Smart dampers-based vibration control – Part 2: Fractional-order sliding control for vehicle suspension system

Abstract

Semi-active suspension systems of vehicles using smart dampers (SmDs) such as magnetorheological dampers (MRDs) are actively developing as an attractive methodology to improve both ride comfort and road holding of many different vehicles including sedans. Because of the complex dynamic response of the SmDs and the whole system, an exact estimation of the time-varying control signal is difficult. Especially, the reality has shown that i) the error of the inverse SmDs (I-SmDs) due to noise in the measurement database used to build them may fade the control efficiency, and ii) for many high nonlinear systems, fractional-order derivative (FD)-based mathematical description could reflect their characteristics, attributes, and dynamic behaviors better than that using the integer-order-derivative-based traditional way. From the above aspects, we present an FD-based new control system for the half-car semi-active suspension system with MRDs. The proposed control system named FD-SMC consists of I-SmDs which are relied on measured data processed by the new filter CoFilter presented in Part 1 and FD-based sliding mode control (SMC) technique. The FD-SMC determines the control force, and subsequently, I-SmDs estimates current intensity applied to MRDs to generate the desired control forces. Surveys including a real application using an experimental apparatus are carried out to verify the control effectiveness of the proposed method as well as the possibility of development of this orientation.