Design and Analysis of an Integrated SMC-TPWP Strategy for a Semi-active Air Suspension with Stepper Motor-driven GFASA by WEI CAIYANG M-B3-5520-1 Thesis Supervisor: Prof. Wong Pak Kin Thesis Co-supervisor: Dr. Xie Zhengchao Department of Electromechanical Engineering This research proposes an integrated sliding mode control (SMC)-two -point wheelbase preview (TPWP) strategy for semi-active air suspension (SAAS) system with gas-filled adjustable shock absorber (GFASA). First of all, a half-vehicle suspension model with rolling lobe air spring and GFASA is built, following with a road input model for the front wheel. By describing the detailed structure and working process of the GFASA, the regulating mechanism between the stepper motor and the designed GFASA is defined. Subsequently, the SMC algorithm is applied to generate the desired damping force with the real time state of the vehicle. Moreover, to predetermine the road profile for the rear wheel, a TPWP approach is proposed and its superiority is also illustrated as compared with the conventional single-point wheelbase preview (SPWP) approach. To evaluate the performance of the proposed system, numerical analysis is conducted with other three comparative schemes, namely passive suspension system, active suspension system with H infinity control, and SMC controlled SAAS system with adjustable shock absorber. Numerical results show that the integrated SMC-TPWP strategy can be successfully utilized in the SAAS system with stepper motor driven GFASA, and the vehicle performance with the proposed system can be greatly improved.