Distributed Sensing and Data Collection via Broken Ad Hoc Wireless Connected Networks of Mobile Robots

This paper reports on ongoing work to develop ad hoc wireless networking for application in distributed mobile robotics. The paper discusses a mission scenario in which a number of mobile robots are required to autonomously disperse into a physically bounded region, take sensor readings at predetermined time intervals, and then communicate the sense data back to a single collection point. There is assumed to be no overall command and control structure. The robots are assumed to be equipped with low-power short-range wireless network interfaces, which only allow direct communication with near neighbours, and overall an ad hoc (multi-hop) wireless networking scheme is employed. Furthermore, it is assumed that there are insufficient robots to allow full wireless connectivity through the region so that, at any instant, the robots actually appear as a set of disconnected sub-nets (i.e. a broken ad hoc network). The paper proposes a mechanism that exploits the mobility of the robots to overcome the lack of overall wireless network connectivity, resulting in a sub-optimal but robust scheme for garnering sense data. The paper presents simulation results that show how the arithmetic mean data collection delay varies with the number of robots deployed. The paper concludes that in mission scenarios that do not require data collection in real-time and where occasional data loss (erasure) is acceptable, then the proposed data collection mechanism is feasible, robust and economical in terms of the number of robots required.