Servo control circuit

Claim 1

A servo control circuit for a servomotor, comprising: a servoamplifier comprising: a voltage supply circuit for supplying said servomotor with a drive voltage; a sensing circuit for sensing a drive current of said servomotor; a rotation sensor, coupled to said servomotor, for producing output pulses corresponding to the rpm of said servomotor; a single counter, connected to said rotation sensor, for counting the output pulses of said rotation sensor; and a servoamplifier processor, connected to said voltage supply circuit, said sensing circuit and said counter, for controlling an output voltage of said voltage supply circuit by executing current loop control during period T 1 in response to an applied torque command input and producing position information from the count; and a main processor, connected to said servoamplifier, for producing as an output said torque command by executing position and velocity loop control during a period T 2 (T 2 >T 1 ) in dependence upon the position information from said servomotor, said servoamplifier processor reading and accumulating a value from said counter during the period T 1 and delivering the accumulated value to said main processor as said position information at the end of period T 2 .