In this article, a general structure for the adaptive backstepping scheme based on invariant manifolds has been discussed. Based on this scheme, the flight control system for a small UAV is designed to track the command trajectory of the angle of attack, the sideslip angle, and the roll angle. The adaptive control scheme consists of an estimator and a controller which are separately designed. The estimator which is used to estimate the unknown aerodynamic coefficients on-line relies on the notion of the invariance of the manifold. The estimator consists of a partial estimate generated by an update law and a nonlinear function. The update law and non-linear function are selected so that the dynamics of the estimation error has a stable zero equilibrium, which also guarantees that the defined manifold is invariant. Once the estimate is confined to the manifold, it converges to its true value. The estimator can be exploited by combining it with the backstepping control law. The stability and convergence properties of the control law can be proved using the Lyapunov stability theory. The control law is derived by driving the Lyapunov function negative. This scheme is much easier to tune compared with the classical adaptive flight control law. Furthermore, this approach does not suffer from the undesired transient performance resulting from the unexpected dynamical behavior of parameter update laws. The flight control system based on the proposed method is valid in the entire flight envelope and designed based on a primitive aerodynamic model, which would greatly improve the performance of the flight control system and reduce the cost of the flight control design. The numerical simulation demonstrates that the proposed adaptive flight control law can accomplish the satisfactory command tracking in spite of there being some unknown aerodynamic parameters.


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    Title :

    Non-linear flight control for unmanned aerial vehicles using adaptive backstepping based on invariant manifolds


    Contributors:
    Zhang, Jiaming (author) / Li, Qing (author) / Cheng, Nong (author) / Liang, Bin (author)


    Publication date :

    2013


    Size :

    12 Seiten, 6 Bilder, 34 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English