Autonomous navigation based on iSAM and GPS filter for AUV

As we all known, autonomous navigation system is the basic of AUV movement, besides, accurate position estimation and reliable measurement are the keys of it. In order to avoid accumulating position errors in the long voyage by using navigation algorithm, we can depend on GPS. Due to the influence of diving and floating process, GPS data would slip. The slips affect the accuracy of navigation seriously and cause errors for AUV in path planning. Little slips can be accepted, while we can't tolerate large slips up to several hundred meters. This paper proposed the GPS filter algorithm, which combined with navigation algorithm such as DR, EKF and iSAM (incremental smoothing and mapping). In order to verify the validity and feasibility of the combination of navigation algorithm and the proposed algorithm, Sea trials were carried out on the high seas of the Yellow Sea. Experimental results and analysis show that the autonomous navigation approach combined GPS filter with navigation algorithm improves the accuracy of navigation compared with conventional method, at the same time iSAM has a higher accuracy than the other two algorithms.