Robust feedforward tracking servo system for optical disk recording system

This paper proposes a new robust feedforward tracking control system for optical disk recording system, which is based on both "zero phase error tracking" (ZPET) control and a robust feedback control using disturbance observer and coprime factorization. Optical disk recording systems must have a quick and precise tracking control whose error is less than 0.1 μm for a position reference with amplitude of 100 μm. For this purpose, optical disk recording systems should be regulated by feedforward control and robust control. However, the detection signal is only a tracking error and the position reference cannot be obtained. Therefore, this paper proposes a new estimation method of the position reference by using only tracking error, and realizes a quick and precise tracking control based on feedforward control and robust control