The Analysis of Valve-Controlled Hydraulic Servomechanisms

Since the development of hydraulic control valves such as that employed in the Nike missile, emphasis has been given to the analysis of hydraulic phenomena in valved systems, with much of the literature having been devoted to hydraulic component design. In this paper, the nonlinear closed-loop performance is given major emphasis; the effect, of hydraulic parameter variations on the closed-loop frequency and transient responses is examined by linear and nonlinear methods. The basic servomechanism under consideration in this study, as shown in Fig. 1, consists of a summing device, an amplifier, a flow source and control system, a hydraulic actuator (or motor) and a load. In the following sections, the nonlinear differential equations which represent the behavior of this closed-loop system are derived, a linear and an incremental-linear representation are discussed and solutions of the nonlinear equations obtained by analog computation are compared with linear solutions. 1 2,3,4 In this section, emphasis is on the derivation and validity of the equations used to represent the behavior of the actuator and load; the mechanization of the flow source and its method of control will be discussed in detail in the following section. 1513