Submitted to the 38th IEEE Conference on Decision and Control, 1999.


Gap Metric Performance Bounds for Linear Feedback Systems

Michael Cantoni

Abstract
Upper and lower bounds on the difference in the performance of two linear, possibly infinite-dimensional and time-varying, stable feedback-systems that involve the same controller are derived in terms of the gap between the plants. To this end, the underlying geometry of the robust feedback stabilisation problem is exploited. The advantage of such an approach is that no specific system representation is required. With regard to extending the results to non-linear systems, a simple example is presented to show that the upper bound does not hold in general when the controller (in common) is non-linear.

Keywords : Linear Feedback Systems, Robust Performance, Gap Metric, Parallel Projections.