The Digital Hygrothermal Environment Testing System For Vehicle Lamps Based On Fuzzy PID

With the rapid development of automobile industry in China, automobile market competition became more and more intensely, Caused people to the tireless pursuit of quality products more. Faced with the reality of survival of the fittest,Seek only high-quality, high-standard products to take in the fierce competition victory。The product of rigorous testing to become an important guarantee for the quality of products in the production process。As the lighting instructions components, vehicle lamps play an important role at safety drive as well as vehicle performance. Similarly, in the production process of the vehicle lamps, make a rigorous test to the lights of the overall confined, coating part of the technical indicators become an important tool to measure and protect the quality of products.This paper comes from the engineering project, to research and develop a digital hygrothermal environment testing system for vehicle lamps. The system is mainly used for constant temperature measurement and test based on the obturation of the vehicle lamps and the capability of the coating in the lamps. For this system, confined environment me closer to guarantee a 100% RH (70℃) humidity, to meet the technical requirements of systems, the design of this major is for the temperature control and regulation。To solve the problem that temperature control may do the regulation of a long time and a large quantity of overshoot in hygrothermal environment system, raised a new mode including on the use of fuzzy control and PID (proportional, integral, differential) control as a control of the joint, that is use the fuzzy control arithmetic in the tuning parameters of the PID control. Avoid the deficiencies when using one separate temperature control method. A Fuzzy-PID controller which have high response speed and steady-state accuracy have been designed. Apply to the hardware circuit design, form a complete monitoring system for the vehicle lamps of the hygrothermal environment measuring and testing. The details are as follows:(1) Conducting extensive literature to read, understand the relevant technical information, the combination of engineering projects initiated under the contents of the design work at the same time to write papers. First introduction the main contents and source of research on automotive lamps test system in hygrothermal environment, such as the theory and engineering significance of the developments in the field of temperature control, also gave an overview of the status quo.(2) Use the fuzzy control arithmetic in the tuning parameters of the PID control, construct the fuzzy rule tableand the temperature curve simulation, through the simulation results , we can easily see, fuzzy PID controller is more batter than conventional PID controller. Thereby , it has a relatively short period of time and a smaller increase overshoot, further proved the feasibility of theory.(3) Make theoretical research basis for the entire system of software development and hardware design, Conduct research, choose STC89C52 SCM, Design fuzzy PID controller, temperature acquisition a smart temperature sensors DS18b20, keyboard display smart chip ZLG7289, a high-speed analog-digital conversion chip design, such as MAX5352. development the digital test system in hygrothermal environment which meet the technical requirements, in this paper there is a more detailed description on the software procedures and hardware circuit design.(4) It is proved that by the actual operation debugging that system is stable and reliable, easy to accurately detect the temperature data as well as control the temperature of hygrothermal environment, reached the Corresponding design standards.To sum up, this paper design for use in hygrothermal environment test system of vehicle lamps, made specific work from theoretical research to the actual circuit developed, and achieved good results. System is very practical and serviceable, and easy to maintain, thus achieving the expected goal. But the system still need to be perfecting the part: To make the temperature measurement to more points, it is necessary to conduct digital temperature sensor software programming and hardware linking the improvement;in the expanded function of the system ,therefore, the learning process in the future will be the function of the system development, hardware design, and do more further study so as to improve the work.