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

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