Tracking Control Of Hypersonic Vehicles Research Articles

Performance-prescribed optimal neural control for hypersonic vehicles considering disturbances: An adaptive dynamic programming approach

The precise trajectory tracking control of hypersonic vehicles plays a crucial role in secure flight. To address this challenge, this article develops an optimal neural control framework with prescribed performance constraints for height-velocity control tasks with disturbances. To this end, the control-oriented error model is firstly established and transformed into an affine nonlinear form to provide a foundation for the design of controller. Then, in order to balance performance constraints and convergence speed, a performance-constraint function is introduced to convert the constrained tracking error into an unconstrained one. After that, an improved sliding mode compensation observer is proposed by combining low-fidelity approximation data with high-fidelity compensation model for eliminating disturbances. The developed control scheme is organized by an adaptive dynamic programming (ADP) algorithm based on the actor-critic policy structure to achieve the near-optimal control strategy. Meanwhile, the designed neural network (NN) weight updating laws are provided to obtain the solution of Hamiltonian-Jacobi-Bellman (HJB) equation rapidly without high calculation consumption. Finally, the stability conditions of the closed-loop system are performed and ensure the entire framework is semi-global uniformly ultimately bounded (SGUUB), two simulation cases verify the effectiveness and superiority of the proposed approach.

Attitude tracking control of hypersonic vehicle based on an improved prescribed performance dynamic surface control

AbstractIn this paper, we investigate the constrained attitude control problem of hypersonic vehicles (HVs). An improved prescribed performance dynamic surface control method is proposed based on an adaptive scaling strategy. Because of the uncertain time-varying disturbances, the controlled state may violate the constraint in the prescribed performance control (PPC) framework. An adaptive scaling strategy is introduced in the PPC method to avoid state violation. The performance function is scaled with respect to the state adaptively. Moreover, a nonlinear disturbance observer is used to compensate the sum of external and other internal disturbances of the system. The proposed method improves the system dynamic performance while ensuring the system robustness. Furthermore, the stability of the closed-loop system is proved by Lyapunov analysis. Finally, numerical simulations are implemented to verify the effectiveness of the PPC method and superiority over other methods.

Asymptotic adaptive tracking control for hypersonic vehicles with guaranteeing multi-performance requirements

This paper investigates the tracking issue for hypersonic vehicles with multiple performance requirements, and presents a globally asymptotic adaptive control approach with performance guarantees and robustness against bounded disturbances. The proposed adaptive scheme is inherently established based on the transformed error variables with incorporating the performance requirements, and thus results in the globally asymptotic tracking for hypersonic vehicles with guaranteeing prescribed performance functions. Meanwhile, the fine robustness for the closed-loop system is obtained with no need for any disturbance estimation. The proposed method is applied into the velocity and altitude subsystems and the stability of the overall closed-loop system is analyzed. The numerical simulation results verify the effectiveness of the presented method, and a Monte Carlo campaign is also run to evaluate the behavior of the developed control method.

Trajectory tracking control of hypersonic vehicle considering modeling uncertainty

The tightly coupled, highly nonlinear, and notoriously uncertain nature of hypersonic vehicle dynamics brings a great challenge to the control system design. In this paper, an integrated controller based on Differential flatness theory and L1 adaptive theory is designed, and a nonlinear disturbance observer is added to solve the problem of model uncertainty. Differential flatness is applied to the outer loop to linearize the nonlinear model, and L1 adaptive control is applied to the inner loop to stabilize the attitude. The combination realizes the complementarity of their shortcomings. It can not only retain the advantages of L1 adaptive controller, but also avoid wide range of state changes and makes it easy to design parameters satisfying global convergence. The computational order of differential flatness is also reduced and the design of nonlinear disturbance observer becomes feasible. Simulation results for the hypersonic vehicle are presented to demonstrate the effectiveness and robustness of the proposed control scheme.

