Abstract
This paper considers the problem of controlling both the planar position and the direction of underactuated two-wheeled mobile robots with a reduced number of actuators for the case where some physical parameters are unknown but the upper bounds are known. The robot is a nonholonomic system described by a set of nonlinear equations. A new adaptive control system based on an on-line identification of the physical parameters is presented. A smooth and time-varying coordinate transformation is utilized to reduce the stabilization problem of the nonholonomic system to a well-known pole-placement problem of a linear time-invariant system. As a result, the proposed control system not only assures global exponential stabilization but also can specify the convergent rates of all the states. Moreover, the design method is simple and straightforward. Some simulations are performed to validate the effectiveness of the proposed controller.
