Sea Technology

MAY 2016

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

Issue link: http://sea-technology.epubxp.com/i/679071

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Navigation

Page 35 of 72

www.sea-technology.com May 2016 / st 35 A utonomous navigation is an im- portant task for USVs. Robot navi- gation methods involve solving the path-planning or obstacle avoidance problem and optimizing a path with respect to certain criteria. Obstacle avoidance comprises global and lo- cal obstacle avoidance. Many scholars have carried out extensive research on path planning with various algorithms. In local path planning, the APF method is a typical path-planning method for USVs. Although it is very suitable for low-level, real-time control of the robot due to its explicit physical parameters and simple mathematical description, there are some defects in the original algorithm. The accuracy of obstacle avoidance is affected by the measuring errors of lidar. This article focuses on solving problems of the defects of the APF al- gorithm and sensor errors. We divide USV navigation into two parts: ac- curate obstacle avoidance and fuzzy obstacle avoidance. First, the USV will avoid ob- stacles with the modifed APF algorithm in the ac- curate obstacle avoidance part. Second, the USV will be controlled by the fuzzy obstacle avoidance algorithm when the measuring errors of lidar are too big. Data Filter We use SICK's LMS511 lidar in the obstacle avoidance module. The resolution of the LMS511 aspect angle is 0.5°, and the scanning angular scope is from -5° to 185°. However, there exist er- rors in scanning data due to the effects of environ- ment and the USV's motion. Thus, it is necessary to flter original data to eliminate all unreliable data Autonomous USV Obstacle Avoidance Integrated Algorithm to Solve APF, Sensor Defects By Peng Wu • Dr. Shaorong Xie • Hengli Liu (Top) Simulation result in the general area. (Bottom) Simulation result in the local minimum area.

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