Graphical Approach To Stable Margin Desing Of Pid Contoller For Time-delay System

PID control algorithm is by far the most common control strategy. There are many different ways to determine appropriate controller parameters. These methods are distinguished from complexity, mobility and the use of process knowledge. A good setting method should be based on reasonably considering the compromise of the following characteristics:load disturbance attenuation, measurement noise effect, process change robustness, setting value changes, the response of the model, computation requirements, etc. We need simple, intuitive and easy methods; these methods need less information, and will be able to make the appropriate performance. We also need those complicated methods that can obtain good performance, although they need more information and computation.For time-delay plants, utilizing PID controller, the design problem of guaranteeing gain-margin and phase-margin is discussed in this dissertation. Based on the gain-phase margin tester technique, in the stability region of PID controller, the gain-margin curve and the phase-margin curve are plotted, respectively. Furthermore, the regions satisfying the given gain-margin and phase-margin are identified in terms of a graphical stability criterion applicable to time-delay systems. Simulation examples show that the PID control system designed via the method in this dissertation has a better control effect both in robustness and dynamic response aspects. Graphic approach to determine the stability of the PID controller parameter domain and the design of the stability margin, do not need to complicated mathematical calculation, can be implemented directly by system simulation method, the method is easy and simple, and can be applied to any controlled objects with or without time-delay, have certain universality and engineering significance. In the feasible region, other performance optimization, such as phase margin and amplitude margin, can find out to meet the corresponding indicator set of PID controller parameter regions, thus can greatly improve the efficiency of the design of the controller. This method can be applied to the majority of industrial control systems, and provides a simple and efficient design method for industrial control system controller design.