Design of a robust path tracking controller for an unmanned bicycle with guaranteed stability of roll dynamics

Abstract

Controller design for a riderless bicycle is a difficult task due to its non-holonomic constraint and its complex dynamic. The problem will be more complex, when path tracking and stabilizing the roll angle of the bicycle are considered simultaneously. This paper proposes an analytical approach to stabilize the roll angle of an unmanned bicycle, in the meanwhile a desirable path is tracked by the bicycle. These two objectives are achieved due to the existing relation between the roll angle and the steering variable of the bicycle. In this paper, a multi-loop control structure is proposed to track a predetermined path. In the inner loop, the roll angle tracks a time-varying reference signal using the back-stepping method. This reference signal is manipulated in the outer loops to track the desired path. Moreover, the robustness of the system with respect to external disturbances is guaranteed by the Lyapunov redesign method. Finally, the efficiency of the proposed method is illustrated through computer simulations.

Keywords

• Unmanned bicycle
• nonlinear control
• back-stepping
• Lyapunov redesign method
• path tracking