SERVO CONTROL METHOD BY THE DISTURBANCE ESTIMATION OBSERVER

摘要

A servo control method which, even in the case of a machine having a large variation in inertia, makes it possible to properly estimate and remove disturbance by the disturbance estimation observer so that the machine exhibits improved immunity against disturbance. An estimated disturbance (x) is found based on the actual instruction (I-y') and the actual motor speed (v) by a disturbance estimation observer(5) equipped with four transfer elements (51 to 54) that have transfer functions (Kt/Jm,K1,K2/S,1/S)determined by values corresponding to torque constant(Kt), inertia(Jm) and parameters(K1, K2). The gain is adjusted by the transfer element(3) and high-frequency components are removed by the filter (4), whereby a corrected estimation disturbance (y') is found. A servo motor is driven by the actual instruction current obtained by subtracting a corrected estimation disturbance from the instruction current (I), so that the effect of disturbance is removed. The parameter (jm) of transfer functions (3,51) is variably set depending upon a change in the inertia of the machine that stems from a change in the operation condition of the machine, and disturbance is properly estimated and is removed even when the inertia varies to a greater extent.