Air-breathing Hypersonic Vehicle Model Research Articles

Nonlinear Adaptive Equivalent Control Based on Interconnection Subsystems for Air-Breathing Hypersonic Vehicles

For the nonminimum phase behavior of the air-breathing hypersonic vehicle model caused by elevator-to-lift coupling, a nonlinear adaptive equivalent control method based on interconnection subsystems is proposed. In the altitude loop, the backstepping strategy is applied, where the virtual control inputs about flight-path angle and attack angle are designed step by step. In order to avoid the inaccurately direct cancelation of elevator-to-lift coupling when aerodynamic parameters are uncertain, the real control inputs, that is, elevator deflection and canard deflection, are linearly converted into the equivalent control inputs which are designed independently. The reformulation of the altitude-flight-path angle dynamics and the attack angle-pitch rate dynamics is constructed into interconnection subsystems with input-to-state stability via small-gain theorem. For the velocity loop, the dynamic inversion controller is designed. The adaptive approach is used to identify the uncertain aerodynamic parameters. Simulation of the flexible hypersonic vehicle demonstrates effectiveness of the proposed method.

Feedback linearization-based robust nonlinear control design for hypersonic flight vehicles

A new approach to designing a robust nonlinear controller for longitudinal flexible body models of canard configured air-breathing hypersonic flight vehicles with significant couplings and interactions is presented. The methodology uses a robust feedback linearization method to feedback linearize the nonlinear air-breathing hypersonic flight vehicle model with 24 uncertainty parameters. Using this approach, a linearized uncertainty model of the air-breathing hypersonic flight vehicle is obtained in the first step by considering an upper bound on each uncertain parameter. In the second step, a minimax linear quadratic regulator-based velocity and altitude robust tracking controller is synthesized for the linearized model. Simulation studies are conducted using the original nonlinear model of the air-breathing hypersonic flight vehicle with a large flight envelope and time-varying uncertainties. Simulation results show that the feedback linearization-based minimax linear quadratic regulator controller effectively achieves the tracking requirement and robustly stabilizes the air-breathing hypersonic flight vehicle.

Quasi-continuous high-order sliding mode controller and observer design for flexible hypersonic vehicle

The problem of robust output feedback control and simulation for the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV) is investigated in this paper. A control-oriented uncertainty model is established for the feedback linearization design, and the multi-input and multi-output (MIMO) quasi-continuous high-order sliding mode (HOSM) controller is formulated to track the responses of the vehicle to a step change in velocity and altitude based on full state feedback. In addition, a high order sliding mode observer is designed to estimate the angle of attack and the flight path angle, which are difficult to measure in a hypersonic flight. Furthermore, the combination of the HOSM controller and observer is proposed for vehicle model with partial state measurements. The simulation results are presented to verify the effectiveness of the proposed control strategy.

Sampled-data switched control for flexible air-breathing hypersonic vehicles

The nonstandard dynamic characteristics of flexible air-breathing hypersonic vehicles along with the aerodynamic effects of hypersonic flight cause the flight control of such vehicles highly challenging. Additionally, the wide range of speed and the varied parameters make the problem more difficult. In this article, the problem of sampled-data switched output tracking control design is addressed for flexible air-breathing hypersonic vehicles. First, the nonlinear longitudinal model of flexible air-breathing hypersonic vehicles is linearized with respect to different regions, and the switched sampled-data guaranteed cost controller design problem is discussed. Using an input delay approach, the switched system with sampling measurements is transformed into a continuous time-delay system. Then, by a Lyapunov approach, the existence condition of such a controller is developed in the form of linear matrix inequalities. A smooth switching condition is also designed simultaneously, and the sampled-data smooth switching controller design problem is cast into a convex optimization problem. The simulation results are reported to show the effectiveness of the proposed control method.

