The Synthesis Of Robust Flight Control System For UAV

Robust flight control system design for unmanned aerial vehicles (UAV) is studied in this paper. The main works are described as follows.The synthesis techniques for multi-objective H₂/H_∞ control and its flight control system based on linear matrix inequality (LMI) is discussed. State feedback controller is designed with external interference and modeling errors are considered. Compared to H₂ and H_∞ control methods, multi-objective H₂/H_∞ controller has stronger robustness, smaller control gain and wider application domain. An example of flight control simulation is given to illustrate proposed method.A blended PID/H_∞, robust and minimum-energy flight control system is studied. First, the H_∞ robust controller satisfying quadratic stability and a minimum-energy index constraint is studied. External disturbance and the parameter uncertainties both in system matrix and control matrix are considered. By some transformations, the solution is converted to a standard H_∞ control problem, and the feedback gain matrix can be easily obtained by solving a Riccati equation. Then a new robust flight control structure, which still includes two loops, is presented. The inner loop controller is designed to reject external disturbance and system parameter uncertainties based on our approach under interval model system description. The traditional PID controller is used in the outer loop. Three designed flight operation states of a UAV are selected in the simulation for performance comparisons. The results shows that the new flight control system has very little overshoots and shorter setting-time than the traditional one, at the same time without no more control effort requirements.