JPH0899278A - Robot controller - Google Patents

Abstract

PURPOSE: To improve precision and a response speed by employing a feed- forward controlling method in a robot controller controlling an interpolating action by which a robot is moved while drawing a linear or curved or bit between a moving point and another moving point. CONSTITUTION: A feed-forward controlling method is used for an interpolating action requiring precision and response speed, while an ordinary feedback controlling method is employed for a PTP action (an action in which movement between two positions is carried out at the shortest speed) requiring no precision and no response speed, so that stability of the action is improved. In the feed- forward controlling method, a command signal is processed in a such way as is shown in a position control block, and then, a position signal is outputted. Kpf represents a position feedback constant, Kv represents a servo-amplifire speed constant, Tv represents a servo-amplifier response delay time, Kp represent a speed/position conversion constant, Td represents a feedback loop waste time factor, and Kff represents a feed-forward compensation constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller. More specifically, the control performance of the robot is improved.

[0002]

2. Description of the Related Art An example of a conventional robot controller is shown in FIG. In the figure, 1 is a CRT interface unit, 2 is a control CPU, 3 is an interpolation calculation CPU, and 4 is a servo calculation CP.
U, 5 are dedicated key interface units, 6 is a teaching box interface unit, 7 is an encoder interface unit, 8 is a servo interface unit, and 9 is C.
RT (display), 10 is a panel operation key, 11 is a teaching box, and 12 is a servo amplifier.

The operation of the robot is roughly classified into two types, that is, a PTP operation for moving the moving point and the moving point at the shortest speed, and an interpolating operation for moving the moving point and the moving point by drawing a trajectory of a straight line or a circular arc. . In the PTP operation, since the start point and the end point are controlled simultaneously for each axis by the trapezoidal speed pattern in the shortest time, the operation speed is considerably high, while the interpolation operation is
Since the start point and the end point of the moving point are moved by a straight line or a circular arc, the operation speed is not as fast as the PTP operation, but the trace accuracy of the trajectory and the response speed during adaptive control are required.

[0004]

As a position control system of the above-mentioned robot controller, a feedback control system is adopted as shown in FIG. Here, each constant is as follows. K _pp : Position feedback loop, proportional gain K _v : Servo amplifier speed constant T _v : Servo amplifier response delay time K _p : Speed / position conversion constant K _pf : Position feedback constant

However, there is a problem that a trajectory shift occurs when the interpolation operation is performed by the feedback control method, and there is a problem that the response to the applied control is slow. The present invention has been made in view of the above-described conventional art, and an object of the present invention is to provide a robot control device having improved robot control performance in interpolation operation.

[0006]

The structure of the present invention which achieves such an object is a robot control device for performing an interpolating operation for moving a robot by drawing a straight or circular trajectory between moving points. In the above, a feedforward control method is adopted. Further, the configuration of the present invention that achieves the above-mentioned object is an interpolation operation for moving a robot by drawing a straight or circular trajectory between moving points or a PTP for moving the moving points and the moving points in the shortest time. A feature of the robot controller for performing the operation is to switch to the feedforward control method when performing the interpolation operation.

[0007]

The feedforward control, which is useful for improving accuracy and response speed, may become unstable when the operating speed is high. Therefore, in the interpolation operation that requires accuracy and response speed, the feedforward control method is adopted,
Alternatively, the accuracy and response speed are improved by switching to the feedforward control method. On the other hand, in the PTP operation in which accuracy and response speed are not required, the stability is enhanced by adopting the normal feedback control method.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. One embodiment of the present invention is shown in FIG. As shown in the figure, in this embodiment, a feedforward control system is adopted in the interpolation operation which requires accuracy and response speed. Here, each constant is as follows.

K _pp : Position feedback loop, proportional gain K _v : Servo amplifier speed constant T _v : Servo amplifier response delay time K _p : Speed / position conversion constant K _pf : Position feedback constant T _d : Feedback loop dead time element K _ff : Feedforward compensation constant

As described above, in this embodiment, since the feedforward control system is adopted for the interpolation operation, the accuracy and the response speed can be improved and the following effects can be obtained. (1) It is possible to improve the accuracy and the response speed during the interpolation operation without increasing the gain of the position control block, and thus the stability of the position control block is increased. (2) The position deviation pulse is compressed to about 1/10, and the response is improved to the response delay time of the speed control unit (shortened to about 1/4).

The feed-forward control method is not applied to the PTP operation in which accuracy and response speed are not required, because it may become unstable when the operation speed is high.

Therefore, in the robot controller which performs two operations, the PTP operation and the interpolation operation, it is necessary to switch the control method according to the type of operation. For example, in FIG.
As shown in FIG. 1, it is determined whether the operation is the interpolation operation or the PTP operation. In the case of the interpolation operation, the feedforward control method is switched to that shown in FIG. 1, and in the case of the PTP operation, the normal position control processing is performed. It is better to switch to the feedback control method (see FIG. 3).

[0013]

As described above in detail with reference to the embodiments, according to the present invention, since the feed-forward control system is adopted in the robot controller for performing the interpolation operation, the accuracy and the response speed are improved. Will be improved. Further, in the robot controller that performs the interpolation operation or the PTP operation, when the interpolation operation is performed, the feedforward control method is switched, so that the accuracy and the response speed are improved.

[Brief description of drawings]

FIG. 1 is a position control block diagram of a robot controller according to an embodiment of the present invention.

FIG. 2 is a flowchart showing position control of the robot controller according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional robot controller.

FIG. 4 is a position control block diagram of a conventional robot controller.

[Explanation of symbols]

 1 CRT interface section 2 Control CPU 3 Interpolation calculation CPU 4 Servo calculation CPU 5 Dedicated key interface section 6 Teaching box interface section 7 Encoder interface section 8 Servo interface section 9 CRT (display) 10 Panel operation key 11 Teaching box 12 Servo amplifier

Claims (2)

[Claims] 1. A robot controller characterized by adopting a feedforward control system in a robot controller for performing an interpolating operation for moving a robot by drawing a trajectory of a straight line or an arc between the moving points. apparatus. 2. A robot controller for performing an interpolation operation for moving a robot by drawing a straight or circular trajectory between moving points and a PTP operation for moving the moving point and the moving point in the shortest time. A robot controller characterized by switching to a feedforward control method when performing an interpolation operation.