Final-State Control Using Polynomial and Time-Series Data

For information devices such as hard disk drives, actuators must be controlled quickly and precisely as much as possible. To satisfy these requirements, feedforward input design is very important. For this problem, we have proposed a frequency-shaped final-state control method. This method can obtain a feedforward input that has lower spectrum at desired frequency points so as to reduce residual vibration after positioning. Furthermore, the method has been extended to generate the feedforward input by a polynomial. By using the polynomial, the required memory size can be drastically reduced because it only requires to store the coefficients of polynomial. However, in the frequency-shaped final-state control method by polynomial input, it is not guaranteed that the solution always exist theoretically. In order to solve this problem, final-state control methods in which the feedforward input is generated by both of a polynomial and time-series data are proposed. The effectiveness of the proposed methods are verified by simulation using the plant model of the HDD benchmark problem. The simulation results show that the proposed method outperform the conventional methods.