| Industrial robots have been widely used in various industries. The SCARA robot of light structure and speed response is still playing an irreplaceable role in assembly, sorting, packaging and other fields. At present, there are a lot of mature SCARA robots, but the robot appearance, internal cable layout and work reliability of the domestic SCARA robot compared with the foreign products still exist a big gap. This paper intends to study the localization of SCARA robot and design a SCARA robot of compact structure, low cost and good performance.The SCARA robots at home and abroad have been carried out a thorough investigation. Advantages and disadvantages of various transmission schemes have been compared to determine the optimal transmission scheme which is suitable for this project, and the design parameter of the robot is determined. The design process of SCARA robot is stated by the mechanical system and control system design. The structural design mainly considers the ingenious components and cable layout, so that the robot has the beautiful appearance. Dynamics simulation is carried out by using the ADAMS and the selection of the motor and reducer are presented. The control system uses an open mode based on PC+ motion controller and uses the Visual C++ to write control software which is good for the function extension and upgrade of the robot.In view of the slight oscillation phenomenon at the end of the SCARA robot appeared in the debugging process, taking into account the rigidity which is an important factor to influence the positioning accuracy and dynamic performance, the stiffness of robot is related to the Jacobi matrix and the stiffness of the joint through the research of robot joint static stiffness model, and then the universal link length optimization of robots based on stiffness performance is put forward. Thus, with the calculation of typical transmissions of robotic joints, the minimal singular value of the stiffness matrix is first analyzed and taken as a criterion to evaluate stiffness performance. To measure the stiffness performance of a robot in its whole workspace, the global stiffness performance criterion is proposed and used as the objective to optimize link lengths of the robot. Finally, an application of the proposed optimization method is illustrated with the SCARA robot designed in the subject as an example. The feasibility and effectiveness of the method are verified by the application example. It is shown by the results that link length optimization is significant to the positioning accuracy and dynamic performance of a robot.In order to meet the need for fast and easy selection of the robot for enterprises and solve the problem that there is no uniform load check software of robots in the market, this paper uses Newton-Euler formula to deduce kinetic equations, gives the general load check selection algorithm and writes simple software of SCARA robot selection.Finally, in order to show the practical application of the SCARA robot, the SCARA robot is used in a small automated production line developed by our laboratory and the dynamic grasping experiment of SCARA robot guided by vision is carried out. The operation result shows the robot is of sorting speed, high precision and good overall performance, and can meet the requirements of the practical application which lays the foundation for the next step. |
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