Constrained control with communication blackouts: Theory and experimental validation over Wi-Fi

Many modern applications have raised the issue of coordinating multiple agents under limitations given by the environment. In the industrial scenario, for instance, an interesting case-of-study consists of two mobile manipulators that cooperate to transport a load to a desired target position while avoiding obstacles. Wireless communications and physical constraints are the two key features of this kind of problems and the technological challenge is given by the merge of them: on one hand, constraints need to be always satisfied to guarantee safety, on the other, wireless networks are affected by random packet loss that usually allows only a probabilistic description of the system. Even more, if fast networks as Wi-Fi are adopted to achieve a low sampling period, the stochasticity of the communication is drastically increased and long communication blackouts are possible. For this reason, in this paper we focus on the case where the maximum number of consecutive packet losses is not bounded and we study a control scheme based on Reference Governor that guarantees to satisfy the constraints even in presence of communication blackouts. We provide the theoretical properties of the considered solution and we evaluate it through hardware-in-the-loop experiments based on actual realizations of a Wi-Fi channel obtained in laboratory.