Modeling and identification of spool dynamics in an industrial electro-hydraulic valve

Approximate models of spool dynamics are proposed to deal with dynamic delays observed for an industrial electro-hydraulic valve. The suggested model consists of a linear block and two static nonlinearities. A method for identification of parameters is suggested that allows to deal with a case when only pressure in a hydraulic cylinder is measured but not the displacement of the spool. The approach is verified experimentally.