Stephen P. Linder

Robust Qualitative and Quantitative Methods for Disturbance Rejection and Fault Accommodation

December 16, 1997
3:30 PM
206 Egan

Abstract:

Disturbances caused by unmeasured inputs, plant perturbations or faulty actuators de-grade the robustness and performance of both control and diagnostic systems. When these distur-bances are unknown, robust accommodation of disturbances requires elabo-rate architectures. We, however, propose two new simple accommodation methodologies: one quantitative and the other qualitative. The quantitative methodology uses the integral ac-tion of the Proportional Integral (PI) Observer and Adaptive Observer to estimate and accommodate distur-bances. Our second meth-odology is based on qualitative models and uses stability and tracking behaviors, implemented with fuzzy rules, to achieve robust rejection of disturbances. Validation studies show that integral action is effective in estimating disturbances caused by unmeasured inputs, plant perturbations or faulty actuators, and a PI Observer-based controller will even outperform a Linear Quad-ratic Regulator in the presence of nonlinear actuator faults. The qualitative approach was validated with the 1992 ACC Robust Control Benchmark. Our fuzzy controller is the first published intelligent controller for the Benchmark, and achieves stability robustness and tracking robustness comparable to the best published compensators for the Bench-mark.

Thesis Committee:
Prof. B. Shafai (Advisor)
Prof. T. Cullinane
Prof. S. Kamarthi
Prof. G. Voland
Dr. Z. Korona