A Polar Initial Alignment Algorithm for Unmanned Underwater Vehicles.

Area of Science:

• Robotics and Autonomous Systems
• Navigation and Guidance Systems
• Ocean Engineering

Background:

• Strapdown inertial navigation systems (SINS) are vital for unmanned underwater vehicle (UUV) autonomy.
• Initial alignment is critical for accurate SINS performance, directly impacting subsequent navigation results.
• Conventional initial alignment algorithms face calculation overflow issues in polar regions due to rapid meridian convergence, rendering them unsuitable for polar UUV navigation.

Purpose of the Study:

• To develop a robust initial alignment algorithm for UUVs operating in polar regions.
• To address the limitations of conventional algorithms in polar environments.
• To ensure accurate and rapid initial alignment for polar UUV navigation.

Main Methods:

• A novel polar initial alignment algorithm comprising coarse and fine alignment stages was proposed.
• The coarse alignment utilizes the principle of conical slow gravity drift under a grid frame.
• The fine alignment employs a Kalman filter (KF) with velocity and attitude measurements under a grid frame.

Main Results:

• Simulations and experiments compared the proposed polar algorithm against conventional and transversal methods.
• The proposed algorithm demonstrated effective initial alignment for UUVs in polar regions.
• Results confirmed the algorithm's ability to achieve rapid and accurate initial alignment.

Conclusions:

• The developed polar initial alignment algorithm successfully overcomes the limitations of conventional methods in polar regions.
• The algorithm provides a reliable solution for accurate and efficient UUV navigation in extreme polar environments.
• This advancement is crucial for enhancing the operational capabilities of UUVs in polar exploration and research.