Research on iterative closest contour point for underwater terrain-aided navigation

In order to provide underwater vehicle high-precision navigation information for long time, the coordinate properties of underwater terrain can be used to aid inertial navigation system (INS) by matching algorithm. Behzad and Behrooz (1999) introduce iterative closest contour point (ICCP) from image registration to underwater terrain matching and provide its exact form and prove its validity with an example. Bishop (2002) proves its validity systemically. However, their research considers that the matching origin is known exactly while it is seldom satisfied in practice. Simulation results show that ICCP is easy to diverge when the initial INS error is very large (such as 3km). To overcome the drawback, two enhancements are put forward. (1) The matching origin is added into matching process; (2) The whole matching process is divided into two phases: the coarse and the accurate. The coarse matching rules include mean absolute difference (MAD) and mean square difference (MSD) which is usually applied in terrain contour matching (TERCOM). The accurate matching is the ICCP optimization. Simulation results show that the updated ICCP matches application conditions very well and it is convergent with very high precision. Especially, when INS precision is not high, the updated ICCP matching process is more stable and its precision is higher than TERCOM's.