Dynamic Redesign of a Flow Control Servo-Valve Using a Pressure Control Pilot

In this paper, the dynamic performance of an unconventional two-spool flow control servo valve using a pressure control pilot is analyzed. Such valves are less expensive than typical servo-valves but also tend to be limited in their dynamic performance. Based on a previously developed eight state nonlinear model, we develop a simplified linear model which is able to capture the essential dynamics of the valve. Using root locus analysis method, the limitation in dynamic performance is shown to be due to a “zero” introduced by the structure of the interconnection of the subsystems. Design parameters that move the “zero” further to the left half plane, and do not adversely affect other steady state criteria are identified. The effectiveness of these parameters to improve the dynamic performance is demonstrated.