New research by Chinese scientists promises to make underwater navigation much more precise, accurate and fast.
The new research done by the Chinese Academy of Sciences addresses the issue that unmanned underwater vehicles typically navigate using a fusion of Strap-down Inertial Navigation Systems (SINS) and Ultra-Short Baseline (USBL) acoustic positioning, since GPS signals cannot travel through seawater.
In this case, navigation often begins with pre-measured sound speed profiles (SSPs). However, during long-duration operations, the SSP gradually drifts, leading to refraction effects that distort acoustic travel-time and angle measurements, ultimately degrading navigation performance.
Conventional correction methods, such as static conductivity-temperature-depth CTD casts or empirical models, are not able to keep pace with real-time environmental changes, highlighting the need for adaptive SSP estimation during deep-sea missions.
The team then developed a method for in-situ, real-time construction of SSPs. This reduces reliance on external CTD surveys and strengthens resilience against acoustic distortion. The new findings offer a promising foundation for next-generation autonomous underwater missions, which should benefit from greatly improved navigation.
According to the authors of the research:
“Traditional navigation often depends on static sound speed profiles, which quickly become outdated during long missions. Our model integrates physical ray-tracing with adaptive filtering, enabling ARVs to sense and correct sound-speed changes rather than rely on fixed inputs.”
You can find the original research here.