Nonlinear Controller Design for Hypersonic Vehicles Based on Dynamic Inversion Considering Flexible States

This paper describes a nonlinear adaptive dynamic inversion controller for a flexible air-breathing hypersonic vehicle model. The complete characterization of the nonlinear internal dynamic of the Bolender and Doman model with respect to velocity，altitude and angle as the regulated outputs is considered in this paper. The derivation of the internal dynamics presented in this work is comprehensive of the flexible dynamics. For the purpose of control design，we decompose the equations of motion into functional subsystems，namely，the velocity subsystem，the altitude and flight-path angle subsystem，and the angle of attack and pitch rate subsystem. Each subsystem is controlled separately using available inputs and intermediate virtual control commands. The adaptive fuzzy system is then developed to identify the uncertain in the model parameters. Simulation results are provided to demonstrate the robustness and the efficacy of the proposed controller

Time-varying control via nominal trajectory linearization for an air-breathing hypersonic vehicle

A time-varying control law via nominal trajectory linearization for an air-breathing hypersonic vehicle (ABHV) model is applied. Feasible guidance command signal serials are generated by nonlinear dynamic inverse (NDI) method considering interactions between aerodynamic effects and propulsion systems. Multiple-time-scale continuous time-varying control, which meets the requirement with accurate, robust, and decoupled tracking of both the commanded trajectory and angular rate profiles in the presence of modeling uncertainties and external disturbances are applied. The simulations for an ABHV model with modeling uncertainties, wind gust, and measuring noises are presented to demonstrate the capacity and reliability of this proposed method.

Robust Adaptive Control Based on Specified Region Pole Assignment for Flexible Hypersonic Vehicle

This paper describes a robust adaptive controller based on specified region pole assignment for flexible hypersonic vehicle. The dynamic model of air-breathing hypersonic vehicle retains features including flexible effects, non-minimum phase behavior, model uncertainties, and strong couplings between flight dynamic and engine. To track velocity and altitude commands, robust controller based on specified region pole assignment is used to make unstable modes of open-loop system stable and guarantee dynamic performance of attitude. Meanwhile adaptive controller is proposed to solve tracking problems when existing control failures or saturation. The simulation results demonstrate that the proposed controller achieves excellent dynamic performance while the engine operates normally.

Multi-Objective Fault-Tolerant Output Tracking Control of a Flexible Air-Breathing Hypersonic Vehicle

This paper deals with the problem of multi-objective fault-tolerant output tracking control for the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV). There exist some challenges for control design for the vehicles due to the inherent couplings between the propulsion system, the airframe dynamics, and the presence of strong flexibility effects. This paper addresses the problem of guaranteed cost fault-tolerant output tracking control with regional pole constraints against actuator faults for the FAHV system. A non-linear longitudinal model is adopted for control design because of the complexity of the FAHV systems. First, a linearized model is established around the trim point including the state of altitude, velocity, angle of attack, pitch angle, and pitch rate, etc. for a non-linear, dynamically coupled simulation model of a FAHV with the aim to address the multi-objective fault-tolerant output tracking control problem. Second, the control objective and models of actuator faults are presented. Third, by utilizing the Lyapunov functional approach, a multi-objective analysis condition is proposed in terms of convex optimization problems, that can be easily solved via standard numerical software. Then, a multi-objective fault-tolerant controller is designed such that the resulting closed-loop system is asymptotically stable and satisfies a prescribed performance cost with the simultaneous consideration of poles assignment in spite of possible actuator failure. Finally, the simulation results are given to show the effectiveness of the proposed method, which is verified by an excellent altitude reference and velocity tracking performance.

Nonlinear Robust Adaptive Control of Flexible Air-Breathing Hypersonic Vehicles

This paper describes the design of a nonlinear robust adaptive controller for a flexible air-breathing hypersonic vehicle model. Because of the complexity of a first-principle model of the vehicle dynamics, a control-oriented model is adopted for design and stability analysis. This simplified model retains the dominant features of the higher-fidelity model, including the nonminimum phase behavior of the flight-path angle dynamics, the flexibility effects, and the strong coupling between the engine and flight dynamics. A combination of nonlinear sequential loop closure and adaptive dynamic inversion is adopted for the design of a dynamic state-feedback controller that provides stable tracking of the velocity and altitude reference trajectories and imposes a desired set point for the angle of attack. A complete characterization of the internal dynamics of the model is derived for a Lyapunov-based stability analysis of the closed-loop system, which includes the structural dynamics. The proposed methodology addresses the issue of stability robustness with respect to both parametric model uncertainty, which naturally arises when adopting reduced-complexity models for control design, and dynamic perturbations due to the flexible dynamics. Simulation results from the full nonlinear model show the effectiveness of the controller.