This paper proposes a multiple robot control algorithm to approach the problem of patrolling an open or closed line. The algorithm is fully decentralized, i.e., no communication occurs between robots or with a central station. Robots behave according only to their sensing and computing capabilities to ensure high scalability and robustness towards robots’ fault. The patrolling algorithm is designed in the framework of behavioral control and it is based on the concept of Action: an higher level of abstraction with respect to the behaviors. Each Action is obtained by combining more elementary behaviors in the Null-Space-Behavioral framework. A Finite-State-Automata is designed as supervisor in charge of selecting the appropriate action. The a...