Optimum Linear Preview Control With Application to Vehicle Suspension

The concept of preview control (a control scheme in which an input is sensed before it reaches the controlled plant) is discussed and applied to the guidance of vehicles over statistically described surfaces. Two methods are presented for optimizing the trade-off between vehicle vibration and the clearance space required for excursions of a vehicle relative to a roadway. The first approach, based on Wiener filter theory, is used to synthesize the optimum characteristics (transfer function) of a free-configuration system. Since the transfer function synthesized in this manner is very difficult to mechanize, a parameter-search technique is used to optimize a fixed-configuration system which may be more easily realized in practice. The results of this study show the reduction in vibration and clearance space that a preview control system may bring about as compared to an optimized system that does not use preview information. Preview control may account for root-mean-square vibration reduction by as much as a factor of sixteen at constant clearance space or a decrease in clearance space by a factor of $223$ at constant vibration level.