Guided Formation Control for Wheeled Mobile Robots

This paper considers the topic of formation control for wheeled mobile robots (WMRs). Specifically, the work deals with unicycle-type WMRs (i.e., underactuated vehicles that experience a lateral zero-speed constraint, such that their linear velocity at all times is aligned with the longitudinal axis of symmetry). Within a leader-follower framework, a so-called guided formation control scheme is developed by means of a modular design procedure which is inspired by concepts from integrator backstepping and cascade theory. Control, guidance, and synchronization laws ensure that each individual formation member is able to converge to and maintain its assigned formation position such that the overall formation is able to assemble and maintain itself while traversing a regularly parameterized path that is chosen by a formation control designer. The proposed version of the guided approach is completely decentralized in the sense that no variables need to be communicated between the formation members (hence, the formation suffers from graceful degradation). A key quality of the suggested scheme is helmsman-like transient motion behavior, which is illustrated through a computer simulation involving three unicycle-type WMRs