Hybrid Control On An Electro-Hydraulic Proportional Position Control System

An electro-hydraulic proportional position control system (EHPPCS) with a single-rod hydraulic actuator is a nonlinear and time-variable system. The variations in the system's parameters are characteristic of non-linearity and vary with the work conditions. Much work is carried out with the modern control strategies for the EHPPCS. Not only stability and fast dynamic response of the position control system are studied, but also the speed of the hydraulic actuator during the process of dynamic response. The dynamic performance of the EHPPCS is greatly improved and the purpose of the hybrid control is also achieved. Furthermore, the speed control of VVVF hydraulic elevator is studied using PID control law and numerical simulations are carried out with the Simulink of Matlab. The sealing performance of the reciprocating seals on an axial piston is investigated in both Navier-Stokes equations and finite element method. The reduction of noise for hydraulic axial piston pump is studied and two invention patents have been received.In chapter 1, the history and current research status of the EHPPCS are introduced based on a lot of the publications and conference papers. And the author put forward that stability and fast dynamic response of the position control system are studied, while the speed of the hydraulic actuator during the process of dynamic response is studied. The research aim and significance are described.In chapter 2, The experiment rig is set up, the EHPPCS with computer control is designed, and position signals, speed signals and pressure signals are introduced in details. Experiments are carried out to study the friction and wear performance for the materials of piston and cylinder in a water hydraulic axial piston pump. Sealing performance of the reciprocating seals on a larger diameter axial piston is investigated. The novel methods to reduction of noise are introduced for hydraulic axial piston.In chapter 3, mathematical models are derived for the EHPPCS, computational simulations are carried out using PID control, adaptive control, robust control and adaptive robust control respectively in toolbox Simulink of Matlab. The simulation results are analyzed and The plant model of the EHPPCS is given.In chapter 4, experiments are carried out using PID control, adaptive control, robust control and adaptive robust control respectively under the conditions of different pressures, different temperatures with disturbances and without disturbances. The experimental results are discussed, compared and analyzed. Computational simulation and experimental research on VVVF hydraulic elevator speed control is carried out.In chapter 5, based on the experiments, overall analysis and comparisons are carried out for the control performance of the EHPPCS through measuring the inlet pressure, outlet pressure and pressure difference of an electro-hydraulic proportional valve. The fast response, anti-interference performance, steady-state performance and even speed of the actuator are discussed with disturbances and without disturbances.In chapter 6, some conclusions are given and some new views are put forward in the future.