Theses and Dissertations at Montana State University (MSU)
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Item Evaluation of assembly routines with multitasking execution in a physical robotic cell(Montana State University - Bozeman, College of Engineering, 1989) San Martin, SergioThis research covered the development of multitasking execution programs and evaluation of twelve assembly sequences, in terms of efficiency and effectiveness, applied to a robotic cell under two software control methods. The assembly sequences were defined via analytical methods and verified later with a physical simu I at ion. The analytical methods used to define the sequences were the SPT rule, the LPT rule and the Branch and Bound algorithm. The software control methods were a single task execution program, and a multitask execution program. The single task execution programs performed all the activities in a sequencial mode. The multitask execution program allowed two activities to run simultaneously. The physical simulation was performed in a robotic cell containing two TeachMover robot arms, a central assembly area, and two bin cells built with Fischertechnik components. The part assembled was a representation of a circuit board with four microchips made of machinable wax. The control software was coded using ARMBASIC for the robot arms and TurboBASIC for the main program. The analytical results showed that using a single robot, the sequence with the best completion time was generated with the Branch and Bound algorithm. Also, this result was verified with the physical simulation that generated the best completion time using the Branch and Bound algorithm. Using two robot arms, the analytical results showed that the Branch and Bound algorithm under a multitask execution mode generated the best assembly sequence. In this case, the physical simulation showed different results. The best sequence found with the physical simulation was an adjusted sequence, running under a multitask execution mode, that removed the physical conflicts to avoid collisions in the assembly area. The physical interference could not be observed by the analytical methods. Therefore, the use of physical simulation to evaluate robotic motions is recommended.Item The design of an automatic vision switching system(Montana State University - Bozeman, College of Engineering, 1998) Feng, ChunshengThe importance of Robotics has been recognized by the manufacturing industry. The introduction of Computer Vision has greatly increased the versatility and application domain of robots such as the interaction between the robot and its changing environment. From previously developed vision position correction methods and currently used visual servo-feedback techniques, computer vision systems present many possibilities in improving the quality and productivity of an industrial product. But computer vision systems also have limits in dealing with some robotic tasks such as Storage Battery Cap Installation. Random geometric distortion exists, which results from the characteristics of battery material or from the positioning error of fixtures. Robotic teaching-playback method can not guarantee the assembly precision when deviation happens. A vision system introduced into the robotic system allows it to respond to an uncertain environment. Conventional vision correction methods only drive robots to the final position without considering robotic trajectory control. They reduce the robotic operation speed compared with stable conditions. Visual servo-feedback techniques can generate the optimal path and assembly precision, but the calculation of visual servo control algorithm is time consuming. It also reduces robotic execution time. In addition, random assembly tasks sometimes do not need vision correction. So the justification of this robotic vision system is improved robotic assembly accuracy that does not affect other robot performance. In this thesis a new robotic vision control system, Automatic Vision Switching System (AVSS), was designed. It was derived from the concept of Just-in-Time and dealt with the installation of storage battery caps. It demonstrated a vision system that functions to correct just when it is needed. Image processing techniques for solving the battery hole’s centroid values were included in AVSS design. The experiment was carried out based on an AdeptOne robot, a Vision-EZ system, a camera with eye-in-hand configuration, and a battery model. The experimental results showed that the AVSS can integrate a vision system with a robotic system efficiently. The AVSS identified the deviation of battery holes’ locations and generated the corrected values in real time. The control accuracy, operation speed and optimal path of robotic manipulator were obtained. The AVSS can also be used in other industrial tasks where random variation is present.