Patent ID: 6184644
Filing Date: 2001-02-06
Classification: G05B

Abstract:
A position control apparatus for controlling the position of an object, which is driven via a ball screw drive system by a servomotor, based on a predetermined command, said apparatus having a deflection compensation command section for outputting at least one of the following values:a deflection compensation value,a deflection speed compensation value, anda torque compensation value;for compensating a control error due to a possible deflection of a ball screw drive system, said at least one compensation value being calculated based on:a position command value,an acceleration command value, anda torque command value,wherein said deflection compensation command section is equipped with a compensation extent determination section including(a) parameter determination section having:1) an integrated thrust rigidity determination section for calculating an integrated thrust rigidity of the ball screw drive system based on said position command value,2) an integrated torsional rigidity determination section for calculating an integrated torsional rigidity of the ball screw drive system based on said position command value,3) a load-side inertial moment determination section for calculating a current load-side inertial moment based on said acceleration command value, said torque command value the current motor speed, said integrated thrust rigidity, said integrated torsional rigidity and a load-side inertial moment in previous cycle;(b) a first amplifier for multiplying said acceleration command value by a reciprocal number of said integrated thrust rigidity calculated by said parameter determination section;(c) a second amplifier for multiplying said acceleration command value by a reciprocal number of said integrated torsional rigidity calculated by said parameter determination section;(d) an adder for obtaining a combined output of said first and second amplifiers; and(e) a third amplifier for calculating a deflection extent by multiplying the output of said adder by said load-side inertial moment calculated by said parameter determination section.