Obstacles to achieving high-performance servo-tracking using conventional digital-controller designs

Effective real time control decisions in servo tracking problems require maximum use of real time information about the current dynamic behavior of uncertain servo commands, plant disturbances and parameter perturbation effects. That information is embodied in the real time measurements of servo commands and plant outputs but is not explicitly identified and utilized in conventionally designed digital servo controllers, thereby resulting in closed loop performance limitations for such controllers. Those limitations are described in detail and illustrated by a worked example with simulation results. A new approach to digital servo controller design, currently under development, which can significantly reduce those limitations is outlined and demonstrated by a reworking and resimulation of the same example, using the new controller design