Generic Hypersonic Vehicle Model Research Articles

Adaptive fault tolerant control for hypersonic vehicle with input saturation and state constraints

This paper proposes an adaptive control scheme for hypersonic vehicle with external disturbances, parametric uncertainties, actuator failures, input saturation and state constraints. Firstly, the longitudinal model of generic hypersonic vehicle is divided into velocity subsystem and altitude subsystem. Secondly, based on the tangent barrier Lyapunov function and auxiliary system, two adaptive fault tolerant controllers are designed for velocity subsystem and altitude subsystem, respectively, which can solve the problem of input saturation. By using the controllers, the flight states containing the angle of attack, flight path angle, pitch angle and pitch angle rate can be guaranteed in prospective ranges. Finally, the Lyapunov stability theory and numerical simulations are adopted to verify the effectiveness of the presented controllers.

${\mathcal{L}}_{1}$ adaptive control augmentation for a six-degree-of-freedom hypersonic vehicle model

In this paper, we present the design of an ${\mathcal{L}}_{1}$ adaptive control augmentation system for a six-degree-of-freedom generic hypersonic vehicle model. We focus on addressing system uncertainties, which lead to undesired performance if not properly addressed in the control design. The design begins with the development of a nonlinear dynamic inversion system as the inner-loop controller, which achieves linearization between system inputs and outputs. Linear feedback controllers are then designed as a baseline control system. In addition, the ${\mathcal{L}}_{1}$ adaptive control architecture is used to develop augmentation setups to enhance the control performance of the baseline controllers in the presence of system uncertainties and disturbances. The simulation results demonstrate that the proposed augmentation scheme improves the overall control performance and enhances the robustness of the control system.

Low-order diving integrated guidance and control for hypersonic vehicles

A novel low-order integrated guidance and control (LOIGC) design model is deduced, and an original diving integrated guidance and control design approach is proposed in this paper. An analytical model between three-channel body rates and components of acceleration of the hypersonic vehicle in the ballistic frame is derived, and the commanded body rates can be directly obtained by analytic calculation. The LOIGC design model is conducted based on three dimensional (3D) relative dynamics between the hypersonic vehicle and target, and the direct relation with respect to line-of-sight (LOS) angles and control surface fin deflections of the hypersonic vehicle is established. Based on the LOIGC model, the design of six-degree-of-freedom (6DOF) guidance and control system for diving hypersonic vehicles can be converted into an output tracking problem of a low-order nonlinear system, and the commanded control surface fin deflections can be directly obtained by controlling derivatives of elevation and azimuth angles of line-of-sight between the hypersonic vehicle and target. In this paper, the system order and tuning parameters of the 6DOF guidance and control system are both decreased, and the design procedure of 6DOF guidance and control system is simplified. The process of calculating commands of angle of attack and bank angle based on desired guidance overloads, and the tracking loops with respect to Euler angles and body rates of the rotational system can also be omitted. In addition, the newly proposed method can improve the utilization of velocity measurements in the body frame of the hypersonic vehicle. Finally, the effectiveness and robustness of the newly proposed integrated guidance and control design approach are verified and investigated using a 6DOF generic hypersonic vehicle model.

Adaptive fault tolerant control for hypersonic vehicle with external disturbance

In this article, an adaptive fault tolerant control strategy is proposed to solve the trajectory tracking problem of a generic hypersonic vehicle subjected to actuator fault, external disturbance, and input saturation. The longitudinal model of generic hypersonic vehicle is divided into velocity subsystem and altitude subsystem, in which dynamic inversion and backstepping are applied, respectively, to track the desired trajectories. For the unknown maximum disturbance upper bound, actuator fault, and input saturation constraint, adaptive laws are proposed to estimate these information online. Finally, numeric simulation is conducted in the cruise phase for generic hypersonic vehicle. Simulation results show that the controllers designed in this article can make generic hypersonic vehicle track the desired trajectories in the presence of actuator fault, external disturbance, and input saturation.

