Reduction of motor speed fluctuation using repetitive control

Repetitive control can be used to eliminate the influence of periodical disturbance. The authors describe an attempt to reduce fluctuation in motor speed, which is usually periodical, by detecting the instantaneous speed with a spatial filter and by feeding back the sensor output through a repetitive controller. A design procedure with two independent steps for speed regulation and fluctuation reduction is proposed. A method of stabilization using sampler and phase-lead compensation is also developed, as well as time-delay synchronization by a phase-locked loop. An experimental setup indicated reduction of speed fluctuation down to a level of 1/5.<<ETX>>