A SINS/DVL Integrated Navigation Algorithm Considering the Impact of Ocean Currents
Jianxiong Wei, Ya Zhang, Pan Jiang, Shiwei Fan, Fei Yu, Harbin Institute of Technology, China
Location: Galleria I/II
Date/Time: Wednesday, Apr. 22, 10:27 a.m.
With the development of science and technology, the exploration and development of ocean resources are increasing. Various ships and underwater vehicles will be widely used, and the accuracy and reliability requirements of navigation system are constantly improving. Strapdown inertial navigation system (SINS) / Doppler velocity log (DVL) integrated navigation system has become an important way of navigation for ships and underwater vehicles because of its advantages of concealment and autonomy, which is widely used in vehicles.
In the SINS/DVL integrated navigation system, DVL is an instrument which uses the ultrasonic transducer installed on the carrier to send ultrasonic waves to the seabed and measures the carrier velocity according to the principle of Doppler effect. DVL usually has two working modes: bottom tracking mode and water tracking mode. When the distance between the carrier and the seabed is within the effective range of DVL, DVL works in the bottom tracking mode, which can provide accurate and stable forward and lateral velocity of the carrier relative to the seabed. When the distance between the carrier and the seabed exceeds the effective range of DVL, DVL will automatically switch to the water tracking mode. At this time, the measured velocity is the velocity of the carrier relative to the water flow tracked by DVL, so it is also necessary to know the water flow velocity tracked, and the sum of DVL measurement velocity and current layer velocity is the velocity of the carrier relative to the seabed. If the current velocity is not considered when the DVL is switched from bottom tracking mode to water tracking mode, the positioning accuracy of SINS / DVL integrated navigation system will be seriously affected.
A SINS/DVL integrated navigation algorithm considering the influence of ocean current is proposed to meet the requirements of SINS / DVL integrated navigation system working in water tracking mode. In practical engineering applications, due to the change of the depth of sea water, DVL may frequently switch between the bottom tracking mode and water tracking mode. A design scheme of SINS/DVL integrated navigation system based on speed matching mode is proposed. When DVL works in the bottom tracking mode, it can output accurate velocity information of the carrier relative to the seabed, and it is unnecessary to consider the influence of current velocity. The velocity calculated by strapdown inertial navigation system in the navigation system is compared with the converted velocity measured by DVL as the observation measurement of Kalman filter. When DVL works in the water tracking mode, considering the existence of water flow velocity, different observation and measurement matrix are set up. The information of current velocity is introduced through observation, and the real-time estimation of current velocity is carried out by using Kalman filter, so as to effectively improve the integrated navigation and positioning accuracy of DVL for water tracking system.
The results of simulation and lake experiment show that the positioning error of SINS / DVL integrated navigation system increases obviously when DVL switches to water tracking mode without considering the influence of current. When the DVL works in the water tracking mode, the system still has a high positioning accuracy. It can be seen that the SINS / DVL integrated navigation algorithm proposed in this paper is effective and feasible.