Tham khảo tài liệu 'robot manipulators trends and development 2010 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 392 Robot Manipulators Trends and Development avoided by introducing a safety margin ranging from millimeter at the both ends of the semicircle geometry. The numbers of sampling measurement points depend on the method employed so the sampling points of every method do vary depend on the method employed. It is anticipated that the tracking error value will be quite high in certain slope region of contour gradient Prabuwono et al. 2009 . Fig. 12 shows the four degrees of freedom SCARA robot that used in this study. Fig. 12. The four degrees of freedom SCARA robot. Results The actual contour traced and the tracking error along contour matching the semicircle geometry of radius 40 millimeter is plotted. For adapting gradient method the enlargement of mean of tracking error with the value of - millimeter and the standard deviation of tracking error with the value of millimeter are shown in Fig. 13 and Fig. 14 respectively. The safety margin of to 1 millimeter is allowed at the beginning and near to the end of semicircle object in order to avoid measuring the very high slope at those regions. The adapting gradient measuring advance parameter of 1 millimeter is chosen for this contour following experiment. The total sample of good 79 points was collected over 80 millimeter horizontal measuring distance. Fig. 13. Contour traced along half circle geometry with adapting gradient method. Performance Evaluation of Autonomous Contour Following Algorithms for Industrial Robot 393 Fig. 14. Tracking error along half circle geometry with adapting gradient method. For staircase method the enlargement of mean of tracking error with the value of millimeter and the standard deviation of tracking error with the value of millimeter are shown in Fig. 15 and Fig. 16 respectively. The safety margin of to 1 millimeter is allowed at the beginning and near to the end of semicircle object in order to avoid measuring the very high slope at those .
