JPH01316189A - Controller for manipulator - Google Patents

Abstract

PURPOSE:To perform a stabilized drive control corresponding to a position presided by a holding unit and realize a work with high safety and lighten a manipulator, by providing a drive current control means for controlling a switching of a current for torsion joint drive corresponding to a current limitation level selecting signal from a computing means. CONSTITUTION:A holding unit for to be worked is provided to a torsion joint 10 via multiple bending joints, and bending angle of these bending joints are detected by detecting means 20-22. On the basis of the angle signals detected by the detecting means 20-22, a space between the torsion joint 10 and a holding unit is detected by a computing means 23 so as to generate a current limitation level selecting signal of a current for torsion joint drive. The current for torsion joint drive is controlled by a drive current control means corresponding to the current limitation level selecting signal, and a rough constant force is given to each unit including the holding unit, corresponding to a position presided by the holding unit so as to realize a work with high safety without damage on a pay load.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for a manipulator that performs various operations in, for example, outer space.

(Prior Art) In general, a manipulator has a rotatable torsion joint, for example, a torsion shoulder joint 10, mounted on a body structure 11, as shown in FIG. , for example, bent shoulder joint 12, bent elbow joint 13,
After the bending wrist joints 14 are connected in sequence via the arms 1.5.16, a grip part 17 for work is attached to the tip thereof. Drive actuators such as motors of these torsion shoulder joint 109, bending shoulder joint 121, bending elbow joint 139, and bending wrist joint 14 are controlled by command signals from a control device (not shown).

At this time, the torsion shoulder joint 10 is required by the control device to have its maximum output torque T at the position of the longest distance L3 among the positions LL, L2 and L3 controlled by the grip portion 17. The drive current of the drive unit is set to correspond to the maximum output torque T.

However, in the above-mentioned manipulator, the drive current of the torsion shoulder joint 10 is controlled so that the maximum output torque T corresponding to the distance #tL3 can be obtained. Controlling distances Ll, L2.
According to L3, its torsion shoulder joint 10, bending shoulder joint 12
, bent elbow joint 13, bent wrist joint 14, arm 15,1
6. Since the force applied to the gripping part 17 is different as Fa - T / La > Fb - T / Lb > Fc - T / Fc, the strength of each part is adjusted to have a robust structure corresponding to the maximum force Fc. By having to form
It has the problem of being heavy. Also, according to this,
Since a very large force is applied to the grip portion 17 at the position La, there is a risk of damaging the payload to be worked, and this poses a safety problem. Ta.

This poses a major problem in terms of transportation and reliability of work, especially for manipulators used in outer space.

(Problems to be Solved by the Invention) As described above, conventional manipulators are heavy and have the disadvantage of causing damage to the payload.

This invention has been made in view of the above circumstances, and enables stable drive control according to the position controlled by the gripping part, thereby realizing highly safe work and reducing the weight of the manipulator. It is an object of the present invention to provide a control device for a manipulator that can contribute to improvement.

[Structure of the Invention (Means for Solving the Problems)] The present invention provides a control device for a manipulator in which a torsion joint is provided with a grip portion for a workpiece via a plurality of bending joints. a detection means for detecting a bending angle; and a calculation means for detecting a distance between the torsion joint and the grip portion from the angle signal detected by the detection means and generating a current limit level selection signal for a current for driving the torsion joint; The driving current limiting means switches and controls the current in response to the current limiting level selection signal of the calculating means.

