JPS5894989A - 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 structure in the joint part of an articulated robot arm, and by attaching a rotational angle position detector to the movable arm to detect the position of the rotary movable arm. This is an attempt to simplify the structure of the joint.

A rotation angle position detector is essential for controlling the rotation of an actuator, which is the drive source of a movable arm, and generally speaking, it has a shaft that is directly connected to the axis whose rotation angle is to be detected. The number of pulses proportional to the rotation angle of the shaft is generated by an optical or magnetic method, and a rotary encoder is one example.

A conventional example will be described below with reference to FIG. FIG. 1 shows an example of a joint structure of an articulated robot arm, in which an actuator 2 consisting of a servo motor is incorporated into a fixed arm 1. 6 is a speed reducer, and 6 is an output shaft of the speed reducer 6. The input shaft and output shaft of the reducer 6 are arranged concentrically and are composed of, for example, planetary gears, . A rotatable arm 7 is fixed to the output shaft 6 of the speed reducer 5, and is configured to rotate together with the output shaft 60 rotations. 4 is a detector (hereinafter referred to as an angle detector) that detects the rotation angle of the output shaft 3 of the actuator 2.

The fixed side of the angle detector 4 is attached to the fixed arm 1. Further, the shaft of the angle detector 4 is directly connected to the output shaft 3 of the actuator 2. Then, a number of pulses proportional to the rotation angle of the output shaft 3 are generated. 8゛ is a bearing.

In the example shown in FIG. 1, the number of pulses generated by the angle detector 4 is P pulse 711, and the reduction ratio of the reducer 6 is 1/N.
Then, the output angle of the actuator 2 is rotated, and the angle detector 4 generates a pulse of Pl.

As shown in Fig. 1, when the angle detector 4 is attached to the end 1' of the fixed arm 1, the end 1' should be attached in a way that avoids the movable arm's movable range and the external protrusions of the joint. In particular, when the rotation angle of the movable arm becomes 180° or more, it becomes difficult to attach the end portion 1' to the arm 1 due to dimensional constraints.

Therefore, in the present invention, the angle detector 4 is attached to the movable arm 7, thereby simplifying the structure of the angle detector 4. An example of this structure is shown in FIG.

JP-A-58-94989 (2) In FIG. 2, 1 to 8 are the same as in FIG. 1, and therefore their explanations will be omitted. In FIG. 2, when the output shaft 3 of the actuator 2 rotates, the shaft of the angle detector 4 directly connected to it rotates, and the input shaft of the reducer 5 also rotates, and is therefore fixed to the output shaft β of the reducer 6. and the output shaft 6
The movable arm 7, which rotates concentrically, will rotate. Here, the angle detector 4 is connected to a movable arm 7 as shown in FIG.
Since it is mounted concentrically with the shaft 3 on the end 7' of the angular position detector 4, the fixed part of the angular position detector 4 moves relative to the shirt, and the number of generated pulses is as shown in Fig. 1. It will be different.

Here, the number of pulses generated per one rotation of the shaft of the angle detector 4 is set to one rotation of the shaft, and the reduction ratio of the reduction gear 6 is set to 17N.
Then, when the actuator shaft 3 rotates once, the arm rotates by an angle of 3600X- as in the case of Fig. 1, but the number of pulses generated by the angle detector is determined by the rotation of the input and output shaft of the reducer The first one depends on whether the directions are the same or not.
Increase or decrease compared to the case shown in the figure. That is, if the rotational directions of the input shafts 3 and 5 output shafts 6 of the reducer 5 are the same, then N-1 p0=p--,,=p()... (
1) N N , and if the rotation direction is different, P N
+1 pop-p + -= p (-) ・・・・・・・・・
...(2) N N . P if N>>1. zP, and the influence on the rotation detection resolution due to the attachment of the angle detector 4 to the movable arm 7 is almost eliminated. Furthermore, as can be seen from equation (2), when the rotation directions of the input shaft and output shaft of the reducer 5 are different, the apparent resolution of the angle detector 4 can be increased as a result.

As described above, the present invention attaches an angular position detector to a movable arm that is moved by an actuator for driving the joint of an articulated robot arm, and the relative rotation angle between the rotation angle of the movable arm and the rotation angle of the shaft of the actuator. Since the actuator is controlled by the difference, it has the advantage of simplifying the structure of the robot's joints and increasing the apparent resolution of the angular position detector, which is extremely effective. There is something.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a robot joint according to a conventional example, and FIG. 2 is a cross-sectional view showing the joint structure of a robot according to an embodiment of the present invention.
2...actuator, 3...output shaft, 4...position detector, 7...movable arm.

Claims (1)

[Claims] It includes a fixed arm and a movable arm, an actuator that drives the movable arm, a reducer that decelerates the movement of the actuator and transmits it to the movable arm, and a position detector that controls the rotation of the output shaft of the actuator. Ta,
A robot in which the fixed side of the position detector is attached to a movable arm, and the movable shaft of the position detector is directly connected to the output shaft of an actuator.