Nonlinear Output Feedback Designs
In this chapter, we address adaptive output feedback actuator failure compensation control for nonlinear systems with uncertain actuator failures. In Section 11.1, the actuator failure compensation control problem is formulated for for the class of output-feedback systems. An adaptive state observer for output feedback control is proposed in Section 11.2. Combined with the state observer, an adaptive backstepping controller is developed in Section 11.3, which ensures closed-loop signal boundedness and asymptotic output tracking despite the presence of the uncertain system parameters and actuator failure parameters. In Section 11.4, an extension to systems whose dynamics are state-dependent (beyond the class of output-feedback systems) is demonstrated by a second-order example based on either a reduced-order observer or a full-order observer. Such an observer-based adaptive actuator failure compensation design is illustrated in Section 11.4.4 by simulation results of an application to controlling the angle of attack of a nonlinear hypersonic aircraft model in the presence of elevator segment failures. The developed nonlinear output feedback designs can also be applied to linear systems, which may lead to improved system performance.
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