Servomechanism Design Techniques and Applications

Transistorized alternating current servomechanism design offers a number of advantages over other types because of their small size, low weight, high reliability, precision accuracy, and wide range of control. These lecture notes describe a cryogenic oxygen flow control servomechanism subsystem typical for an auxiliary power unit fuel system. Three possible types of feedback for this type of subsystem are: position feedback accomplished by gear tiain and synchro-transformer, position with velocity feedback accomplished by adding a rate generator and position feedback with compensating network. Servomechanisms employing any of these three types of subsystems can provide the oxygen flow control desired. The differences in performance relate primarily to steadiness of flow with the companion heat modulation. The damping ratio parameter can be used to achieve a reasonable response time and maintain a reasonable value for overshoot. Low damping ratio gives fast response but large overshoots. High damping ratios give low overshoot but slow response. This paper discusses transistorized servomechanism design for the basic position servo, plus rate feedback or network compensation. Included are design and application considerations, step-by-step design procedures, and the solution to sample design examples