Tracking Control of Hypersonic Vehicles with Input Saturation Based on Fast Terminal Sliding Mode

In this paper, the track problem of hypersonic vehicle is studied and analyzed with external disturbances, parameter uncertainty and input saturation. First, to make the design of controller convenient, the input and output linearized high-order model of hypersonic vehicle is transformed into a multi-variable second-order system model by introducing auxiliary error variables. To ensure the sliding mode manifold is practical finite time stable, an adaptive fast nonsingular terminal sliding mode controller is designed for hypersonic vehicle with unknown upper bound of disturbance. An adaptive anti-saturation fast nonsingular terminal sliding mode controller is designed by introducing hyperbolic tangent function an auxiliary system, which further solves the input saturation problem. Not only the requirement for actuator physical restraint is satisfied, but also the finite time stability of system sliding mode manifold is guaranteed at the same time. The vigorous proof is given using Lyapunov theory for the designed controllers. The numerical simulations are also conducted with the longitudinal nonlinear dynamic mode of hypersonic vehicle. The results demonstrate the effectiveness of the two designed controllers.

Fast terminal sliding mode tracking control of hypersonic vehicles based on non-homogeneous disturbance observer

The tracking control problem of hypersonic vehicles is studied and analyzed in this paper using terminal sliding mode control method (TSMC) and non-homogeneous disturbance observer(NHDO) considering parametric uncertainty and external disturbances. Non-singular terminal sliding mode controller is provided based on NHDO. The key idea is that the NHDO is adopted to estimate the aerodynamic uncertainties and external disturbances simultaneously, which can enhance the robustness of the system and lower the gain of the switch controller. Rigorous stability analysis for the closed-loop system is given via Lyapunov stability theory, which proves that the system states are always bounded even during the estimation process when the estimation error is not zero. The sliding manifold can be reached in finite time and the tracking errors can converge to zero asymptotically. Numerical simulations are conducted with the longitudinal nonlinear dynamic model of hypersonic vehicles to verify the effectiveness and robustness of the designed controller.

Finite-time tracking control of hypersonic vehicle with input saturation

This paper studies the finite-time tracking control problem of hypersonic vehicle in presence of model parameter uncertainties, external disturbance and input saturation. Firstly, to cope with the unknown upper bound disturbance of the system, an adaptive fast terminal sliding mode controller is designed based on a non-homogeneous disturbance observer (NHDO) which can alleviate the chattering and make the proposed controller strongly robust. Meanwhile, a new saturation function is introduced to solve the singular problems of the controller. Secondly, to further solve the problem of input saturation, the hyperbolic tangent function and auxiliary system are introduced to design an anti-saturation fast adaptive terminal sliding mode controller which not only can satisfy the requirements of the actuator's physical limitation, but also guarantees that the sliding mode manifold is finite-time stable. Finally, Lyapunov theory is used to prove the stability of the designed controller strictly, and the numerical simulations of the longitudinal model of the hypersonic vehicle are carried out, which further confirm the robustness and effectiveness of the two designed controllers.

Tracking Control of Hypersonic Vehicle Considering Input Constraint

AbstractThis paper studies the tracking control problem of hypersonic vehicles under the circumstances of external disturbance, coupling response, and input constraint. First, on the basis of the i...

Disturbance observer-based L1 robust tracking control for hypersonic vehicles with T-S disturbance modeling

This article concerns a disturbance observer-based L1 robust anti-disturbance tracking algorithm for the longitudinal models of hypersonic flight vehicles with different kinds of unknown disturbances. On one hand, by applying T-S fuzzy models to represent those modeled disturbances, a disturbance observer relying on T-S disturbance models can be constructed to track the dynamics of exogenous disturbances. On the other hand, L1 index is introduced to analyze the attenuation performance of disturbance for those unmodeled disturbances. By utilizing the existing convex optimization algorithm, a disturbance observer-based proportional-integral-controlled input is proposed such that the stability of hypersonic flight vehicles can be ensured and the tracking error for velocity and altitude in hypersonic flight vehicle models can converge to equilibrium point. Furthermore, the satisfactory disturbance rejection and attenuation with L1 index can be obtained simultaneously. Simulation results on hypersonic flight vehicle models can reflect the feasibility and effectiveness of the proposed control algorithm.

