A visual servoing system for edge trimming of fabric embroideries by laser

摘要

This paper describes a position-based visual servoing system for edge trimming of fabric embroideries by laser. The high-speed vision system based on a 220 Hz digital camera and the TMS320C40 parallel DSP processor is presented, and the novel image processing algorithm developed for seam tracking applications is briefly explained. Two methods for seam trajectory generation are discussed. In the first method the tracking trajectory is determined only by using the vision data, in the second method, which is suitable for periodic patterns, the predetermined path data is modified by the vision data. A tracking controller using a feedforward controller in the tangential direction of the seam and a feedback controller in the normal direction is described. The custom built manipulator is a four-axis velocity controlled gantry robot with independent PID controllers for each axis. The axes' reference speeds are commanded and updated by the top-level tracking controller in equal time intervals. The gantry controller program runs on a Pentium PC. The experimental results in edge trimming of different seam patterns are presented.