| The navigation accuracy of AUV plays a decisive role to the success of the AUV underwater operations. SINS is a completely self-contained navigation system, with independent, covert, real-time, less susceptible to interference of the external environment, and outputting comprehensive parameters and many other unique comprehensive advantages, is usually used as a main navigation system of AUV. But it is difficult to work independently for a long while as the cumulative growth positioning error over time. The water surface or underwater vehicle can be accurately located in the local area with the acoustic positioning system with LBL.But the work is vulnerable to the effects of the Marine environment. Combined with the advantages and disadvantages of SINS and LBL acoustic positioning system respectively, a positioning method based on SINS/LBL interactive auxiliary and an integrated navigation system combined with DVL and MCP are proposed, to realize the demand for the AUV underwater navigation as high precision, long-endurance and long distance. Achievements are as follows:1. The status of research on AUV and AUV navigation technology have been fully investigated. And the basic working principle of LBL acoustic positioning system is introduced in detail. Then the underwater localization algorithm with TOA positioning method and under different number of array element suitable for the three-dimensional space are deduced, so as Chan algorithm and Taylor algorithm.2. According to the two positioning methods of TOA and TDOA, the corresponding navigation technology based on SINS/LBL interaction assisted are proposed. According to the positioning mode of TOA, an algorithm for calculating the equivalent sound velocity has been put forward based on the positioning results of the previous period, effectively reducing the ranging error caused by the uneven distribution of underwater sound velocity and sound ray bending and improving the positioning accuracy. Using the position information of SINS aided to choose the appropriate correlation peak for time delay estimation solves the fuzzy correlation peak problem on account of the multipath effect effectively, reducing the time delay estimation error and enhancing the TDOA location precision.3. Combined with the respective working characteristics of SINS, LBL acoustic positioning system, DVL and MCP, integrated navigation systems are designed respectively according to the centralized Kalman filtering technology and federal Kalman filtering technology, and the corresponding state model and observation model are established. Among them, the federated integrated navigation system is more suitable for underwater integrated navigation system, which has the characteristics of diversified information and high state dimension, and it has the advantages of less computation, better fault tolerance and higher flexibility.4. The model of underwater acoustic channel has been built according to the theory of underwater acoustic communication, and the transmission of underwater acoustic signal is simulated combined with the actual sample data of underwater environment from a Lake trial. Based on underwater acoustic signals simulated, the static positioning and dynamic operation with the schemes mentioned above are verified by simulation. The final simulation results show that the proposed scheme can effectively reduce the underwater acoustic positioning errors caused by uneven velocity of sound, the sound ray bending and multipath propagation, and improve the AUV underwater navigation and positioning accuracy. The whole navigation system can meet the demand of AUV underwater navigation and positioning. |
PDF Full Text Request