Underwater autonomous orientation using submarine light intensity gradient

It is a huge challenge for autonomous underwater vehicles (AUVs) to determine heading autonomously without the signal of satellite or underwater acoustic positioning system. The underwater polarization navigation is a newly-developed solution for self-orientation. However, the polarization navigation depending on the Rayleigh scattering model is susceptible to the multiple scattering induced by water depth. To address this issue, the underwater light intensity field is exploited benefiting from its environment suitability. By means of calculating the gradient of light intensity, a vector-field model, with resemblance to the ideal Rayleigh model in geometry, can be established for solar-tracking. The integrated navigation model is built based on the solar vector estimated by light intensity gradient (LIG) and inertial navigation system for heading determination. The static test in water tank and dynamic sea trial were conducted to validate the effectiveness of the LIG-based solar-tracking and orientation method, respectively.