Navigation and positioning system design of an AUV underwater docking

AUV underwater docking is an effective way to provide energy supplement and complete information exchange with an AUV, which in turn allows an AUV make long-term missions in the water and avoid the need for repeated launching and retrieval. This paper proposes a new navigation and positioning system, which measures distance by underwater acoustic communication and by USBL. It can be used for underwater AUV remote positioning and guiding, so that an AUV can find the underwater feeder station in order to complete energy supply and exchange of information. The system consists of a T/R transducer at the end of the AUV; an electronic cabin within the chamber of the AUV, and, a T/R transducer USBL array and watertight electronic cabin at the end of underwater feeder station. For the hardware, the T/R transducers operating band is 10 kHz ~ 14kHz with overflow structure; there is a USBL array of conical structures; and, an electronic compartment which uses DSP, FPGA, MSP430 joint architecture. For the algorithms, the underwater acoustic communication equipment uses both LFM signal head and DSSS communication algorithms in order to obtain distance measurement results. The USBL array uses M sequence modulated signals emitted from the AUV terminal in order to measure direction. The system performance was tested in a lake, In the static case, the range accuracy was 0.2m ± 0.05%, and the orientation of the measurement accuracy is 0.3°. In the dynamic case, the positioning results were compared with GPS Real-time results, and their positioning track fitted well with each other.