Qun Zong

Continuous high order sliding mode controller design for a flexible air-breathing hypersonic vehicle.

This paper investigates the problem of tracking control with uncertainties for a flexible air-breathing hypersonic vehicle (FAHV). In order to overcome the analytical intractability of this model, an Input-Output linearization model is constructed for the purpose of feedback control design. Then, the continuous finite time convergence high order sliding mode controller is designed for the Input-Output linearization model without uncertainties. In addition, a nonlinear disturbance observer is applied to estimate the uncertainties in order to compensate the controller and disturbance suppression, where disturbance observer and controller synthesis design is obtained. Finally, the synthesis of controller and disturbance observer is used to achieve the tracking for the velocity and altitude of the FAHV and simulations are presented to illustrate the effectiveness of the control strategies.

Real-Time Trajectory and Attitude Coordination Control for Reusable Launch Vehicle in Reentry Phase

The real-time reentry trajectory and attitude coordination control for a reusable launch vehicle (RLV) is a very important and challenging problem. There are many aspects that make the research appealing, such as being able to autonomously replan a new trajectory onboard when the landing site is changed. In order to achieve the goal, an integrated guidance and control architecture is proposed in this paper. First, the offline reentry trajectory is designed based on adaptive Gauss pseudospectral method. Then, the obtained trajectory is used as the initial value guess for real-time reentry trajectory optimization. As a result, the pseudospectral-based optimal feedback reentry guidance is achieved via successive real-time optimal open-loop control which ensures that the guidance system has sufficient robustness for initial reentry perturbations. Furthermore, a multitime scale smooth second-order sliding-mode controller with disturbance observer is proposed to ensure the finite-time reentry attitude tracking despite the model parameter uncertainties and unknown external disturbances. Finally, two representative simulation tests are carried out to demonstrate the effectiveness of the proposed integrated guidance and control architecture for six-degree-of-freedom RLV.

Robust adaptive backstepping tracking control for a flexible air-breathing hypersonic vehicle subject to input constraint

This paper presents a tracking control problem of flexible air-breathing hypersonic vehicle with input constraint and aerodynamic uncertainty. Without ignoring aero-propulsive and elevator-to-lift couplings, a control-oriented model including aerodynamic uncertainty is firstly established. Then a robust adaptive backstepping control scheme is designed, in which the control-oriented model does not need to be transformed into linear parameterization formulation. Upper bounds of the uncertain terms do not need to be known in advance, which are estimated online by designing robust adaptive laws. To further consider input constraint, a constrained robust adaptive backstepping controller is proposed to simultaneously handle input constraint and aerodynamic uncertainty. Finally, the compared simulation results show the effectiveness of the designed control strategy.

Nonlinear robust control for reusable launch vehicles in reentry phase based on time-varying high order sliding mode

Abstract This paper describes the design of nonlinear robust controller for reusable launch vehicles which is nonlinear, multivariable, strong coupling, and includes uncertain parameters. Firstly, the feasible guidance strategy is proposed to obtain the desired guidance commands. Then, the time-varying sliding mode manifold is designed through calculating a series of algebraic equations with fixed final states to make the system trajectories start on the manifold at the initial time. The global robustness is ensured via designing high order sliding mode attitude controller which forces the system trajectory to stay on the sliding mode manifold despite the model parameter uncertainties and external disturbances. Furthermore, in order to reduce control saltation, the virtual control is introduced into the control strategy. Finally, the six degree of freedom flight simulation results are provided to demonstrate the effectiveness of the integrated guidance and control strategy in tracking the guidance commands as well as achieving safe and stable reentry flight.

Robust adaptive approximate backstepping control of a flexible air-breathing hypersonic vehicle with input constraint and uncertainty:

This article shows the controller design problem of a flexible air-breathing hypersonic vehicle in the presence of input constraint and aerodynamic uncertainty. A control-oriented model, derived from curve-fitted model, is reasonably decomposed into subsystems that include velocity subsystem, altitude and flight path angle subsystem and angle of attack and pitch rate subsystem. Then, dynamic inversion and robust adaptive control are integrated with approximate backstepping control philosophy to design the control scheme, in which the upper bounds of uncertainties are not to be known in advance and estimated by adaptive law. To tackle input constraints, auxiliary systems are constructed and the states of them are used for controller design and stability analysis. Moreover, a detailed stability analysis of the resulting rigid body system is carried out within the framework of Lyapunov theory. Finally, simulation results illustrate the property of the designed control strategy in handling input constraint and aerodynamic uncertainty.

