This brief presents the general guidelines for design, testing, identification and validation of electro-hydraulic actuation system. An analytical procedure for sizing the
system for given loading and actuation rates has been elaborately explained. The
system size is projected in terms of actuator capacity, servo valve flow rating, pump
capacity and motor capacity. To verify the system design, the flow rates and system
pressure values from experimental data have been compared with those from analytical
calculations. The system performance in closed-loop operation is measured by comparing commanded position with the actual position. The flapper nozzle servo valve
acting as direction control valve forms the core component of this system. As an
attempt to provide a one-stop solution in completely understanding the working and
dynamics of the valve, elaborate mathematical modelling is carried out from first
principles and governing equations. However, due to OEM propriety, the servo valve
internal parameters are not disclosed to the end-user. Thus, to identify the servo valve
internal parameters, system identification approach has been adopted. A step-by-step
approach for building mathematical models from experimental data using system
identification toolbox (MATLAB) has been presented. The mathematical models built
using first principles and through system identification are simulated, and the results are
verified with the experimental results.
The brief is arranged in the following chapters: Chap. 1 lays out analytical approach
to size the system in terms of load and flow rate calculations; Chap. 2 presents
mathematical models of the flapper nozzle type direction control servo valve; Chap. 3
gives an insight into servo valve performance plots; Chap. 4 introduces the concept of
system identification and lays out the procedure for identification and implementation;
Chap. 5 presents simulation and test results followed by the conclusion in Chap. 6.