| Ball and beam system is a experimental teaching equipment designed for automatic control, the electrical engineering, machinery and electronic, and such professional foundation courses, because the Ball and beam system has the characteristics of open-loop instability, we need to design a controller to control the position of the ball. The structure of the system is simple, intuitive and clear, so it can meet the automatic control principle, modern control engineering course’s experiment requirement, and also can act as a motor learning, motor and drag, pattern recognition, etc courses’s laboratory equipment.There are various ways to control the Ball and beam system, it can be realized by the PID control and the root locus control of classical control theory, fuzzy control and neural network control and adaptive control of the modern control theory. Among them, adaptive PID control is widely applied and developed in recent years, because it is easy to control uncertain systems or nonlinear systems, and have strong robustness for parameters changes, and also have a stronger inhibitory ability to outside interference, etc. The purpose of this thesis is to design an adaptive PID controller based on closed-loop characteristic parameters to control the Ball and beam system.This paper analyses the structure characteristics of the Ball and beam system, and the impact of the stability of the system, uses the Newton mechanical equation to establish the mathematic model of the Ball and beam system, and linearization and duly simplified the model to get the discrete model which can easily to calculate by the computer. Then according to the features of time-varying parameters of the mathematical model, we design an adaptive PID controller. In this paper the adaptive PID controller based on the closed-loop characteristic parameters is designed by two loops:inner and outer loop. Inner loop is composed by controlled object and adjustable controller, outer loop is composed by the object parameter recursive estimator and controller design computer.The main part of the two loops is the outer loop, firstly object parameters is estimated by the recursive parameter estimator online, to replace the unknown parameters, then the design institution modify solution to the adjustable controller parameters online according to certain rules, to correct the inner controller, so as to achieve the control purposes of the ball achieve the stability balance positionIn the end we do simulation experiments and research for the adaptive PID controller. We compare the control effect with the traditional PID controller, the results show that this controller has a better control effect. |
