Observer Based Fault Diagnosis For Helicopter Modeled By Linear Parameter Varying Systems

Helicopter flight control system is an important part of the helicopter and plays a crucial role in the helicopter flight performance and safety. The performance and safety of the helicopter are affected by input disturbance and actuator fault, which may lead to an aviation accident in severe cases. It's significant to research the fault diagnosis (FD) and its applications so that the helicopter should be able to attain the best performance in the nominal case and maintain a satisfactory closed-loop system performance in the presence of actuator faults.This dissertation studies the FD against actuator faults under whole or part of the flight envelope based on a linear matrix inequalities (LMIs) approach for helicopter which combines linear parameter-varying (LPV) techniques.Firstly, the history and the development of FD are surveyed. Also the problem of the helicopter FD based on LPV is proposed. Then the basic knowledge of helicopter movement analysis and the establishment of the actuator fault model are introduced. An overview of the LPV system theory is given.All above are the foundation of the following study of FD.Secondly, with respect to actuator fault in helicopter modeled by linear parameter varying (LPV) flight systems, it proposes a fault diagnosis method based on adaptive observer. The observer is designed by use of LPV polytopic structure, applying the parameter-dependent Lyapunov stability condition to the design,and the designed parameters are obtained by solving the linear matrix inequalities (LMIs)constrained convex optimization problem. Finally ,the proposed fault diagnosis method is tested on a LPV helicopter flight control systems, and the simulation results show that the method can estimate the fault effectively.Simultaneously, the method proposed in this dissertation is compared with the classic adaptive fault estimation based on single Lyapunov function in LPV systems, which can significantly enhance the performance of the fault estimation of actuator faults by the simulation results.Also the proposed arithmetic has well dealt with the conservation in latter method,which is more advantagedFinally, the proposed FD method based on a LPV adaptive observer for the LPV control system actuator fault in this dissertation is applied to a 3 Degree of Freedom (DOF) helicopter physics experiment system. For the 3-DOF helicopter model, the fault diagnosis module is designed, and the MALTAB numerical simulation can achieve satisfactory results. Then this designed modules is applied in the actual experiments and the experimental results show that the FD module also can estimate the actuator fault of 3-DOF helicopter system effectually and the arithmetic has some practical application value.