Adaptive and Reconfigurable Flight Control

An indirect adaptive and reconfigurable flight control system is developed. The three-module controller consists of 1) a system identification module, 2) a parameter estimate smoother, and 3) a proportional and integral compensator for tracking control. Specifically: 1) The identification of a linear discrete-time control system's open-loop gain is addressed. The classical Kalman filter theory for linear control systems is extended and the control system's state and loop gain are jointly estimated on-line. Explicit formulae for the loop gain's estimate and estimation error covariance are derived. The estimate is unbiased and the predicted covariance is reliable. 2) An adaptive smoother is developed to reduce the fluctuations automatically in the gain estimate, and bursting, caused by instances of poor excitation. 3) Special attention is given to the design of a proportional and integral tracking controller. The outputs of the system identification and gain smoother modules are used to adjust the tracking controller's gain continuously in order to compensate for a possible reduction in the loop gain due to control surface area loss, thus achieving the benefits of adaptive and reconfigurable control. The performance of the adaptive and reconfigurable controller in the face of a simulated control surface failure is examined in carefully designed experiments. The adaptive controller developed in this dissertation and illustrated in a flight control context is applicable to a wide range of control problems.

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