| As electronic technology, computer control, hydraulic control and sensor technology, entered the era of the robot mechanical engineering, mechanical engineering robot as a new member of the family has been shaped, international project known as robots. Wheel loader is running on behalf of the mode of operation of construction machinery, the major consumption of energy in the course of operations and transmission device. Use automatic transmission, the transmission system can achieve the goal of energy saving. Process control equipment for the spade, it will allow work to achieve the goal of energy saving devices. The objective of this paper is to build a engineering robot automatic test -bench for undergraduate and graduate students to do experiments, also in light of the actual situation and theoretical analysis and mathematical modeling. intelligent control technology combined with electro-hydraulic proportional control technology, the hydraulic control system applied to the working device, hydraulic system with a view to overcome the inherent nonlinearity parameter variability arising from the adverse effects of performance, improve performance, achieve the control objectives.Engineering robot test-bench is driven by hydraulic and typical computer-controlled electro-hydraulic control system. At present, electro-hydraulic switch control, electro-hydraulic proportional control and electro-hydraulic servo control are three kinds of hydraulic control system in real application. And different system choose different component as its core. Proportional valve is a kind of hydraulic component between switch valve and servo valve. It's cheaper and more anti-polluting than servo valve. And its performances are as good as servo valve's except precision and response speed. Its static and dynamic characteristic can meet the needs of most of industrial control system. Compared with classic on-off valve, though proportional valve is more expensive, its good control performance made some compensation. So we use proportional valve in those occasion where high control qualities are needed in stead of switch valve. Besides, proportional valve has the function of hybrid control of flow, pressure and direction. All these factors make proportional valve control system has better control performance and more simple structure than classic switch valves.Considering the factors of synthesis performance requirement and cost, we choose the electro-hydraulic proportional valve system as the working device of engineering robot test-bench. The purpose of the study in this thesis is to find a suitable control strategy to improve the performance of the hydraulic position servo system.Chapter 1 summarizes the existing researches on autonomous conducted by other researchers, outlines the basic principles in conventional and intelligent control, briefly describes the basic concept and development of engineering robot history focus on the control of electro-hydraulic control and intelligent control in the application These provide a theoretical foundation for this research.Chapter 2 describes the electro-hydraulic proportional control technology control theory. The proportion of computer-controlled electro-hydraulic control system for position control system design, the optical encoder, and the proportion of the electromagnetic valve amplifier, and given the whole control system test bench components.Chapter 3 based on the analysis of the characteristics of system components, a mathematical model through reasonable simplification is built. We analyze the related parameters and system performances of the electro-hydraulic control system. At the research of control system, it is extraordinary important to build system mathematical model. It is a strong tool to design system, analysis system performance and improve system structure. At the same time pointed out that electro-hydraulic proportional position control system is a nonlinear, time-varying, nonlinear parameters system.Chapter 4 focuses on the variations in the system's parameters which are characteristic of non-linearity and vary with the work conditions. Much work is carried out with the Proportional plus Integral plus Differential (PID) control strategies for the system. PID control, as a kind of control method in automatic control, PID is the most widely used controller due to its functional simplicity and robust performance in a wide range of operating conditions .Based on PID control's structure, the need of practical control engineering and the realizable conditions, special advantages. Test-bench control interface is established by using visual programmable aids VC++ which is an excellent product of Microsoft Corp. According to the incremental mode PID control algorithm, the control program for test-bench is compiled with the help of VC++. The system includes serial communication, Real-time data acquisition and show. Use ActiveX technology to transfer data to Excel tables.Chapter 5 research on control strategy is a very important part in this thesis. In which feasibility is validated by simulation. A fuzzy controller is designed for the system and its robustness is proved. The problem of slow motion in fuzzy control systems is analyzed through simulation. Based on conventional PID control and fuzzy control, fuzzy-intelligent PID hybrid control is adopted as the strategy to keep a good dynamic process and a better steady-state behavior. The simulation results prove that the presented method is reliable and effective. The expected control performance is obtained. The application of fuzzy logic inference well represents the characteristics of human operators in decision-making: qualitative, linguistic, and insensitive to the noise exiting in sensor data. This ensures that these strategies can produce stable control output in fast changing environment.Chapter 6 describes the process and results of simulation with PID controller, fuzzy controller and fuzzy-intelligent PID hybrid control, explores the way of improving control performance through simulation to the PID controller's parameters. The simulation results show that this system works well. This control policy has good real-time performance, quick response, little overshoot and electro-hydraulic proportional position control system with higher performance is obtained. It also proves that the expected purpose is realized.Chapter 7 gives conclusions, contributions of this research, and suggested future work for this topic. |
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