| The Common pressure rail system(CPR)greatly improves the transmission efficiency of the hydraulic system by regulating the secondary components to deliver energy to the load and recover the negative load energy.As the key component,the hydraulic transformer(HT)plays a vital role in the system energy saving.The integrated hydraulic transformer(IHT)has the advantages of small volume,light weight and high efficiency,which has great advantages and broad application prospects in energy saving.However,due to its special structure and working principle,it has strong nonlinear coupling characteristics,and the conventional control algorithm is difficult to work,which restricts the improvement of system energy saving and control performance.(1)On the basis of consulting and sorting the relevant research data,the development history and research status of HT are summarized.In view of the integrated transformer is the mainstream of the current research on HT,the research results of integrated hydraulic transformer system control are summarized.(2)This thesis focuses on the working principle of the integrated hydraulic transformer.Based on the structure,the displacement,flow,torque and other motion characteristics of the HT are analyzed.Additionally,the composition of hydraulic system based on HT is introduced,and its four quadrant working characteristics are explained.In this thesis,the quantitative motor is selected as the control object,and the hydraulic motor control system based on HT is constructed.Then the dynamic model of the inner and outer loop of the system is established by using the flow continuity equation and force balance equation.According to the working principle and control characteristics of the system,the overall model of the outer loop control system of the hydraulic motor based on the hydraulic transformer is optimized,and the simulation analysis of the inner and outer loop control system is carried out.(3)Based on the analysis of the nonlinearity and control characteristics of the inner loop system,a robust controller is designed for the system,which is combined with the design of extended state observer(ESO)and dynamic surface.Secondly,the finite time design method is used to guarantee the faster error convergence speed and smaller tracking error.The design of dynamic surface and error compensation signal are introduced to effectively solve the differential explosion problem of the system,and compensate the filtering and observation errors.The simulation results show that the designed controller has better performance than the PID.(4)According to the pressure of main oil source,the system is divided into two kinds,the servo system with constant pressure and the servo system with variable pressure.Robust controllers are designed for the servo system respectively.When the oil pressure is constant,the Pi-sigma fuzzy neural robust control algorithm based on finite time command filtering is proposed.The controller designed not only solves the strong nonlinear coupling problem of the system,but also makes the system have stronger robustness and faster error convergence speed under the premise of normal and efficient operation.When the oil pressure changes with the system states,i.e,the hydraulic transformer control system is based on the active pressure regulating CPR system.A finite time robust control algorithm based on barrier Lyapunov functional(BLF)is proposed,so that the control system not only has good error convergence performance,but also has good performance without violating the constraints Strong robustness.(5)Based on the composition of the hydraulic system and the requirements of the experiment,a valve-controlled swing motor position tracking experimental platform is built by reasonably selecting the hydraulic components and measurement and control components.Moreover,a measurement and control integrated controller is constructed by using the Simulink Real-Time tool of MATLAB.Finally,the experimental results verify the superior performance of the controller. |
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