Study On Variable Structure Control For Two-wheeled Unstable Vehicle

The two-wheeled self-balancing vehicle is a special kind of wheeled mobile robot and a complex system in nature, its dynamic equations are multi-variable, nonlinear, strong coupling, parameter uncertainty and so on. Not only the environment in which the vehicle moves is complicated, but also the task needs to complete is arduous. Therefore, the two-wheeled self-balancing vehicle is an ideal platform for studying variety of control methods. At present, the fuzzy control, optimal control and PID control are commonly used to control the two-wheeled self-balancing vehicle, but the variable structure control is rarely used. In this paper, we use the Variable Structure Controller to control this vehicle system. The work can be listed below.Firstly, though analyzing and studying the model of two-wheeled self-balancing system in home and abroad, we gave the vehicle’s nonlinear model.Secondly, after comparing the condition number of controllability matrix about linear mode obtained around the balanced point based on Taylor series linearized model, fuzzy weighted linearized model and the feedback linearized mode respectively, we got that the feedback linearized model is very approximate to that original nonlinear model.Finally, based on the principle of the linear quadratic optimal controller design, it provides design theory of switching function in variable structure control. Through the simulation, the results show that optimal controller can control of the self-balanced two-wheel vehicle well. At the same time, based on exponential reaching law, the paper designs variable structure regulator; then discretes it, ensuring the vehicle can achieve good steady state. It studies the properties change, finding out the lowest sampling frequency if the bad performance is not obvious, it prepares for the realization of the variable structure method in nonlinear vehicle motion control.