Multi-vehicle Dynamic Pursuit Using Underwater Acoustics

Marine robots communicating wirelessly is an increasingly attractive means for observing and monitoring in the ocean, but acoustic communication remains a major impediment to real-time control. In this paper we address through experiments the capability of acoustics to sustain highly dynamic, multi-agent missions, in particular range-only pursuit in a challenging shallow-water environment. We present in detail results comparing the tracking performance of three different communication configurations, at operating speeds of 1.5m/s. First, when using full-sized modem packets with negligible quantization and a 23-second cycle time, the tracking bandwidth is 0.065rad/s. Second, a “lower bound” case with RF wireless communication, a 4-second cycle and no quantization has a tracking bandwidth of 0.5rad/s. Third, using 13-bit mini-packets, we employ logarithmic quantization to achieve a cycle time of 12 seconds and a tracking bandwidth of 0.13rad/s. These outcomes show definitively that aggressive dynamic control of multi-agent systems underwater is tractable today.