Research On Nonlinear Adaptive Fault-tolerant Control Method Based On DSC For Hypersonic Vehicles

As hypersonic vehicle has the feature of fast speed,easy recycling,so it has vast application prospect in military affairs and civilian use.But hypersonic vehicle model has the trait of high nonlinearity,this not only bring forward big challenge to the design of controller,but also make high request for the maneuvering characteristics of actuator.And the frequent maneuver will also increase the malfunction of system actuating element/sensor components.In order to elevate viability of aerial craft in the malfunction so as to decrease catastrophic damage,it is of great significance to enhance the research of fault tolerant control technology of hypersonic vehicle.This article mainly introduces three aspects of hypersonic vehicle fault-tolerant control successively.Considering the attitude model of hypersonic vehicle suffering with actuator faults,parameter perturbation and external disturbance,an adaptive nonlinear fault-tolerant control(FTC)method is addressed to assure the tracking ability of the flight system.Firstly,a back-stepping based fault-free controller is proposed where norm estimation approach are combined with fuzzy adaptive approach to approximate the model uncertainties,which observably reduces the computation burden of multi-parameter identification.Then,on the basis of the fault-free controller,a compensation controller is designed to handle the partial loss fault of actuator effectiveness,where the unknown maximum eigenvalue of actuator efficiency loss factors is estimated online.While the partial loss fault become serious,the above designed compensation controller will be saturated by the amplitudes of actuator,which will lead to the instability of control system.Therefore,considering the longitudinal model of hypersonic vehicle suffering with damage fault,control input saturation and parameter uncertainties,a novel FTC controller is proposed base on the Nussbaum gain technology.To solve the actuator input saturation nonlinearity,the hyperbolic tangent function is introduced to approximate the input saturation function,and the mean-value theory is then used to help design the controller.In the controller,the unknown functions are approximated by fuzzy adaptive technique where the norm estimation method is introduced to minimize the enormous adaptive update laws toone.And the Nussbaum gain method is used to avoid the possible singularity phenomenon or system instability caused by the unknown gain function or unknown fault gain.Considering the craft suffered with stuck fault and damage fault,a novel fault tolerant control approach is approved for the two-piece elevator aircraft model.In the approach,the remained available control input is used to compensate for the effect caused by the stuck one,and the norm estimation method based on fuzzy adaptive technique is used to approximate the faulty function.What more,the Nussbaum gain technique is again used to handle the damage fault.