Part I: Modeling of a One-Degree-of-Freedom Active Hydraulic Mount

There is a diverse range of applications for active hydraulic mounts such as vibration absorbers, flight simulators, and industrial test rigs. The purpose of the mount considered here is to make a mass that is driven by an external force and a hydraulic actuator behave as if it were a prescribed mechanical impedance driven solely by the external force. We develop a model of this mount that includes the effects of servovalve dynamics and fluid compressibility and will be used in the future design of a robust control system. Then the conic sector bound method, which is readily amenable to the application of established robust control methodologies, is used to describe a family of linear time-varying plants that could be used to represent the nonlinear behavior of the system.