Research Of Temperature Control System Based On Nine-Points Controller

Temperature is an important parameter in the industry of steel, machine and so on. Commonly, temperature control means adjusting the temperature of a given space to an expected value to meet the demand of producing process. In the past, it often been controlled with traditional means. This thesis attempts to use a new control theory-Nine-Points controller in the temperature control to enrich the temperature control technology. The object been controlled is electrical oven.Electrical oven is a temperature target, which has time delay, inertia and invariable parameters. Zhang Nanlun, professor of Wuhan University of Technology, present the Nine-Points controller arithmetic. This arithmetic adopts different control actions to attain demand based on the phase plane which is made up of the system of error and the rate of error, based which the phase plane is divided to nine zones. These zones are called work conditions and every work condition has various control strategy which equal to the P of PID controller. Lots of experiments have proved that this means work well in some linear system and some non-linear system.In this thesis, the Nine-Points controller theory is detailed, and based on this theory it design an electrical oven controller. The controller includes main controller module, input signal collection and transformation module, output signal module, man-machine interface module and so on.The main controller is an eight bits Single Chip Microcomputer C8051F020. Temperature signals are collected by a platinum resistance. Output module is actually temperature control module and the temperature is controlled by a two-way controllable silicon. Man-machine interface is designed for a non-coding keyboard and an OCM12864-4 LCD module. Software is designed based on the real time embedded operating system-μC/OS-Ⅱ. Firstly transplant the RTOS to C8051F020, then write the applications.Experiments prove that the temperature controller can successfully adjust the electrical oven's temperature to an expected value. Compared to the temperature controller together with the electrical oven, the controller based on Nine-Points controller have a shorter rising time, and stabilization is better. This result indicates that the Nine-Points controller has a great applied prosperity.