Frequency-domain robust performance condition for plant and controller uncertainty in SISO LTI systems

This paper addresses the robust performance issue in the presence of controller uncertainty for single-input single-output LTI systems. All system uncertainties are modeled as additive, and the final result is a frequency-domain upper bound for controller uncertainty weighting function which acts as a sufficient condition for maintaining the systempsilas robust performance. The bound is calculated in a simple way which makes it suitable for real-time applications needing multiple controller design attempts due to changes in system components or environmental conditions.