Nonlinear Coordinated Path Following Control of Multiple Wheeled Robots with Bidirectional Communication Constraints

Abstract

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 coordination (in time) are essentially decoupled. Path following for each vehicle amounts to reducing a conveniently defined error variable to zero. Vehicle coordination 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.