The Optimization Design Of Lower-mobility Paralle Robot For Vibration Reduction

With the continuous development of modern industry, the requirements for efficiency and safety on production line are getting higher and higher, but the traditional production line in our country still using large number of people to finish the repetitive work and assembly works, it is not only exist people management problem, but also exist the problem that it’s hard to ensure the quality of productions. For these reasons, the demand for robot in the market is increasing rapidly. The structure of robot can be divided in two kinds, serial robot and parallel robot, and in parallel robot, the low-mobility robot works more efficiently than serial robot, for this case, the low-mobility robot get more and more attention from the con enterprises and research institutions in these years.Beside the innovations of robot’s configuration, it also improved robot’s performance by study the problems occurred in the practical application of robots. So this paper based on the problems in practical applications, using Delta robot as study object, studied the problems that how to reduce the vibration of low-mobility parallel robot. The mainly job of this paper can be described as following:First, this paper analyzed the possible reasons that cause vibration in robot, and divided the reasons into two parts:hardware and software. On the hardware part, the reason can be further divided into another two parts:the problem in theoretical model and problem in the robot structure.And then, this paper analyzed the optimization method to reduce vibration based on the theoretical model of Delta robot. By analyzed the optimization method of robot, we found that the status of vibration can be described by the stiffness of robot. By analyzed the kinematic model of robot, we get the way to described the stiffness, then simplify the description according to the actual situation of Delta robot. After that, we found that the robot’s stiffness is different at different point in robot’s workspace, so the goal of the optimization is to maximize the minimum stiffness value. As the length of robot’s linkages are the parameters which can affect the stiffness value of Delta robot, after analyzed, we chose two linkage length of robot as the variables, because of the uncertainty of the stiffness distribution, we finally chose the control random search method to found the optimal linkage lengths of robot as it is easy to programming.Finally, by using the new values of linkage length, and aiming at the problems we meet in the last version of Delta robot we made, we made several optimizations on the structure of robot, including the structure of active rod, the arrangement of driven rods, the structure rotation axis, and the structure to fix the robot. After manufacture and assembly works, we build the model Delta robot, then we get the trajectory that robot running by using laser tracker, and made a contrast between the data of old Delta robot and new delta robot, at last we found that the robot after optimization performed better than the old one in vibration suppressing.