Integral Constraints Due to Stable Pole-Zero Near Cancellation in Scalar Feedback Systems

This paper developed time domain integral constraints on error response for SISO feedback control systems due to nominal plant's near cancellation of stable pole-zero near the -axis. This integral constraints are satisfied by any feedback control systems. These integral constraints gave new insight into the inherent trade-offs. It will result in the the settling time longer or error response's infinite norm larger when there are near cancellation of stable pole-zero + near the -axis. Hence, when designing feedback control systems, it is necessary to avoid the compensator's poles and zeros nearly cancelling the nominal's zeros and poles (even if these poles and zeros are stable)