Research And Experiment Of PID Parameter Stable Region For Time-delay System

In industrial processes, there exist time delays in different degrees. It is difficult to control a process with time delay. The larger the percent of time delay in the whole dynamic process, the more difficult to control it. Therefore, stabilizing controller parameter of a time-delay system is important for process control. The open-loop transfer function of an industrial process is often described as a first-order process with time delay.PID controllers have become one of the basic control schemes and are widely used in industry control because of their simple configuration, clear functions and strong robustness. The paper based on a graphical stability criterion in parameter space, the stabilizing region of PI parameters was discussed for first-order processes with dead-time, and this kind of design method was extended to the case of achieving the given phase and gain margins. The graphical stability criterion adopted here releases a necessary and sufficient stability condition for dead-time processes, and the results obtained have no any conservatism. The boundary curves of stabilizing region and the phase and gain margin curves could be drawn directly in parameter space. The practical algorithms for determining the stabilizing region and the phase and gain margins are given. Then use the graphical approach to PID, based on a graphical stability criterion in parameter space, the range of proportional-gain is given. For both stable and unstable open-loop plants, the stabilizing region in integral derivative space is plotted and determined directly, not to be calculated mathematically.In the concrete experiment aspect, this topic uses AT89S52 single chip which has the high performance-to-price integrated time-delay observation system's hard core, and simulate time-delay object, including stable object and unstable object. Then uses the RS-485 agreement, realizes the data transfer, receives processing by Kingview software of the superior machine. The single chip integrated circuit uses the nixietube demonstration the exchange data of closed-loop system, demonstrates the curve with the configuration with Kingview contact surface. This system has many functions such as collecting signal, analyzing trends, also it can execute dynamic management of supervisory parameter, create report forms automatically, and it can be rectified and expanded easily.