Aperiodic sampled-data control for semi-active suspension systems using a two-layer polytopic LPV model with H _∞ performance

This paper addresses the control problem for semi-active suspension systems using aperiodic sampled-data to enhance driving comfort against disturbances. A new two-layer polytopic Linear Parameter Varying (LPV) framework with state delay is used to model the system’s nonlinearity and handle uncertainties between the actual and measured system parameters. By applying a modified Krasovskii functional and Wirtinger’s inequality, a comprehensive stability analysis of the two-layer polytopic LPV system is carried out. An innovative relaxation technique, involving a slack variable matrix, is introduced to facilitate controller design. This approach yields new conditions for polytopic LPV controllers, formulated as Linear Matrix Inequalities (LMIs). For effective disturbance rejection, the H _∞ criteria is applied to the two-layer polytopic LPV model, excluding state delay effects from aperiodic sampling. This leads to the development of polytopic LPV controllers that ensure H _∞ performance. Simultaneously considering the derived design conditions for LPV controller design, the resulting closed-loop dynamic systems remain stable under sampling and meet the predefined H _∞ disturbance attenuation standards. Simulations on a quarter-vehicle model demonstrate that the proposed method, which accounts for sampling period effects in the design, significantly improves ride comfort and handling performance.