Electricity: motive power systems – Positional servo systems – 'reset' systems
Reexamination Certificate
1999-09-13
2001-03-20
Masih, Karen (Department: 2837)
Electricity: motive power systems
Positional servo systems
'reset' systems
C318S560000, C318S632000, C318S561000, C318S618000, C318S610000, C318S116000
Reexamination Certificate
active
06204622
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a position controller for motors, robots, machine tools, etc., and in particular to a position controller for which a high speed response is required.
BACKGROUND ART
As a position controller aiming at a high speed response, for example, a position controller is available, which is provided with a command generator for generating position instructions, a position control unit for controlling a position by inputting a position instruction and the position of a motor being an object to be controlled, and outputting a speed instruction so that they become coincident with each other, a speed control unit to control a speed by inputting a speed instruction and a speed of the motor, and outputting a torque instruction so that they become coincident with each other, and a current control unit for controlling a current on the basis of the inputted torque instruction, and further provided with a subtracter which obtains a speed deviation by subtracting the speed from the speed instruction, an integrator which obtains an integral figure of the speed deviation by time-integrating the speed deviation with a time constant Ti, a multiplier for multiplying the speed instruction by &agr;(0.0≦&agr;1.0), an adder and subtracter which adds a signal of the multiplier to an integral figure of the speed deviation and at the same time subtracts the speed therefrom, a multiplier for multiplying an output of the adder and subtracter by a speed loop gain, and a torque filter for filtering a signal of the multiplier through a low-pass filter and making it into a new torque instruction.
However, there is such a problem by which in cases where the speed loop gain is increased or where the time constant is shortened, the control system itself may be likely to vibrate by delay of the torque filter consisting of a low-pass filter secured to suppress vibrations induced by the mechanical system.
DISCLOSURE OF INVENTION
It is therefore an object of the invention to provide a position controller to solve the problem. A position controller according to the first claim of the invention has a command generator for generating position instructions, a position control unit for controlling a position by inputting a position instruction and the position of a motor being an object to be controlled, and outputting a speed instruction so that they become coincident with each other, a speed control unit for controlling a speed by inputting a speed instruction and a speed of the motor and outputting a torque instruction so that the speed instruction and speed become coincident with each other, and a current control unit for controlling a current on the basis of the torque instruction, wherein the speed control unit is provided with a speed feedback filter which obtains a new speed of a motor by filtering the speed through a low-pass filter, a subtracter which obtains a speed deviation by subtracting the new speed from the speed instruction, an integrator which obtains an integral figure of the speed deviation by time-integrating the speed deviation by a time constant Ti, a multiplier which multiplies the speed instruction by &agr;(0.0≦&agr;1.0), an adder and subtracter which adds a signal of the multiplier to the integrated figure of the speed deviation and subtracts the speed therefrom, a multiplier which calculates a torque instruction by multiplying the output of the adder and subtracter by a speed loop gain kv, and a torque filter which makes a torque instruction into a new torque instruction by filtering it through a low-pass filter.
A position controller according to the second claim of the invention is featured in that the position control unit is provided with a speed feed forward device which multiplies the position instruction by a speed feed forward constant FF (0.0≦FF≦1.0) after differentiating the position instruction by time, and an adder which obtains a new speed instruction by adding a signal of the speed feed forward device to the speed instruction.
A position controller according to the third claim of the invention is featured in that the speed control unit is provided with a torque feed forward device which differentiates the speed instruction by time and makes it (motor inertia+load inertia)−fold, and multiplies it by the torque feed forward constant FFa (0≦FF≦1), and an adder which obtains a new torque instruction by adding a signal of the torque feed forward device to the signal of the multiplier.
REFERENCES:
patent: 5952804 (1999-09-01), Hamamura et al.
Armstrong Westerman Hattori McLeland & Naughton LLP
Kabushiki Kaisha Yaskawa Denki
Masih Karen
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