Dynamic Path Generation Method for UUV Terrain Tracking Using Forward-Looking and Altimetry Sonar

Maintaining fixed altitude tracking navigation of seafloor terrain is a common form of motion, which is used by unmanned undersea vehicle(UUV) on marine survey and underwater target search missions, the core of this motion is how UUV can detect unknown undulating seafloor terrain in real time, and generate tracking paths online and dynamically based on detection information, so as to achieve fixed altitude tracking navigation on the terrain while avoiding collision with the terrain. In this paper, to solve the above problems, a method is proposed, which is of detecting terrain information based on forward looking sonar, and dynamically generating tracking path based on polynomial fitting. First, UUV uses forward looking sonar to conduct real-time detection of seafloor terrain. After affine processing of the obtained terrain detection data, fixed-height affine data with discrete characteristics can be obtained. Then, the cubic polynomial method based on least squares criterion is used to fit the affine data, and the navigation path of UUV terrain tracking based on polynomial function description is generated. Finally, a dynamic execution framework including sonar detection, data affine, path generation and tracking control is designed, in order to realize the real-time terrain tracking navigation mission of UUV. In this paper, through simulation of tracking on typical seafloor 'uphill' and 'mountainous' terrain, effectiveness and feasibility of the proposed tracking path generation and dynamic execution framework were demonstrated.