CONTROL SYSTEM DESIGN
Hydraulic valves are extensively employed in the closed-loop position of actuators so as to obtain good steady state accuracy and speed of response. The open-loop velocity control of linear actuators was discussed in Chapter 7, where the flow through the valve, for constant supply pressure, was shown to depend upon the valve opening and the pressure drop across the opening. Thus, under specified pressure conditions, the valve can be used as a flow source when connected to an actuator, the velocity of which will be proportional to the valve opening.
The dynamic performance of a valve actuator system is developed in which it is assumed that the mass of the moving components and the load force ...