Bifurcation stability of servo-hydraulic systems

Servo-hydraulic systems show significant nonlinear dynamics. Use of bifurcation theory as a tool for design for nonlinearities is a significant development because it provides an inexpensive tool to characterize and classify the dynamical behavior of the system involved. A detailed study of the open-loop and closed loop dynamics of the servo pump-actuator test system is conducted to identify the effect of nonlinearities on the modes of bifurcations of servo-hydraulic systems. The eigenlocus of the test system is computed for various directions in parameter space to investigate the stability behavior. This work involves investigation of the bifurcation behavior in an extended parameter space consisting of both plant and controller parameters, under the assumption of proportional and/or derivative output feedback. Characterization of bifurcation surfaces in parameter space provides information as to the distance and direction to closest bifurcation, thus providing a measure of nonlinear robust stability; the development and application of this methodology in mechanical and hydraulic system applications is the principal long-term goal of this work.