Research On Aerodynamic Surface Fault Estimation And Self-healing Control For Hypersonic Flight Vehicles

When the hypersonic flight vehicle is flying in the near space,several physical components such as elevators and rudders may malfunction because of the high speed,low pressure and strong convection environment.The high cost of research and development of hypersonic vehicle also means that the failure of flight test will cause immeasurable loss of property.Therefore,the self-healing control of hypersonic flight vehicle under actuator faults is highly significant.The fault estimation(FE)problems of longitudinal model and attitude system of hypersonic flight vehicles are studied in this paper,respectively.And several corresponding self-healing control methods are developed based on the fault estimation results.The main research content is as follows:(1)A fault estimation observer and a fault tolerant controller are designed for hypersonic flight vehicle with elevator faults based on type-2 fuzzy adaptive theory.An interval type-2 Takagi-Sugeno(T-S)fuzzy model for the hypersonic flight vehicle system with elevator faults is first developed.An improved interval type-2 T-S observer-based fault estimation algorithm is then proposed for each subsystem to enhance the estimation speed,and gain parameters are obtained via linear matrix inequalities.The estimation results from the given fuzzy observer are used to design a type-2 fuzzy fault accommodation controller to stabilize the fuzzy system.The stability of the proposed scheme is analyzed using the Lyapunov stability theory.(2)A multiple-step adaptive iterative fault estimation algorithm is developed to relax the fault estimation condition and reduce the impact of external disturbances on fault estimation.The external disturbances are added to the interval type-2 T-S fuzzy model of hypersonic flight vehicle to make the model more representive.A multiple-step adaptive fault estimation algorithm is disegned to estimate the unknown additive fault,the estimation result from each step is used for the next estimation part.Such kind of “iteration” is helpful to enhance the estimation accuracy in the presence of external disturbances.(3)A self-healing control scheme is proposed for hypersonic flight vehicle with body flap faults based on nonsingular terminal sliding mode and dynamic surface control theory.For outer angular loop,refer to professor Sun's work,a terminal sliding mode controller for attitude angular loop is introduced to obtain the virtual control input.Thus,the required deflection angle of aerodynamic surfaces can be calculated via adaptive dynamic surface technique in inner angular rate loop.When the aero-surfaces are saturated and unable to supply the moment vector commanded by the fault tolerant controller,10 reaction jets will be driven by quadratic programming allocator to provide the residual control torque.The attitude tracking performance can be guaranteed with the designed fault-tolerant controller(4)Interval type-2 fuzzy technique and cuckoo search algorithm are adopted to improve the control scheme.The unknown input perturbation and additive faults are estimated together via interval type-2 fuzzy estimator.To improve the utilization efficiency of aerodynamic surfaces,linear quadratic programming and cuckoo search algorithm are combined to allocate the desired control torque to eight aero-surfaces.With the given scheme,the torque generated by aero-surfaces can match the desired control moment as much as possible,while saving the system fuel and ensuring that the attitude angle can track the given attitude angular command.A series comparative simulation for different scenarios is conducted for the developed fault estimation algorithm and self-healing control schemes.The proposed control scheme can effectively compensate for the actuator fault while accurately obtaining the fault information.Thus,the system stability and tracking performance can be guaranteed.