Disturbance observer based robust mixed H2/H∞ fuzzy tracking control for hypersonic vehicles

This paper introduces a disturbance observer (DO) based mixed H2/H∞ robust fuzzy tracking control design for the longitudinal dynamics of a generic hypersonic vehicle (HV) with modeled and unmodeled disturbances. A Takagi–Sugeno (T–S) fuzzy model is firstly employed to approximate the nonlinear dynamics of HV. Subsequently, based on the fuzzy model, a DO is constructed to estimate the modeled disturbance. Next, by integrating the HV dynamics, the tracking error integral and the disturbance estimation error dynamics, an augmented system is established for the control design. Then, a DO-based mixed H2/H∞ robust fuzzy control design is developed to ensure the asymptotic stability as well as the mixed H2/H∞ control performance of the augmented system. The proposed control scheme includes a fuzzy tracking controller with state feedback plus the tracking error integral, a robust nonlinear compensator for eliminating the matched part of the compound disturbance consisting of the unmodeled disturbance and fuzzy modeling error, and a DO-based compensator for the modeled disturbance cancellation. The outcome of the DO-based mixed H2/H∞ robust fuzzy control problem is formulated in terms of linear matrix inequalities (LMIs). Furthermore, by utilizing the existing LMI optimization technique, a suboptimal controller is obtained in the sense of minimizing an upper bound of H2 performance. Finally, simulation results on an HV demonstrate the effectiveness of the proposed design method.

Continuous sliding mode controller with disturbance observer for hypersonic vehicles

In this paper, a continuous sliding mode controller with disturbance observer is proposed for the tracking control of hypersonic vehicles to suppress the chattering. The finite time disturbance observer is involved to make that the continuous sliding mode controller has the property of disturbance rejection. Due to continuous terms replacing the discontinuous term of traditional sliding mode control, switching modes of velocity and altitude firstly arrive at small regions with respect to disturbance observation errors. Switching modes keep zero and velocity and altitude asymptotically converge to their reference commands after disturbance observation errors disappear. Simulation results have proved the proposed method can guarantee the tracking of velocity and altitude with continuous sliding mode control laws, and also has the fast convergence rate and robustness.

H∞ based decoupling tracking control of hypersonic vehicle

The H∞ based decoupling tracking control is studied in this paper. A virtual system constituted by the controlled system and the no coupling reference model is firstly set up. The controlled system is driven to follow the reference model to realize the decoupling. And the tracking error can be formulated by the H∞ norm of the virtual system. Then the controller is derived by minimizing the H∞ norm, which can be described by Linear Matrix Inequalities (LMIs). The necessary and sufficient condition of existence of controller is derived based on the LMIs above. A flight control example is given to illustrate the effectiveness of the proposed method. The simulation results show that the proposed method is of better control performance than Linear Quadratic (LQ) tracking controller.

Non-certainty equivalence adaptive tracking control for hypersonic vehicles

The design of a novel non-certainty equivalence adaptive control system for hypersonic vehicles is presented, based on the immersion and invariance (I&I) theory. The interest here is to achieve a robust trajectory tracking of the reference commands in spite of large parameter uncertainties. The architecture of the whole control system is constructed by decomposing the vehicle model into the velocity subsystem and the flight path angle (FPA) subsystem. A backstepping design procedure is applied to the cascaded FPA subsystem. Three non-certainty equivalence controllers, each consisting of a control module and an I&I based parameter estimator, are designed respectively for the velocity subsystem and the two steps of the FPA subsystem, which suffer from parameter uncertainties. First-order filters are implemented in all the design of the three controllers to avoid solving certain partial differential inequality in I&I adaptive control. Stability analysis is presented using Lyapunov theory and asymptotical convergence of the tracking errors to zero is accomplished. Simulation results with rapid and accurate command tracking show the effectiveness and robustness of the proposed control system.