Route optimizing and following for autonomous underwater vehicle ladder surveys

Abstract

An autonomous underwater vehicle is able to conduct coverage detections, such as sea terrain mapping and submerged objects detection, using sonar. This work addresses the task of both optimizing and following routes that present a ladder shape. First, a planning method to determine a nearly optimal coverage route is designed. The track spacing is optimized considering the seabed type and the sonar range for the purpose of increasing detection probability. It also adds adaptability to confined water, such as harbors, by decomposing the geometrically concave mission region during the processing of the environmental data. Next, a decoupled and two-layered structure is adopted to design the following controller. The route is followed in the form of sequenced-lines tracking. A proportion-integral-derivative algorithm with fuzzy parameters adjustment is employed to calculate a reference heading angle according to the transverse position deviation in designing the guidance controller. An adaptive nonlinear S-surface law is adopted to design the yaw control. The route following the method is demonstrated with sonar (including side scanning sonar and multi-beam echo sounder) imagery collected in terrain mapping and object detection through sea trials.

Path following control of an underactuated unmanned marine vehicle with model asymmetry in the presence of ocean current disturbances

“…28 Peng and Wang present a design method for output feedback path following control of underactuated UMV moving in a vertical plane without using surge, heave, and pitch velocities, and an extended state observer is developed to recover the unmeasured velocities as well as to estimate total uncertainty induced by internal model uncertainty and external disturbance 29 , while Jiang et al discuss the task of both optimizing and following routes that present a ladder shape; a planning method is proposed to determine a nearly optimal coverage route is designed, and then the track spacing is optimized considering the seabed type and the sonar range for the purpose of increasing detection probability. 30 The problem of three-dimensional (3D) path following control for an underactuated UMV in the presence of parameter uncertainties and external disturbances is addressed, 31 while a teach and repeat path following method is proposed by King et al 32 for an UMV navigating long distances in environments where external navigation aides are denied, and the method utilizes sonar images to construct a series of reference views along a path, stored as a topological map. Aiming to fuse bathymetric data from both systems for a full coverage survey with a confident map of these data, the selected model for the fusion process is derived from belief functions.…”