Control of nonholonomic systems via dynamic compensation

The problem of controlling nonholonomic systems via dynamic state feedback and its structural aspects are analyzed. Advantages and drawbacks with respect to the use of static state feedback laws are discussed. In particular, nonholonomic constraints are shown to yield possible singularities in the dynamic extension process. Nevertheless, these singularities can be avoided by the proper design of a discontinuous external control law achieving stabilization of the transformed linear system. This is illustrated through simulations for a unicycle.