Minimum Effort Hydraulic System Regulation
The British University in Dubai (BUiD)
An investigation into the electrohydraulic performance of long- stroke, loaded, spool valve-controlled, high-pressure, cylinder type servomechanism is presented herein. In addition to spool valve, a needle valve is also included in the hydraulic system so as to create oil leakage across the piston. The leakage flow across the piston is considered so as to produce damping to piston motion. To accommodate performance requirements; single input–multiple output modeling and regulation is proposed. In the study, oil compressibility, the inertia in piston motion and the state equations derived in linearized form are considered. PQR technique is used to derive the transfer function of the open loop system. The applied voltage on the spool and needle valves is considered the single input, while the load position and the leakage flow across the piston are considered as the multiple out-puts. Minimum effort is obtained by optimizing the pole locations of the single input – multiple output system. Optimum locations of the poles are determined by using root locus method and by creating a controller generated zero. The responses are analyzed according to two cases; when the volumes of the cylinder chambers are equal and when they are unequal. Simulation of output responses is shown in order to determine how far the volumes can be considered so as to validate output responses. The control technique used in the application dissipates minimum energy minimizing heat generation, wear and maintenance cost.
hydraulic system regulation, electrohydraulic performance