Mathematical models for time-domain design of electrohydraulic servomechanisms

IN THE ANALYTICAL DESIGN of high-speed electrohydraulic servomechanisms, an accurate mathematical model of the valve-actuator mechanism is generally helpful in determining the controller and system configuration required to achieve the desired over-all performance. During past years, various forms of electrohydraulic valves and actuator mechanisms have been realized. Detailed descriptions of these devices can be found in a book by Blackburn et al.1 Most previous works on the analysis of these systems have resorted to linearization techniques.2,3 Recently, Butler and Turnbull presented detailed analysis of simplified nonlinear models.4,5 Also, Zaborszky and Harrington derived describing functions for both single and two-stage electrohydraulic valves, which permit analytical design in the frequency-domain.6¿9 The limitations of linearized models are discussed by Rausch.10