Apparatus and method for servo control system

Claim 1

In combination: a machine having a mechanical resonance frequency, and a control apparatus for controlling the machine; the machine comprising, an actuator for generating mechanical power in response to output command data; an effector for performing a commanded work; and a transmitter for transmitting mechanical power from said actuator to said effector; wherein at least one of said actuator, said effector and said transmitter has a finite mechanical rigidity; and the control apparatus comprising, detecting means for detecting a change of mechanical condition which affects the inertia moment of the machine; servo compensating calculator means operative in response to input command data and output data of said detecting means for calculating and outputting a compensating result data effective to make the machine move in accordance with said input command data; and adaptive filter means for filtering said compensating result data to suppress frequency components close to the mechanical resonance frequency of the machine, the mechanical resonance frequency changing in dependence on the change of said inertia moment of the machine, in response to said output data of said detecting means, and outputting output command data to the machine.

Claim 7

A method of servo control for a machine having a mechanical resonance frequency, comprising the steps of : detecting a change of mechanical condition which affects the inertia moment of the machine at given sampling times; calculating a servo compensating result data effective to make the machine move in accordance with position data and command data in response to said detected mechanical condition and said position data and command data; filtering said servo compensating result data to suppress frequency components close to said mechanical resonance frequency of the machine in response to said detected mechanical condition, the filtering step comprising calculating an inertia moment of the machine in response to said detected mechanical condition, calculating the mechanical resonance frequency using the inertia moment and an elasticity constant of a transmission mechanism, calculating filter coefficients using the mechanical resonance frequency, and calculating torque command data using a plurality of servo compensating result data and a plurality of torque command data taken at previous sampling times and the filter coefficients; and outputting the filtered result data to the machine as torque command data before the next sampling time.

Claim 8

A method of servo control for a machine having a mechanical resonance frequency, comprising the steps of : detecting a change of mechanical condition which affects the inertia moment of the machine at given sampling times; calculating a servo compensating result data effective to make the machine move in accordance with position data and command data in response to said detected mechanical condition and said position data and command data; filtering said servo compensating result data to suppress frequency components close to said mechanical resonance frequency of the machine in response to said detected mechanical condition, the filtering step comprising calculating an inertia moment of the machine in response to said detected mechanical condition, calculating the mechanical resonance frequency using the inertia moment and an elasticity constant of a transmission mechanism, calculating filter coefficients using the mechanical resonance frequency, and calculating torque command data using a plurality of servo compensating result data and a plurality of torque command data taken at previous sampling times and the filter coefficients; and outputting the filtered result data to the machine as torque command data before the next sampling time.