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Tham khảo tài liệu 'crc press - mechanical engineering handbook - robotics 1 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 14-100 Section 14 The robot may require an assortment of different tools and a tool changer to reach all edges. If these measures do not allow access then multiple setups may be needed to present all features for finishing. Most robotic surface finish machining applications use compliant abrasive processes. Force control is required in some applications to keep tool pressure constant. Force controllers are most often incorporated in the end effector or in the tool stand. Figure 14.11.5 shows a robot equipped with a force-controlled finishing end effector using a servo-controlled pneumatic actuator that is capable of applying consistent tool pressure. Through-the-arm robot force-control is available from some robot manufacturers but its usefulness is limited to applications requiring slow feed rates because of slow mechanical response. FIGURE 14.11.5 Robot equipped with force-controlled end effector grinds tool marks from ship propellor. Courtesy of The Automation and Robotics Research Institute The University of Texas at Arlington. Path planning and programming of edge and surface finishing for complex-shaped parts can be very difficult and time consuming. Both tool position and tool pose are critical in obtaining the correct tool contact area. Tedious paths programmed using the teach method require hundreds of hours to develop because of the large number of taught points. Generating the path control sequence is a major problem in manufacturing operations which produce a variety of complex-shaped parts. An example is in polishing large asymmetric-shaped aircraft skin panels. A more difficult automation problem is robotic spot finishing of flaws and other anomalous regions of the part surface when their location and extent are not known before set-up time. The reason is that the paths must be planned generated and executed on-line. This type of motion generation system requires part modeling and computational functions not available on most robot controllers. Figure
