Underwater Target Tracking Based on Acoustic-Optical Fusion for Multi-AUV Systems

Multi-source fusion technologies have emerged as a critical approach for underwater target tracking, where acoustic-optical fusion demonstrates significant potential for tracking highly-maneuvering targets in small-scale scenarios, particularly in terms of continuity and stability. Different from existing studies that focus on image fusion, this work addresses the limitations of acoustic measurements, such as low update frequency and time delays. By leveraging high-frequency optical observations, an acoustic-optical fusion mechanism has been proposed for multi-autonomous underwater vehicle (multi-AUV) systems, which alleviates the time-lagged effect of traditional single-acoustic tracking for highly-maneuvering targets and, accordingly, improves the tracking accuracy. Specifically, an acoustic-optical fusion target tracking framework is designed based on the different characteristics of optical and acoustic measurements, which consists of the following two parts. In the “high-frequency optical estimation”, the inter-frame changes of the target on the image plane are used to mitigate the impact of acoustic measurement delays. For the multiplicative noise from the optical observation, bias compensation strategies have been designed to reduce the estimation error. As for the “acoustic-optical fusion”, this article integrates measurements from multiple AUVs to obtain higher tracking accuracy. The collaborative effort of multiple AUVs overcomes individual measurement limitations and ensures more reliable tracking in dynamic underwater environments. Extensive simulations and experiments are conducted to validate the proposed algorithms in terms of tracking accuracy and real-time performance.