are connected so that they can rotate in the direction of the arrow.

Further, a first lower arm 10 is attached to the tip of the middle arm 9 by a shaft 9a.
The first lower arm 10 has a shaft 10 provided in a direction perpendicular to the shaft 9a at the distal end of the first lower arm 10.
The second lower arm 11 is rotatably connected in the direction of arrow F by a.

Further, a wrist 12 to which a mechanical hand 13 is attached is connected to the distal end of the second lower arm 11 via a shaft 11a so as to be pivotable in the direction of arrow G.

Each joint of the multi-joint robot configured in this manner is provided with a brake means for braking the movement of the joint.

An example of this braking means will be explained by taking a wrist joint formed by the second lower arm 11 and the wrist 12 as an example.

FIG. 6 is a longitudinal cross-sectional view of the wrist joint, which is the connecting portion between the second lower arm 11 and the wrist 12 in FIG.

First, to explain the drive system, shaft members 14 and 15 (brackets) 11b and 11b of the second lower arm 11 are fixed respectively.
The wrist 12 is rotatably attached to the shaft 11a (corresponding to the shaft 11a in FIG.
8, 19 and a flange surface 21 at one end via the reducer 20.
The hollow shaft 21 with a is attached.

Then, a rotor 22 to which a permanent magnet is fixed is fixed to the outer periphery of the hollow shaft 21, and an electromagnet 23 is attached to the inner periphery of the hollow part 12a of the wrist 12 corresponding to the rotor 22. 22, an electromagnet 26, etc. constitute a motor.

The speed reducer 20 has a structure similar to that of the one called "No-Monique Drive" (trade name).

That is, on the outer periphery of the cam 21b, which is formed by making the outer periphery of one end of the hollow shaft 21 into an elliptical shape, a large number of balls 24 are fitted in two rows following the periphery of the cam 21b to form a wave generator.

The outer periphery of this wave generator, that is, the ball 24
．． A flex spline 25 made of a thin cylindrical elastic body having a large number of spline teeth (not shown) carved in the generatrix direction on the outer periphery is fitted onto the outer periphery of the flex spline 24 .

On the outer periphery of the flex spline 25, a shaft member 15 is fitted, which has spline-like teeth engraved on the inner periphery by one or two more than the number of teeth of the flex spline 25.

Similarly, on the outer periphery of the flex spline 25, a shaft member 15
The wrist 12, which has spline-like teeth carved on the inner periphery of the hollow part 12a, is inserted into the wrist 12, which has spline-shaped teeth engraved on the inner periphery of the hollow part 12a.

Therefore, by passing a current through the electromagnet 26 constituting the motor, the hollow shaft 21 rotates together with the rotor 22.
The rotation is reduced by the speed reducer 20 and transmitted to the wrist 12, thereby causing the wrist 12 to pivot around the shaft member 14.15.

Note that a slit disk 26 is attached to the outer periphery of the hollow shaft 21, and light emitting elements and light receiving elements (not shown) provided on the slit disk 26 and the protruding portions 27 and 28 of the inner circumference of the hollow portion 12a of the wrist 12, respectively. The elements constitute a photoelectric incremental rotary encoder.

Next, the brake means will be explained.

The braking means includes an electromagnet 29 provided on the shaft member 14, an unrotatable sliding body 61 that is always urged in the direction of arrow H by a spring 60, and a friction member fixed to the side surface of the sliding body 31 on the side of the hollow shaft 21. It consists of a plate 62.

Then, by energizing the electromagnet 29 and attracting the sliding body 61 against the spring 60 to the illustrated position,
The wrist joint is allowed to rotate, the electromagnet 29 is de-energized, and the sliding body 61 is moved in the direction indicated by the arrow H by the biasing force of the spring 60.
By moving the friction plate 62 in the direction of the hollow shaft 2
1, and thereby applies a brake to the movement of the wrist joint.

The brake control means, which is a current supply control circuit for the electromagnet 29 constituting the brake means, is constructed as shown in FIG. 4, for example.

As shown in FIG. 4, the electromagnet 29 is always energized via the normally closed contact 33a of the relay 66, and when a power cutoff command is output from the robot controller 64 via the interface 35, the amplifier 66 is turned on. Coil 33 of relay 66
A current is caused to flow through the terminal b, thereby opening the normally closed contact 33a and cutting off the energization of the electromagnet 29.

Therefore, while the control unit 64 outputs the power interruption command, the above-mentioned braking means operates to brake the movement of the wrist joint, thereby fixing the wrist joint.

Although the above description is about the wrist joint, the other joints shown in FIG. 2 have substantially the same configuration.

Therefore, by bending each joint to an arbitrary angle and then applying braking to the movement of each joint using the brake means, each joint can be fixed in that state.

For example, if the second lower arm 11 and wrist 12 are bent at 90 degrees as shown in FIG. Even if a thrust reaction force in the direction A is applied to the wrist joint, the wrist joint does not move due to the reaction force, and the screw tightening work can be performed smoothly.

Furthermore, since the braking means is a non-excitation type brake as shown in FIG. 3, there are some moving parts in which the bent state of each joint is maintained even when the power is cut off, such as a power outage.

In the above embodiment, an example in which a friction plate is used as the braking means is described, but the invention is not limited to this. (For example, if a ratchet gear is attached to the drive shaft of the joint, Braking means may be used that advances and retreats a lock pin operated by a Branjan lenoid.

As described above, the robot joint fixing device according to the present invention can brake and fix joints at any angle without using special servo motors or reducers. This is convenient because the braking force can be set freely.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a conventional robot joint fixing device, FIG. 2 is an external view showing an example of an articulated robot to which the present invention is applied, and FIG. 6 is an implementation of the method shown in FIG. FIG. 4 is a block diagram showing an example of the brake control means, and FIG. 5 is a state in which the wrist joint is fixed according to the embodiment shown in FIGS. 2 to 4. FIG. 6...Base 7...Shoulder 7
a, 8a, 9a, 11a...Axis 8...
Upper arm 9...Middle arm 10...
1st lower arm 11... 2nd lower arm 12...
・・Wrist 16・・・・Mechanical No. 2
9...Electromagnet 62...Friction plate 66...Relay Figure 1 Figure 3

Claims (1)

[Claims] 1. A robot joint fixing device for a robot having joints, comprising: a brake means for braking the movement of the joints of the robot; and a brake control means for controlling the brake means.