Semi-active bicycle suspension fork using adaptive sliding mode control

In this paper, an adaptive sliding mode controller design for semi-active bicycle suspension forks with magnetorheological (MR) dampers is addressed. First, the mathematical equations of a quarter-vehicle suspension system for a bicycle fork are proposed. Next, the adaptive sliding mode control is utilized to design the robust controller with sprung and unsprung mass parameter estimations using the MR damper for eliminating external disturbances, such as wind gusts, load variations of bicycle body due to different riders, and rough terrain, etc. Accordingly, the Lyapunov stability theory is proposed to conduct the exponential stability analysis of the bicycle suspension system. By an equivalent control concept and limiting process, the approach trajectory is verified as being always continuous even when the suspension system is entered into the sliding surface vector under suffering from discontinuous switching conditions. Finally, the effectiveness of the adaptive sliding mode controller is demonstrated by computer simulations.