Robust and adaptive control of a beam deflector

A DC-motor driven beam-deflector is to be controlled such that the beam moves with constant velocity for 12 ms out of a 20-ms period before swinging back to the original position. One control system must serve any deflector without retuning. The problem is difficult because the dynamics vary from one deflector to another. It is found that a closed-loop system with poles in a Bessel filter configuration will satisfy the specifications. A straightforward pole-placement design is insufficiently robust. Redesigning it yields greater, but still insufficient, robustness against the known extent of plant parameter variation. The problem is solved by adding an adaptive control loop