NEW ROBUST STABILITY-CRITERION AND ROBUST CONTROLLER SYNTHESIS

In this paper, a new robust stability criterion for linear systems is proposed by combining the passivity and small gain theorems in differe nt frequency bands. A controller synthesis method based on the new cri terion is also developed, The controller can achieve both good perform ance and robustness in the same frequency band, if the uncertainty in that frequency band is passive or near passive. For processes with nea r passive lumped uncertainties with large gain in the frequency region in which good performance is required, the proposed controller can ha ve better performance than that of H-infinity control for the same rob ustness specification. (C) 1998 John Wiley & Sons, Ltd.