Preliminary study on the inertial-Doppler localization of a deep-sea launcher hanging on a cable

This paper presents a localization method of a deep-sea launcher with a hybrid underwater navigation system. The under water navigation system mainly composed of an inertial measurement unit (IMU) and a Doppler velocity log (DVL). The implementation of DVL can improve the navigational performance of the IMU when an underwater vehicle works near sea bottom. A dynamic error model of a DVL-aided inertial navigation system is designed to implement an indirect feedback Kalman filter, and a measurement model is also designed. This paper demonstrates the enhanced performance of the DVL-aided hybrid navigation by conducting rotating arm test in ocean engineering basin at KRISO. The IMU and the DVL are embedded in a small fish attached at the rotating arm. Additional depth sensor and a magnetic compass are introduced in the measurement model. In addition, this paper also conducts a dead-reckoning navigation using the DVL and the magnetic compass. The dead-reckoning navigation system also shows better performance than the IMU-only navigation system.