Coordinated path following for unicycles: A nested invariant sets approach

We formulate a coordinated path following problem for NN unicycle mobile robots as an instance of a nested set stabilization problem. Stabilization of the first set corresponds to driving the unicycles to their assigned paths. Stabilization of the second set, a subset of the first, corresponds to meeting the coordination specification. The first set is stabilized, for initial conditions sufficiently close to the set, in a decentralized manner using feedback linearization. For general coordination tasks we utilize feedback linearization to stabilize the nested set in a centralized manner, again, for initial conditions sufficiently close to the second set. In the special case in which coordination entails making the unicycles maintain a formation along their paths, we employ a semi-distributed control law under less restrictive communication assumptions. Experimental results are provided.