Performance Evaluation of Autonomous Contour Following Algorithms for Industrial Robot

The current trend towards industrial robotics requires the development of simple programming techniques. Programming by demonstration has emerged as one of the most promising solutions for effective programming of robot tasks (Ikeuchi & Suehiro, 1994; Zollner et al., 2002). Contour following is one of basic task in industrial robot manipulation. In this task, the robot is holding a tool to follow the contour of an object whose shape and pose are often unknown (Mi & Jia, 2004). These applications include part polishing, inspection, sealing, painting, cleaning, modeling, etc. During the following process, the tool is constrained on the surface to maintain contact force while moving along some tangential direction. In order to use robotics for such application two sequences of step need to be considered, the programming phase and the playback phase. In the programming phase, teaching a group of points is required while for playback phase, the robot Tool Centre Point (TCP) will follow the taught points recorded previously. This programming phase especially for contour following application is quite tedious and time consuming. For example, in order to track an arc, the robot programmer needs to manually use teaching box or teaching pendant to jog (powered motion) the robot Tool Centre Point to three points that enclosed an arc. For a complex contour, several series of three points must be taught, besides finding the optimum process parameter (voltage, current and electrode speed for arc welding application) related to those points. Next, the motion instruction, speed and type of termination that describes the closeness of zoning radial distance to the taught points needs also to be defined. The programmer must iterate the points and process parameters several times until the optimum combination are achieved. In comparison to assembly operation where the programmer just need to teach few points such as approach, insert and depart points, contour following for painting, arc welding and sealing application requires a large number of points recorded and at the best location. After all the best program and process 17