Above and Below is a centralised multi-robot SLAM system for one uncrewed surface vessel (USV) and several AUVs, built on inter-robot loop closures against structures visible both above and below the waterline. Each robot runs its own state estimation; loop closures between each AUV and the USV data merge them into one graph that estimates every vehicle’s full trajectory. On real data from three environments AUV errors drop compared with single-robot SLAM, and the authors say it is the first USV-AUV multi-robot SLAM built on loop closures instead of acoustic ranging.
Relevance
Acoustic ranging needs vehicles close together, with a clear signal path and often synchronised clocks; loop closures on shared structure drop those needs. A direct case of cross-domain collaborative SLAM for multi-robot multimodal perception. It leaves open how a cross-domain loop closure is checked before it is trusted.