Reference model generation using time-varying feedback for model-following control and application to a hard disk drive

Model-following control is one of the control methods widely used in systems that must follow a desired trajectory. One of the difficulties in the method is how to define the desired trajectory that minimizes the time to reach to the target position as well as the minimization of the residual vibration. Methods using sinusoidal signals or polynomial functions of time have been proposed for the reference trajectory generation, however they are sometimes complex, not flexible for different targets, and have long computation times. This paper describes a simple method using time-varying feedback to generate the signals for the model. Simple time-varying feedback is applied to a second-order model using a formula that generates smooth signals of higher order polynomial functions of time. This approach is also applicable to cases where there is a limit on the maximum control signal. Using this method, smooth seek operations in a hard disk drive were demonstrated.