Fault tolerant control for near space vehicle:a survey and some new results

A review on fault-tolerant control（FTC） for near space vehicle（NSV） is presented.First,the concept of near space is introduced,the background of NSV is emphasized,and the model characteristics of NSV in faulty case are investigated.Then,a comparison of different existing approaches is briefly carried out,and achievements on the current research in this field are also presented in the view of the practical application.Furthermore,several existing advanced FTC results for nonlinear flight control systems are given.Finally,the recent literature of NSV are presented to provide an overall view of future developments in this area.

Adaptive sliding mode backstepping control for near space vehicles considering engine faults

A fault tolerant control methodology based adaptive sliding mode(ASM) backstepping is proposed for near space vehicle(NSV) attitude control system under engine faults. The proposed scheme combined adaptive backstepping with the sliding mode control strategy could guarantee the system’s stability and track desired signals under external disturbances and engine faults. Firstly, attitude mode description and the engine faulty model are given. Secondly, a nominal control law is designed.Thirdly, a sliding mode observer is given later in order to estimate both the information of engine faults and external disturbances. An adaptive sliding mode technology based on the previous nominal control law is developed via updating faulty parameters. Finally,analyze the system’s fault-tolerant performance and reliability through experiment simulation, which verifies the proposed design of fault-tolerant control can tolerate engine faults, as well as the strong robustness for external disturbance.

Attitude tracking control for variable structure near space vehicles based on switched nonlinear systems

An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle （VSNSV） in the presence of uncertainties and disturbances. The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online. To improve the flight robust performance, robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation. Moreover, a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control （DSC） approach. According to the common Lyapunov function theory, it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller. The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.

DSC-backstepping based robust adaptive LS-SVM control for near space vehicle’s reentry attitude

Purpose–The purpose of this paper is to propose a robust control scheme for near space vehicle’s(NSV’s)reentry attitude tracking problem under aerodynamic parameter variations and external disturbances.Design/methodology/approach-The robust control scheme is composed of dynamic surface control(DSC)and least squares support vector machines(LS-SVM).DSC is used to design a nonlinear controller for HSV;then,to increase the robustness and improve the control performance of the controller.LS-SVM is presented to estimate the lumped uncertainties,including aerodynamic parameter variations and external disturbances.The stability analysis shows that all closed-loop signals are bounded,with output tracking error and estimate error of LS-SVM weights exponentially converging to small compacts.Findings-Simulation results demonstrate that the proposed method is effective,leading to promising performance.Originality/value-First,a robust control scheme composed of DSC and adaptive LS-SVM is proposed for NSV’s reentry attitude tracking problem under aerodynamic parameter variations and external disturbances;second,the proposed method can achieve more favorable tracking performances than conventional dynamic surface control because of employing LS-SVM to estimate aerodynamic parameter variations and external disturbances.

Adaptive Sampling for Near Space Hypersonic Gliding Target Tracking

For modern phased array radar systems,the adaptive control of the target revisiting time is important for efficient radar resource allocation,especially in maneuvering target tracking applications.This paper presents a novel interactive multiple model(IMM)algorithm optimized for tracking maneuvering near space hypersonic gliding vehicles(NSHGV)with a fast adaptive sam-pling control logic.The algorithm utilizes the model probabilities to dynamically adjust the revisit time corresponding to NSHGV maneuvers,thus achieving a balance between tracking accuracy and resource consumption.Simulation results on typical NSHGV targets show that the proposed algo-rithm improves tracking accuracy and resource allocation efficiency compared to other conventional multiple model algorithms.

Shock wave standoff distance of near space hypersonic vehicles

The shock wave standoff distances of near space hypersonic vehicles, which execute missions mainly at the altitude of 25 km to 55 km, are vital in aerothermodynamic analysis. The implicit finite volume schemes are derived from axisymmetric Navier-Stokes equations for chemical equilibrium flow, and programmed in FORTRAN. Taking a sphere cone for example, the effects of Much numbers （from 22 to 36） on the shock wave standoffdistance and the average density behind the shock are simulated at different altitudes from 25km to 55km. The numerical results illustrate that the turning point of the standoff distance is corresponding to that of the average density with the variation of Mach numbers. Based on the numerical results, we propose a formula for shock wave standoff distance, which is the function of the radius of the blunt body, the Mach number and the altitude in the atmosphere. Compared with previous correlations, the new formula can overcome the drawbacks of larger relative errors and complex calculations of the average density.

Fractional-Order Proportional-Integral-Derivative Linear Active Disturbance Rejection Control Design and Parameter Optimization for Hypersonic Vehicles with Actuator Faults

The hypersonic vehicle model is characterized by strong coupling,nonlinearity,and acute changes of aerodynamic parameters,which are challenging for control system design.This study investigates a novel compound control scheme that combines the advantages of the Fractional-Order Proportional-Integral-Derivative(FOPID)controller and Linear Active Disturbance Rejection Control(LADRC)for reentry flight control of hypersonic vehicles with actuator faults.First,given that the controller has adjustable parameters,the frequency-domain analysis-method-based parameter tuning strategy is utilized for the FOPID controller and LADRC method(FOLADRC).Then,the influences of the actuator model on the anti-disturbance capability and parameter tuning of the FOLADRC-based closed-loop control system are analyzed.Finally,the simulation results indicate that the proposed FOLADRC approach has satisfactory performance in terms of rapidity,accuracy,and robustness under the normal operating condition and actuator fault condition.

Polynomial networks based adaptive attitude tracking control for NSVs with input constraints and stochastic noises

This paper proposes a backstepping technique and Multi-dimensional Taylor Polynomial Networks(MTPN)based adaptive attitude tracking control strategy for Near Space Vehicles(NSVs)subjected to input constraints and stochastic input noises.Firstly,considering the control input has stochastic noises,and the attitude motion dynamical model of the NSVs is actually modeled as the Multi-Input Multi-Output(MIMO)stochastic nonlinear system form.Furthermore,the MTPN is used to estimate the unknown system uncertainties,and an auxiliary system is designed to compensate the influence of the saturation control input.Then,by using backstepping method and the output of the auxiliary system,a MTPN-based robust adaptive attitude control approach is proposed for the NSVs with saturation input nonlinearity,stochastic input noises,and system uncertainties.Stochastic Lyapunov stability theory is utilized to analysis the stability in the sense of probability of the entire closed-loop system.Additionally,by selecting appropriate parameters,the tracking errors will converge to a small neighborhood with a tunable radius.Finally,the numerical simulation results of the NSVs attitude motion show the satisfactory flight control performance under the proposed tracking control strategy.