(Function) According to the above configuration, the drive current of the torsion joint is controlled by the drive current limiting means in accordance with the position controlled by the grip portion, and the output torque at each position is variably set. Therefore, a substantially constant force is applied to each part including the gripping portion in accordance with the position controlled by the gripping portion, thereby realizing highly safe work without damaging the payload, and By eliminating the need for each part to have a rigid structure to the extent that it can handle the maximum force applied as in the past, weight reduction can be improved.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a manipulator control device according to an embodiment of the present invention. Here, the same parts as those of the manipulator shown in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, 20 to 22 respectively indicate the above-mentioned bending shoulder joint 1.
2. Angle sensors provided at the bent elbow joint 13 and the bent wrist joint 14, each output end of which is connected to the calculation unit 23. This calculation unit 23 detects the position of each joint 12 to 14 from each angle signal from the angle sensors 20 to 22, calculates torques Ta, Tb, and Tc corresponding to the posture, and converts the torques Ta1 to Tb and Tc. The current limit signal of the upper limit value of the corresponding current is calculated and determined, and the current limit signal is sent to the current limit circuit 2.
Output to 4.

The current limiting circuit 24 receives the detected current of the driving motor 25 of the torsion shoulder joint 10 via a current detector 26, and as shown in FIG. is selectively switched to fixed contacts S, C, and D in response to the current limit signal, and the drive motor 2
A voltage signal for gaining the upper limit of the drive current of No. 5 is output to the amplifier 26. A torque command generated by subtracting the speed command from the manipulator control unit 28 and the rotation speed signal from the rotation angle sensor 25a of the drive motor 25 using a subtracter 29 is input to the amplifier 27, and this torque The drive current corresponding to the command is gained by the voltage signal and output to the drive motor 25. As a result, the drive motor 25 has a torque Ta corresponding to the posture controlled by the grip portion 17.
.

The drive is controlled so that T b ST c, where,
The driving force is reduced by the reducer 25b, and the torsion shoulder joint 1
Activate 0. At this time, positions A and B controlled by the grip portion 17
, the force Fa'-Ta/La in C.

Fb'-Tb/Lb, Fc'-Tc
/Fc is such that each torque Ta, Tb, ,Tc is a distance La
,Lb.

By controlling the upper limit in accordance with Lc, the road distance is controlled to -.

In this manner, the control device for the manipulator detects the posture position of the gripping portion 17 from the angular positions of the bent shoulder joint 12, the bent elbow joint 13, and the bent wrist joint 14, and adjusts the driving position in accordance with the detected posture position. By controlling the drive current of the motor 25 and setting the output torques Ta, Tb STc at each position to be substantially constant, the force applied to each part including the grip portion 17 is made substantially constant. This makes it possible to perform highly safe work without the risk of damaging the payload, unlike conventional methods. Also, according to this,
This eliminates the need for the structure of the manipulator to be strong enough to withstand the maximum force as in the past, which also contributes to improved weight reduction.

In addition, in the above embodiment, the bending shoulder joint 1 is used as the bending joint.
2. Although the present invention is constructed using the bent elbow joint 13 and the bent wrist joint 14, the present invention is not limited to this number and can be applied. Therefore, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to perform stable drive control according to the position controlled by the gripping portion, thereby realizing highly safe work, and It is possible to provide a manipulator control device that can contribute to improved weight reduction of the manipulator.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control device for a manipulator according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing details of the current limiting circuit in FIG. 1, and FIG. 3 explains problems with the conventional method. FIG. 2 is a configuration diagram showing a manipulator shown for this purpose. 10... Torsional shoulder joint, 11... Groove body for installation, 12
...bending shoulder joint, 13...bending elbow joint, 14...
Bending wrist joint, 15.16...Arm, 17...Gripping part, 20-22...Angle sensor, 23...Calculating unit, 24...Current limiting circuit, 24a...Switching unit ,2
5... Drive motor, 25a... Rotation angle sensor, 25
b...Reducer, 26...Current detector, 27...Amplifier, 28...Manipulator control unit, 29...Subtractor. Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] In a control device for a manipulator, a control device for a manipulator is provided with a grip portion for a workpiece via a plurality of bending joints with respect to a torsion joint,
a detection means for detecting the bending angle of the bending joint, and a distance between the torsion joint and the grip portion detected by the angle signal detected by the detection means to generate a current limit level selection signal for a current for driving the torsion joint. A control device for a manipulator, comprising: a calculation means; and a drive current limit means for switching and controlling the current in response to the current limit level selection signal of the calculation means.