Flight control for a flexible air-breathing hypersonic vehicle based on quasi-continuous high-order sliding mode

The focus of this paper is on control design and simulation for the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV). The model of interest includes flexibility effects and intricate couplings between the engine dynamics and flight dynamics. To overcome the analytical intractability of this model, a nominal control-oriented model is constructed for the purpose of feedback control design in the first place. Secondly, the multi-input multi-output (MIMO) quasi-continuous high-order sliding mode (HOSM) controller is proposed to track step changes in velocity and altitude, which is based on full state feedback. The simulation results are presented to verify the effectiveness of the proposed control strategy.

Robust Adaptive Approximate Backstepping Control Design for a Flexible Air-Breathing Hypersonic Vehicle

AbstractThis paper presents a tracking control problem of a flexible air-breathing hypersonic vehicle with aerodynamic uncertainty. The flight control design is challenging because of heavily coupled propulsive, aerodynamic forces and flexibility effects. A control-oriented model is derived where the flexible dynamics are regarded as perturbations and the aerodynamic uncertainty is included. It does not need to be transformed into a linear parameterization formulation. Based on an analysis of it, it is decomposed into a velocity subsystem and an altitude subsystem. Then dynamic inversion and a sliding mode control are combined to design the controller of the velocity subsystem. In addition, the sliding mode control and adaptive control are incorporated into a backstepping control architecture to develop the controller for the altitude subsystem after it is transformed into approximately strict-feedback form. The upper bounds of the uncertain terms do not need to be known in advance. They are estimated onl...

Disturbance observer–based dynamic surface control design for a hypersonic vehicle with input constraints and uncertainty

This article presents the flight control problem of a flexible air-breathing hypersonic vehicle under input constraint and aerodynamic uncertainty. First, a control-oriented model is derived and decomposed into velocity subsystem and altitude subsystem, in which compounded disturbances are included to consider aerodynamic uncertainty and the effect of the flexible modes. Second, nonlinear disturbance observer technique is employed to estimate the compounded disturbance, where the estimation error converges to a compact set if the observer design parameters are chosen appropriately. Then, based on disturbance observer, a robust controller and a dynamic surface controller are developed, respectively, for the velocity subsystem and the altitude subsystem. Third, novel robust first-order filters are designed to overcome the “explosion of terms” problem induced by backstepping method. Additional systems are constructed to tackle input constraints. By rigorously Lyapunov stability proof, the designed control strategy can assure that tracking error converges to an arbitrarily small neighborhood around zero. Finally, simulations are performed to show the effectiveness of the presented control strategy.

Multivariable Finite Time Attitude Control for Quadrotor UAV: Theory and Experimentation

The attitude control of quadrotor unmanned aerial vehicle (UAV) is investigated. The aim of this paper is to develop a continuous multivariable attitude control law, which drives the attitude tracking errors of quadrotor UAV to zero in finite time. First, a multivariable super-twisting-like algorithm (STLA) is proposed for arbitrary order integrator systems subject to matched disturbances. A discontinuous integral term is incorporated in the control law in order to compensate the disturbances. A rigorous proof of the finite time stability of the close-loop system is derived by utilizing the Lyapunov method and the homogeneous technique. Then, the implementation of the developed method in an indoor quadrotor UAV is performed. The remarkable features of the developed algorithm includes the finite time convergence, the chattering suppression and the nominal performance recovery. Finally, the efficiency of the proposed method is illustrated by numerical simulations and experimental verification.

Adaptive Backstepping Finite Time Attitude Control of Reentry RLV with Input Constraint

This paper presents the finite time attitude tracking control problem of reusable launch vehicle (RLV) in reentry phase under input constraint, model uncertainty, and external disturbance. A control-oriented model of rotational dynamics is developed and used for controller design for the complex coupling of the translational and rotational dynamics. Firstly, fast terminal sliding mode control is incorporated into backstepping control to design controller considering model uncertainty and external disturbance. The “explosion of terms” problem inherent in backstepping control is eliminated by a robust second order filter. Secondly, the control problem in the presence of input constraint is further considered, and a constrained adaptive backstepping fast terminal sliding mode control scheme is developed. At the control design level, adaptive law is employed to estimate the unknown norm bound of lumped uncertainty with the reduction of computational burden. The Lyapunov-based stability analysis of the closed-loop system is carried out. The control performance is presented via the simulation of six-degree-of-freedom (6-DOF) model of RLV.