Research on a Novel 6-PRRS Parallel Robot System
|School||Harbin Institute of Technology|
|Course||Mechanical and Electronic Engineering|
|Keywords||Parallel robot Motion screw Jacobian matrix Dynamics Singularity|
Parallel robots process the merit of good carrying capacity, high movement precision, great rigidity and lower movement inertia, and it is applied more and more widely in every field of national product. 6-PRRS parallel robot is a special structure which possess many configurations, the mechanism, kinematics, dynamitic, error, control system and corresponding control method of a new 6-PRRS parallel robot are studied deeply based on the analysis on domestic and foreign the parallel robot theory, application and development. This type of parallel robot is applied mainly in NC working and medical attendance fields.6-PRRS parallel robot is one style of the parallel robots, and it has the character that it can be actuated by six line-motion mechanisms, and the driving mechanisms have more configuration styles. The discussed 6-PRRS parallel robot in this paper adopts the parallel driving mechanisms, which occur recently, but its feature is line-motion mechanisms are not is one plane and use screw actuation. Based on this configuration, the parallel robot has a large workspace and has the capacity of quick motion just for this reason too.The forward singularity, inverse singularity and combined singularity of the robot have been researched. In the analysis, spatial instant axis is presented, and the mechanism singularity of this parallel robot and other spatial mechanism has been explained based on spatial geometric. The correspondence of the matrix singularity and parallel robot singularity have been described and proved based on spatial instant axis and screw theory, and a special combined singularity of the 6-PRRS parallel robot is present. Using linear complex approximation algorithm, the solution procedure of the spatial instant axis has been corresponding analyzed. Combined motion screw and POE, the complete inverse kinematics of the 6-PRRS parallel robot is analyzed. The real-time inverse kinematics and Jacobian matrix have been research in the dissertation too.The workspace and motion features of this parallel robot are researched. The influence elements to the workspace are analyzed when the basic mechanism parameters are changing, and the sensitive influence element is found, at the same time, it is proved that the workspace of this parallel robot is infinity in theory based on its structure character. The operability and isotropic have been research too, and this two data is proved to be good, so this parallel robot can be proved to be fit for fast motion too.In dynamics, a simplified dynamics modeling method is presented which is fit for the spatial parallel mechanism in this dissertation, based on Lagrange method and virtual work principles the system dynamic of the robot is built, and the simulation sample is given which is the base of the dynamics control. In static, the stress comparison of the link is given when the guide rails distribute differently, and the simulation proves that the altitude variation of guide rails can bring corresponding magnification of the robot workspace, it can be prove that this type of mechanism processes better value in application.The static rigidity is researched by two methods. The rigidity and deformation are calculated by FEM software, and it can give reference to the mechanism design. The rigidity distribution in the workspace is analyzed by virtual work principles, and this can give reference to the optimum design.The CMAC+PD parallel control algorithm and sliding mode control method are adopted, and the simulation experiment of this robot is given. The control method overcomes some drawback of the common control methods, and improves the control effectiveness. Based on above theory analysis, a complete experiment system is build, and it includes the 6-PRRS parallel robot and corresponding control system. Based on the experiment system, the kinematics demonstration experiment ,trajectory testing experiment are completed, and these experiments verify the correct of the corresponding theory analysis, and it is useful for the further application of this parallel robot too.The work of this dissertation will provide foundation for parallel robot theory research and further application, it also provides theory knowledge for the theory study of other or new parallel robots, and it is useful for the originality innovation and development in the parallel robot field.