Real-Time Relative Positioning Study of an Underwater Bionic Manta Ray Vehicle Based on Improved YOLOx

Compared to traditional vehicles, the underwater bionic manta ray vehicle (UBMRV) is highly maneuverable, has strong concealment, and is an emerging research field in underwater vehicles. Based on the completion of the single-body research, it is crucial to research the swarm of UBMRVs for the implementation of complex tasks, such as large-scale underwater detection. The relative positioning capability of the UBMRV is the key to realizing a swarm, especially when underwater acoustic communications are delayed. To solve the real-time relative positioning problem between individuals in the UBMRV swarm, this study proposes a relative positioning method based on the combination of the improved object detection algorithm and binocular distance measurement. To increase the precision of underwater object detection in small samples, this paper improves the original YOLOx algorithm. It increases the network’s interest in the object area by adding an attention mechanism module to the network model, thereby improving its detection accuracy. Further, the output of the object detection result is used as the input of the binocular distance measurement module. We use the ORB algorithm to extract and match features in the object-bounding box and obtain the disparity of the features. The relative distance and bearing information of the target are output and shown on the image. We conducted pool experiments to verify the proposed algorithm on the UBMRV platform, proved the method’s feasibility, and analyzed the results.