Modeling and feedback control of mobile robots equipped with several steering wheels

This paper deals with state feedback control of nonholonomic systems whose configuration space presents some singular points. The whole study is driven on the example of mobile robots equipped with several steering wheels. Linearizing dynamic feedback and time-varying feedback are successively considered to handle the tracking of a moving reference trajectory and the stabilization of the robots to a rest configuration, respectively. Both laws are designed in such a way that the systems singular configurations cannot definitely be met. Finally, a commutation procedure between the two laws is presented, in order to handle the very natural problem of tracking a reference trajectory ended by a rest configuration