Sequential Loop Closure Based Adaptive Output Feedback

This paper presents a new, systematic method of synthesizing an output feedback adaptive controller for a class of uncertain, non-square multi-input/multi-output systems. The control design process consists of first designing an inner-loop controller for a reduced order plant model to enforce command tracking of selected inner-loop variables, with an adaptive element used to accommodate parametric uncertainties in the plant. Once this inner-loop control design is complete, an outer-loop is then designed, which prescribes the inner-loop commands to enforce command tracking of selected outer-loop variables. The main challenge that needs to be addressed when designing the inner-loop controller is the determination of a corresponding square and strictly positive real transfer function. This is accomplished by appropriate selection of two gain matrices that allow the realization of such a transfer function, thereby allowing a globally stable adaptive output feedback law to be generated. The outer-loop controller is designed around the plant with existing adaptive inner-loop controller such that global stability of the closed-loop system is guaranteed. The design of the outer-loop uses components of a closed-loop reference model in a judicious manner which enables a modular approach, without requiring any re-design of the inner-loop controller. In addition, this architecture facilitates the use of an additional state-limiter to enforce desired limits on the state variables. A numerical example based on a scramjet powered, generic hypersonic vehicle model is presented, demonstrating the efficacy of the proposed control design.

L 1 adaptive control of a generic hypersonic vehicle model with a blended pneumatic and thrust vectoring control strategy

The extreme aeroheating at hypersonic regime and the insufficient dynamic pressure in the near space limit the achievable performance of the hypersonic vehicles using aerosurfaces alone. In this paper, an integrated pneumatic and thrust vectoring control strategy is employed to design a control scheme for the longitudinal dynamics of a hypersonic vehicle model. The methodology reposes upon a division of the model dynamics, and an L1 adaptive control architecture is applied to the design of the inner-loop and outer-loop controllers. Further, a control allocation algorithm is developed to coordinate pneumatic and thrust vectoring control. Simulation results demonstrate that the allocation algorithm is effective in control coordination, and the proposed control scheme achieves excellent tracking performance in spite of aerodynamic uncertainties.

Adaptive Output Feedback Based on Closed-Loop Reference Models for Hypersonic Vehicles

This paper presents a new method of synthesizing an output feedback adaptive controller for a class of uncertain, nonsquare multi-input/multioutput systems that often occur in hypersonic vehicle models. The main challenge that needs to be addressed is the determination of a corresponding square and strictly positive real transfer function. This paper proposes a new procedure to synthesize two gain matrices that allow the realization of such a transfer function, thereby allowing a globally stable adaptive output feedback law to be generated. The unique features of this output feedback adaptive controller are a baseline controller that uses a Luenberger observer, a closed-loop reference model, manipulations of a bilinear matrix inequality, and the Kalman–Yakubovich lemma. Using these features, a simple design procedure is proposed for the adaptive controller, and the corresponding stability property is established. The proposed adaptive controller is compared to the classical multi-input/multioutput adaptive controller. A numerical example based on a scramjet-powered blended-wing/body generic hypersonic vehicle model is presented. The six-degree-of-freedom nonlinear vehicle model is linearized, giving the design model for which the controller is synthesized. The adaptive output feedback controller is then applied to an evaluation model, which is nonlinear, coupled, and includes actuator dynamics; and it is shown to result in stable tracking in the presence of uncertainties that destabilize the baseline linear output feedback controller.

Flight Dynamic Characteristic Analysis of a Generic Airbreathing Hypersonic Vehicle

Because of the high speed, strong coupling between aerodynamics and propulsion system, complex environmental conditions and new propulsion system, the airbreathing hypersonic vehicles have a complex dynamics characteristic. This paper use the generic hypersonic vehicle model (CSULA-GHV) to research this issue. The nonlinear longitudinal equations of motion are linearized based on the assumption of little perturbation. Analyze the dynamic characteristic on a feature point selected. The results show that, the stability of this model is poor. It has to design an efficient controller to adjust the poor stability.

Ascent trajectory planning on-board based on direct optimisation method

In this paper, an on-board trajectory planning algorithm is proposed for atmospheric ascent. To deal with the impact of disturbance, the on-board trajectory planning algorithm updates the reference trajectory by solving an optimal control problem on-board. Considering the strong non-linear aerodynamic, the optimal control problem is transformed into non-linear programming problem by trajectory discretisation. The direct optimisation method is implemented for this non-linear programming problem. Due to the small amount of discrete nodes and the initial guess solution which is close to the optimisation solution, the direct optimisation method is fast enough to generate a new reference trajectory in every guidance cycle. With different cases of the aerodynamic coefficient bias, numerical simulation for the generic hypersonic vehicle model and scramjet engine is done. The results show the accuracy and the effectiveness of the on-board trajectory planning algorithm.