Research On Fuzzy Control For Double Inverted Pendulum

Inverted pendulum is a typical high order system that is fleet, multivariable, nonlinear, strong coupling and absolutely instable. The research on theories and methods of the inverted pendulum's control is of extensive significance in many fields such as walking of biped robots, launching process of rockets and flying control of helicopters. Several fuzzy control strategies are employed to solve the contradiction between the control performance and the number of fuzzy rules, aiming to control double inverted pendulum effectively in this thesis.Firstly, the development situation and trend of fuzzy control are discussed briefly and the development course and research status of inverted pendulum are summarized in this thesis. The structure and work principle of double inverted pendulum are introduced. Nonlinear mechanism model of it and its linearization model in equilibrium are obtained by means of Lagrange equation. Performances, such as stability, are analyzed for linearization model.Secondly, linear quadratic optimum control, fuzzy control, and their mutual combination are discussed systematically. Several fuzzy control strategies are studied. Information fusion which is based on fuzzy control strategy reduces the dimension of its input vectors and solves the problem of rule number's explosion by combining the linear system theory with information fusion technique. Takagi-Sugeno based gradual fuzzy control strategy, which has fewer and more effective rules and can greatly simplify the design process of fuzzy controller, is adopted to stabilize the double inverted pendulum.Finally, the simulation model of double inverted pendulum system is edited by compiling S function in Matlab/Simulink and some simulations are carried out. Simulation results indicate that the fuzzy control strategies proposed in this thesis can not only solve the problem of fuzzy rule number's explosion and simplify the design process of fuzzy controller, but also obtain better performance in control of the double inverted pendulum.