Model Reference Adaptive Control and Adaptive Stability Augmentation

Abstract

Abstract A comparison of the standard concepts in MRAC design suggests that a combination of the implicit and the explicit design techniques may lead to an improvement of the overall system performance in the presence of unmodelled dynamics. Using the ideas of adaptive stability augmentation a combined stability augmented model reference design is proposed. By utilizing the closed-loop control error, a simple auxiliary controller is tuned, using a normalized M.I.T. rule for the parameter adjustment. The M.I.T. adjustment is protected against the effects of unmodelled dynamics by lowpass filtering of the gradient. The proposed method is verified through simulation results indicating that the method may lead to an improvement of the model reference controller in the presence of unmodelled dynamics.