Research Of SINS/DVL Integrated Navigation Technology

SINS/DVL integrated navigation system using the high accurate velocity offered by DVL to restrain the error accumulation of SINS is a widely-used under-water integrated navigation technology. However, there are still two main factors restricting the positioning accuracy of it. One is the misalignment between IMU and DVL. The other one is velocity error of DVL itself. For the two factors, researches on SINS/DVL integrated navigation technology have been done as the following aspects:1. The error model of SINS/DVL based on online estimation of misalignment angles and scale factor error is deduced. In the process of deducing,firstly, the error model of the SINS is deduced. Then, the error model of DVL based on misalignment angles and scale factor error is designed. Finally, the error model of SINS/DVL based on online estimation of misalignment angles and scale factor error is composed of the error model of SINS and the error model of DVL.2. The nonlinear global observability analysis approach is used to analyze the observability of SINS/DVL integrated navigation system. Though observability analysis, the estimatility of state variables in the integrated model is proved,and the rationalioty of the model is shown. The main conclusions are presented as following: the scale factor is observable when the carrier takes a movement with constant attitude and time-varying special force.And if the yaw-direction misalignment angle is only considered and the upward velocity is zero, the yaw-direction misalignment angle is observable when the carrier takes an linear movement with constant velocity. And the misalignment angles are observable when the carrier takes a movement with constant attitude and time-varying special force and linearly independent derivatives of special force for different time. The above conclusions are supported by simulations results.3. The error model of SINS/DVL is validated by vessel tests. The scale factor error is neglected in vessel tests because its influnce is very small when the vessel moves in normal speed. In the analysis of vessel tests, firstly,using calibration method, we attain the conclusion that the positioning accuracy is improved greatly after compensating by the integrated model based on misalignment angle and scale factor. Then, the navigation result of SINS/DVL based on online estimation of misalignment angle is analyzed, which shows that the online estimation method could effectively estimate the misalignment angle to slove the misalignment between IMU and DVL online, and improve the positioning accuracy of SINS/DVL, which could be usefull in the project.