Path tracking control of a laser light point by active visual servoing

Path tracking control of a laser light point (LLP) using an active camera is studied in this paper. The scope of the path could be out of the scene the camera in motion can capture at a time and no camera calibration is required. Two masking windows are defined, and only the images within the windows are processed in a control time step to achieve good speed of control response. Multilevel thresholding based on Otsu's discriminant analysis (1979) is applied to extract the LLP and path images. The curve-fitting technique is applied to skeletonize the path image whose continuity could be destroyed due to the LLP. As a skeletonized path is achieved within a masking window, the tracking direction will be built in consistence. A pixel of the skeletonized path is defined as a reference for regulating the LLP position. Included in the paper is also an experimental study to demonstrate how the path tracking control using an active camera can be realized in practice.