Model Predictive Contrl For Hybrid Systems And Its Application In Formation Flying Vehicles

With the development of information technology and computer, many new research objectives appear in control engineering practice and these objectives bring about many challenges for automatic control theory. In recent years, hybrid systems have been widely investigated by many scholars. Hybrid system is a complex system consists of contiuous dynamics and discrete evolution and their interactions. The hybrid system theory includes systematic modeling, analysis and synthesis etc. In this dissertation, some recent results on hybrid systems are reviewed. Then, optimal control technique of the hybrid systems is studied and applied to the formation flight of multiple Unmanned Aerial Vehicles(UAVs).This dissertation first analyzes and reviews the recent developments and some important issues on hybrid system theory. In this part, the basic knowledge of hybrid systems and model predictive control is given, which enriches the context and increases the readability of this dissertation.Secondly, the models of discrete hybrid automata(DHA), piecewise affine(PWA) and mixed logical dynamical(MLD) are established. Each model has its own utility. DHA model can be used to model and simulate hybrid systems. PWA model is commonly utilized to control and stabilize the system. Usually, the MLD model is applied to system control and fault diagnosis. Based on MLD model, the optimal controllers are designed by solving multi-parametric model predictive control.Finally, The receding horizon control method is adopted to design the optimal controller, and this approach is applied to the formation flight of multiple UAVs. The cellular automata are given to plan the optimal path, and then hybrid Lyapunov functions method is proposed to design the optimal controller for each UAV. All UAVs can not only follow the planned path and avoid obstacles but also keep a certain given shape. So-called hybrid Lyapunov function consists of two different functions:(1) a Lyapunov-like function used to guarantee the convergence of the discrete state of finite state machine to a given target point in finite-time,(2) a local control Lyapunov function designed to ensure the stability of the continuous UAV dynamics. By combining the two different functions in a proper manner, it can relax some restraints on the control Lyapunov function and lead to a less conservative result.