Seabed following for small autonomous underwater vehicles

This paper presents a seabed following method for an under-actuated autonomous underwater vehicle navigating in unknown environment. Seabed following is achieved through construction of a local trajectory calculated thanks to bathymetric data given by basic sounders. Moreover, this trajectory respects the dynamic constraints of the vehicle. It is computed by using an algorithm based on simple geometric functions and interpolation curves called "semi-forced cubic splines." The bathymetric data comes from three electro-acoustic transducers situated in the front part of the vehicle. Our method has been validated with the hydrodynamic simulator of the "Taipan" vehicle, which is the autonomous underwater vehicle prototype of our laboratory. The front part of Taipan is fitted with measurement instruments. They have already been tested and results are presented