Research On Kinematic Characteristics And Dynamics Control Of Spatial Parallel Robot With Three Translational DOFs

Robot replacing the manual labor has become the catalyst of the development of the industry, and accelerated the arrival of turning point of each industry, with the rapidly rising labor costs and the adjustment of industrial structure. The world’s major economic entities are taking the development of robot as the national strategies. The ministry of industry and information of technology of our government has issued the guidance to the healthy development of the industrial robot, which clearly noted that with our country stepping from big manufacturing country to powerful manufacturing country, the demand for robots will be in great need.Compared with the serial robots, the parallel robot have the advantage in the aspects of compact structures, strong carrying capacity, high rigidity, no cumulative error, high precision, which give the people’s more and more favor. With the expansion of application areas of parallel robot, people found that in some certain areas, such as in electronics, food packaging, mechanical assembly, and other fields, parallel robots with full degree of freedom are not necessary but parallel robots with three translational are the best choice. At the same time, less degrees of freedom parallel robot also owning less motion pairs and poles number correspondingly, which will make the structure of parallel robots simpler and reduce the price of the manufacture and control of the robot. Especially parallel robots with the same branch chain and the symmetrical structure will have a broad application prospect.Supported by the National Science Foundation project (51275275) and Shandong Young Scientist Research Award Fund (BS2010ZZ006), the classification of structure synthesis, optimization and dynamics control of the parallel robots are studied.Firstly, conversely use of degree of freedom solution method based on the screw theory,13 kinds of different parallel robots with three translational degree of freedom and space symmetric configuration were got. Each kind of these parallel robots’motion pairs’ space layout is discussed in detail in each motion chain. The 3-CRP parallel robot was chosen as the configuration of parallel robot in this paper, based on punitive arrangement of motion pairs of each motion chain.Secondly, with the closed loop vector method, the kinematics model of 3-CRP parallel robot was established. By proposing the modified global kinematics index, the influence of the geometry size of the parallel robot on the workspace, dexterity and velocity characteristic index are analyzed thoroughly.Thirdly, with the orthogonal experiment method, the impact contributions amount of geometry parameters on the workspace, dexterity and velocity characteristic index of the parallel robot were analyzed in detail. Using the adaptive genetic algorithm optimization method, the optimization of the geometric parameters of the parallel robot was achieved under the requirements of the index of the workspace, dexterity and velocity characteristics.Fourthly, with the method of the virtual work principle, the dynamics model of parallel robot was established. In order to completely decouple the dynamic system, the torque controller based on the dynamic compensation was adopted. The controller’s validity was verified by the co-simulation of the MATLAB/Simulink and ADAMS. Considering the existence of dynamics modeling error of the parallel robot and the uncertainty of disturbance, robust controller was adopted, and its validity was verified by the co-simulation of the MATLAB/Simulink and ADAMS as well.