A smooth path tracking algorithm for wheeled mobile robots with dynamic constraints

In order to avoid wheel slippage or mechanical damage during the mobile robot navigation, it is necessary to smoothly change driving velocity or direction of the mobile robot. This means that dynamic constraints of the mobile robot should be considered in the design of path tracking algorithm. In the study, a path tracking problem is formulated as following a virtual target vehicle which is assumed to move exactly along the path with specified velocity. The driving velocity control law is designed basing on bang-bang control considering the acceleration bounds of driving wheels. The steering control law is designed by combining the bang-bang control with an intermediate path called the landing curve which guides the robot to smoothly land on the virtual target's tangential line. The curvature and convergence analyses provide sufficient stability conditions for the proposed path tracking controller. A series of path tracking simulations and experiments conducted for a two-wheel driven mobile robot show the validity of the proposed algorithm.