Design and Experiment of Hierarchical Coordinated Control for Trajectory Tracking of Unmanned Motorcycles

The non-coaxial two-wheeled unmanned plat-forms, such as unmanned motorcycles and unmanned bicycles, have garnered significant interest from both academic and industrial communities because of compact structure and high maneuverability in narrow and uneven terrain environment. However, such unmanned platforms are essentially underactu-ated system with a strong coupling between the steering, drive and rolling subsystems, contributing to significant challenges in balancing and trajectory tracking control. To address such issues, this paper proposes a hierarchical coordinated trajectory tracking control scheme for unmanned motorcycles operating in complex environment with unmodeled dynamics and external disturbances. Specifically, an upper-level motion planner is designed to account for velocity constraints by using a nonlinear saturation function. Meanwhile, a lower-level dynamic tracking controller based on the linear quadratic regulation (LQR) method is constructed to track the planned velocity signal due to its simple control structure and parametric adaptability characteristic. By integrating kinematics and dynamics control in this hierarchical approach, the design complexity of the control system is considerably reduced, and the robustness of the system is further enhanced. Finally, numerical simulation and experimental test are performed to validate the feasibility and effectiveness of the proposed hierarchical coordinated trajectory tracking control scheme.