JPH11353028A - Command control method in motion controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart a speed command for suppressing sudden fluctuation at the time of switching speed control and position control by obtaining a command value from a virtual command position, a feedback position and a position loop gain at the time of switching to the position control. SOLUTION: A position loop is not used as the speed command prepared by a speed command generation part 8 and input to a speed control part 2 during a fixed speed from acceleration. A speed command switching device 10 is switched to the side of the terminal (a). In the meantime, the speed command generated in the speed command generation part 8 and a feedback signal from a position detector 6 are inputted to a virtual position control part 9 and a virtual position is obtained and fetched to a position control part 1. A position signal switching device 11 is switched to the side of the terminal (b). The position signal switching device 11 and the speed command switching device 10 are respectively switched to the side of the terminal (a) and shifting to a position control mode is performed. The obtained virtual position is used for the speed command and an actual feedback position prepared in the position control part 1 is used thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a command control method in a motion controller such as a positioning controller using a servomotor, and more particularly, to a switching control method between speed control and position control.

[0002]

2. Description of the Related Art A conventional position control method of a motion controller will be described with reference to FIGS. In FIG.
1 is a position control unit, 2 is a speed control unit, 3 is a current control unit and a power control unit, 4 is a current detector, 5 is a servo motor, 6
Is a position detector, and 7 is an F / V converter. The position of the servo motor 5 is controlled by using the position control loop as a main loop, the speed control loop, and the current control loop as a minor loop. The command is given as an absolute position or increment value,
It is converted by the position control unit 1 to generate a speed command. If the characteristics of the combination of the speed control unit (speed control unit 2, current control unit and power amplification unit 3) and servo motor 5 are simply viewed as a temporary delay system, the control block diagram of FIG. 3 is as shown in FIG. expressed. In FIG. 4, Pi (s) is a position command, Po (s) is a position output, Kp is a position loop gain, Kv is a speed loop gain, and s is a Laplace operator.

[0003]

When the position loop gain Kp for driving a machine with low rigidity by the servomotor 5 is low, if a position loop is provided at the time of constant speed traveling, an oscillation system is easily formed in the position loop. And the high-speed movement cannot be performed because the position loop gain Kp cannot be set high. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of providing a speed command that realizes quick positioning and suppresses abrupt fluctuation when switching between speed control and position control.

[0004]

According to the present invention, in a command control method for a motion controller, a command at a constant speed is given at the time of speed control, a virtual command position is derived from the command value and a position loop gain, and the control is switched to position control. Sometimes, the virtual command position is assumed to be a current position, and a command value is obtained from the value, a feedback position, and a position loop gain, thereby providing a command control method in a motion controller.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the servo system control block diagram of FIG. 3, a virtual position controller 9, a speed command generator 8, a speed command switch 10,
The position signal switch 11 is added. The description of the same reference numerals as in FIG. 3 is omitted. In FIG. 1, when a command is given, a speed command created by the speed command creating unit 8 is used as an input to the speed control unit 2 without using a position loop during a period from acceleration to a constant speed. As shown, the speed command switch 10 is switched to its terminal b. On the other hand, the speed command created by the speed command creating unit 8 and the feedback signal from the position detector 6 are input to the virtual position control unit 9, where the virtual position is obtained by the following formula (1). . Pv = Qr + Vs / Kp (1) where Pv: virtual position, Qr: actual feedback position, Vs
: Speed command, Kp: Position loop gain. The calculation by the above formula (1) is always performed, and the virtual position is taken into the position control unit 1. As shown, the position signal switch 11 is switched to its terminal b. FIG. 2 is a diagram showing a time change of the speed command. When the command enters the deceleration point indicated by A in FIG. 2, the position signal switch 11 and the speed command switch 10 in FIG.
Side, and shifts to the position control mode. The speed command at the time of the switching is obtained by the following equation (2) using the obtained virtual position. Vs = (Pr−Pv) × Kp (2) Here, Pr indicates a command position. The speed command value is obtained by the above equation (2) only when switching to the position control. Thereafter, the speed command value is obtained by the following equation (3) using the actual feedback position created by the position control unit 1. . Vs = (Pr−Qr) × Kp (3)

[0006]

As described above, according to the present invention, even a machine having low rigidity does not have a position loop during steady running, so that smooth movement can be performed, and feedback at the moment of switching to position control. By virtually calculating the position, the deviation from the actual feedback position can be reduced, whereby the fluctuation of the speed command value can be suppressed, and the occurrence of a peak in the response can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a time change of a speed command;

FIG. 3 is a block diagram for explaining a conventional position control method.

FIG. 4 is a control block diagram of FIG. 3;

[Explanation of symbols]

Reference Signs List 1 position controller 8 speed command generator 2 speed controller 9 virtual position controller 3 current control and power amplifier 10 speed command switch 4 current detector 11 position signal switch 5 servo motor 12 speed control unit + motor 6 position Detector 7 F / V converter

Claims (1)

[Claims] In a command control method for a motion controller, a command at a constant speed is given during speed control,
The virtual command position is derived by adding the real feedback position to the value obtained by dividing the speed command value by the position loop gain, and when switching from the speed control to the position control, the deviation between the position command value and the virtual command position is calculated. A command control method in a motion controller, wherein a speed command value is obtained by multiplying by a position loop gain.