Study Of Control Characteristics Of Hydrostatic Driving Secondary Regulation Technology

Secondary Regulation is a kind of hydrostatic driving technique, which has the ability to realize energy recovery and regeneration with one or several pressure-coupled executive components working in a constant pressure network. It adapts to changes of the external load by adjusting the inclination of the slant plate of a secondary component. Therefore, not only does it possess fairly well dynamic and static characteristics, but also in some conditions, the secondary component can serve as a pump to recover kinetic energy or gravity potential energy. It undoubtedly has expansive application foreground in nowadays. However, the secondary regulation technology still remains many problems in theories and applications to be discovered. In this thesis, taking a secondary regulated torque servo loading equipment as the concrete object, the secondary regulation technology is studied in deep and width.After consulting numerous data home and aboard, firstly, the development of automatic control is surveyed by inducing the functions of various control theories in automation. Secondly, the main problems and research directions in electrohydraulic servo control domain are analyzed. Then, the development and application status of secondary regulation is surveyed with its main problems pointed out. Finally, the research direction of this thesis is determined.In the thesis, the static velocity modifying specialties of a secondary regulated system under alternative load is studied. Under a gravity potential load, a secondary component can realize the working conversion from motor to pump without adjusting its slant plate over zero point, which however gains the energy-saving purpose. The recovered energy is gravity potential energy. Moreover, since the pump-state is in a limitary zone of the slant plate inclination, the peak power of energy recovery can be calculated. Meanwhile, under a constant torque load, a secondary component has to adjust its slant plate over zero point to realize the working conversion from motor to pump. The secondary component has three working states, such as, driving state, driving-reverse state and energy-consuming braking state. It may work in all the four quadrants, but it has no stable working point while working as a pump. The simulation results prove the validity of the above theoretical analysis.The mathematical model of the secondary regulated torque loading equipment is finished, after establishing the models of pressure-constant displacement pump, hydraulic accumulator and secondary component. From the model, it is easy to see that the oil supply system, the rotational velocity system and the torque system are thoroughly interconnected. Coupling exists between the rotational velocity system and torque system, the two systems put a disturbance on the oil supply system in form of loading flow, and inverse the generated pressure fluctuation of the supply forms a disturbance on the velocity system and torque system. Based on the mathematical model, the dynamic stiffness of secondary regulated rotational velocity system is researched with simulating approach, which points out that the inner loop and integral take advantages of increasing the dynamic velocity stiffness of the system.In the thesis, neural optimized TAKAGI-SUGENO fuzzy model control and neural based iterative learning control algorithms are put forward, which have the abilities to adapt system nonlinearity, parameter time-varying and loading disturbance. Moreover, the weighted D (differential) iterative learning control algorithm is studied with some useful deductions found. With respect to the specialty that a loading track can be repeated on the secondary regulated loading equipment, the possibility is discussed on whether the algorithm used on the rotational velocity system.The mechanism of the coupling between the velocity system and torque system is studied in the thesis. Then several methods are put forward to eliminate the coupling from hardware and their merits and shortages are mentioned. On the other hand, a decoupling network for the secondary regulated equipment is designed in the thesis. The network realizes approximately thorough dynamic decouple between the velocity system and torque system from software.In the thesis, all the hardware interface circuits for the equipment are made, and part of the equipment is rebuilt. For the convenience of real use, software with perfect function and friendly interface is worked out for control with Visual C++ under Windows95.A large number of experiments are done on the secondary regulated loading equipment in the thesis. These experiments increase the dynamic and static performances of the equipment.