Development of a laser-based vision system for an underwater vehicle

The paper describes two crucial modules of a laser-based vision system for an underwater welding vehicle which is a joint research project of Nanyang Technological University (Singapore) and a major international corporation. The vehicle would automatically approach an underwater object, find weld seams, detect cracks and finally weld them. The first module is the ranging system. The experiments have shown that much better accuracy has been achieved when approximating polynomial functions are used instead of standard triangulation techniques. The second module detects and localises weld seams by extracting shape primitives corresponding to the expected configuration of seams from the laser-produced contours. Although the experiments are currently conducted in air, the proposed solution should be equally suitable for an underwater environment as well