H-infinity and Mixed H2/H-infinity with Pole-Placement Design via ILMI Method for Semi-active Suspension System

This paper aims to use H_∞ and mixed H₂/H_∞ techniques with a semi active suspension system to increase the passenger´s ride comfort performance. A two degree of freedom dynamic model of a vehicle semi-active suspension system was presented. The role of H_∞ is used to minimize the disturbance effect on the system output whereas H₂ is used to improve the transients against random disturbances. The capability of the system of improving comfort of operators has been evaluated through simulations carried out with a validated model of the entire vehicle. The results of this study revealed that the use of mixed H₂/H_∞ with pole placement for a semi-active suspension system showed a great improvement compared with H_∞ systems. In addition, the results of the simulation showed that ride comfortable of the vehicle can be improved effectively by using the semi-active suspension with mixed H₂/H_∞ control method, and also the mixed H₂/H_∞ control method more effective than the H_∞ control method. Finally, this paper showed a robust use of both H_∞ and mixed H₂/H_∞ problem which can be solved using linear matrix inequality (LMI) techniques.