Dynamic Motion Planning and Adaptive Tracking Control for a Class of Two-Wheeled Autonomous Vehicle With an Underactuated Pendular Suspension

This paper investigates a dynamic motion planning approach and an adaptive tracking control scheme for a class of two-wheeled autonomous vehicle with an underactuated pendular suspension subject to nonholonomic constraint. Compared with the wheeled inverted pendulum system, this kind of two-wheeled pendular suspension (WPS) vehicle is more suitable for autonomous exploration in the complex unstructured environment. By Lagrange principle, a four-independent-coordinate dynamic model, which can describe the multivariate, nonlinear, and underactuated characteristics of the system, is first proposed. Besides, a reduced order dynamic is developed in the following so as to tackle the nonholonomic problem, and then the three-independent-coordinate reduced order dynamic is divided into an actuated part constituted by the rotational subsystem, and an underactuated part combined by the longitudinal and the swing angle subsystems. The sliding mode control (SMC) technique is utilized to construct the controller; especially, a composite sliding mode surface is proposed which can realize the velocity tracking and oscillation suppression for pendular suspension simultaneously. Furthermore, the adaptive mechanism is employed to update the true values of the inaccessible physical parameters which can enhance the adaptability of the WPS vehicle in unstructured environment. In addition, a dynamic motion planning method is presented, by aid of which the vehicle can track an arbitrary trajectory in Cartesian coordinate. The simulation results show the effectiveness and merits of the proposed control approaches.