Control of port-interconnected driftless systems

We use a recently reported extended Matrosov´s theorem to establish sufficient and necessary conditions to stabilize a chain of driftless systems. This benchmark can be regarded as a problem of controlling a communication channel and is a generalization of the well known chained-form non holonomic systems benchmark. Roughly speaking our extended Matrosov´s theorem is an extension of La Salle´s invariance principle to the case of non autonomous systems.