Abstract
This paper is concerned with a method of designing the preview controller of the robust servo-mechanism for a discrete linear time invariant system subject to a reference input which is the output of linear free system, named reference system.
It is assumed that the controller can make use of preview information with respect to all states of reference system from the present time upto l time units in the future. The optimal preview control problem is formulated as that of minimizing a quadratic performance index in the infinite period.
It is revealed that the controller can be designed under certain condition for the case that the reference system has some instable modes and we can always design it for reference inputs such as polynomial and sinusoidal type ones which may be considered to be important in practical use. Moreover, it is proved that the optimal performance index of the designed control system is uniquely evaluated.
An example is presented to show that the preview action improves the performance of the control system.
