Non-linear co-ordinated path following control of multiple wheeled robots with bidirectional communication constraints

The paper presents a solution to the problem of steering a group of wheeled robots along given spatial paths, while holding a desired inter-vehicle formation pattern. This problem arises for example when multiple robots are required to search a given area in cooperation. The solution proposed addresses explicitly the dynamics of the cooperating robots and the constraints imposed by the topology of the inter-vehicle communications network. Lyapunov-based techniques and graph theory are brought together to yield a decentralized control structure where the information exchanged among the robots is kept at a minimum. With the set-up proposed, path following (in space) and inter-vehicle co-ordination (in time) are essentially decoupled. Path following for each vehicle amounts to reducing a conveniently defined error variable to zero. Vehicle co-ordination is achieved by adjusting the speed of each of the vehicles along its path according to information on the positions and speeds of a subset of the other vehicles, as determined by the communications topology adopted. Simulations illustrate the efficacy of the solution proposed. Copyright (c) 2006 John Wiley & Sons, Ltd.