Control of Large Model Mismatch Systems Using Multiple Models

H-infinity control is an effective approach to handle model uncertainties. However, when modeling mismatch is large, it tends to be challenging to meet the desired requirements of both stability and performance by only using a single H(infinity)controller. This study presents a switching method to enhance the robust stability and performance of H-infinity control by dividing the range of dynamics into multiple uncertain models. The candidate robust controllers are designed by solving a set of linear matrix inequalities for each uncertain model. A structural scheduling logic that selects the most proper controller into, closed-loop is proposed. The selected controller can ensure bounded exponentially weighted H-infinity norm of the closed-loop switching systems. This work analyses their robust stability and disturbance attenuation performance via a linear fractional transformation by using the small gain theorem. The effectiveness of this method is validated with a fist-order inertial system with pure time delay.