Robust Repetitive Control And Its Application To Oil Cooler's Pulsation Fatigue Test-bed

Oil cooler is one of the most important components in Automobile Internal Combustion Engine's lubrication system. It is a device which is used to accelerate the radiation of the lubricant to keep it at low temperature. The operational effect of I.C. Engine is largely depended on the quality of oil cooler.More often than not, oil cooler is working under severe conditions. Therefore it is essential to implement some fatigue tests before oil cooler is used on the real system to ensure that it can work properly. Currently, one of the most widely-used methods is to use electro-hydraulic technology to put such experiments into practice, which simulates various kinds of periodical pressure signals by adjusting the opening of the pressure relief valve. By repeating different types of periodical pressure shocks (sine wave, triangular wave, trapezium wave, etc) on the specimen, the fatigue property of oil cooler could be tested. With the purpose to improve the pressure tracking accuracy and the adaption of the control system, this paper designed an oil cooler's fatigue pulsation test-bed system based on robust repetitive control theory.The main content of this paper is as follows:1. Analyze the main function of oil cooler, the working principle of fatigue pulsation test-bed and the necessity to execute fatigue experiments. Give a brief introduction to the development of electro-hydraulic technology and control strategies adopted in it.2. Introduce the basic principle of repetitive control and robust repetitive control and the methods to design them, clarify the key problems and design strategies of robust repetitive control.3. Determine the design scheme and technical route of the whole system, design the hardware and software environment of the oil cooler's pulsation test-bed according to the concept of DCS, illustrate the working principle of the hardware system and the working process of software system. Analyze the layout of the hardware execution components.4. Propose the mathematical model of the pressure relief valve according to the knowledge of hydraulic and design robust repetitive controller of test-bed based on the proposed model.5. Build up simulation models of PID controller, repetitive controller and robust repetitive controller in Matlab/Simulink environment. Prove the accuracy of pressure tracking of the designed robust repetitive controller by comparing tracking effects of PID controller, repetitive controller and robust repetitive controller. Testify the robustness of the designed robust repetitive controller to parameter variations by modifying the parameter of the pressure relief valve. Confirm the adaption of the designed robust repetitive controller to periodical signal variations by altering the period of input signal and comparing the effects of repetitive controller and robust repetitive controller.6. Summarize the similarity and difference of repetitive control and robust repetitive control in tracking periodical signals according to the comparing results and verify the priority of the designed robust repetitive controller.7. Discrete the designed robust repetitive controller and then fulfill it on the real system by writing program on the computer. Prove the effectiveness of robust repetitive controller.