Advanced navigation method of autonomous underwater vehicle using artificial underwater landmark and deadreckoning

摘要

Recently, investigation of underwater structure and fresh water environment such as lake and dam which are closely related with human life have got much attention. Even though Autonomous Underwater Vehicles (AUVs) are anticipated to be very useful tools for mentioned missions, problems of conventional navigation method prevent AUVs from accomplishing them. In this paper, a new underwater navigation method for AUVs is proposed based on Artificial Underwater Landmarks (AULs) which are recognized by a vision system implemented in the robot. When an AUV cruises by deadreckoning, position error accumulated gradually depending on characteristics and direction of navigation devices reliability. When the error is within an acceptable range for finding a specific AUL along the track line, the AUV can correct the position and direction by referring to those of the AUL. Then, the AUV continues to cruise by deadreckoning again. Since the underwater vision system is requested to have high reliability, a new underwater image processing strategy is introduced based on analysis of underwater vision environment. Configuration of the AUL, shape and color of targets on it are designed to optimize image processing and recognition. Experiments were carried out to demonstrate the efficiency of the proposed navigation method by the intelligent AUV "Tri-Dog1".