| This paper is combined closely with actual application of the car in body under flexible conveyor, assembly, positing system, proposed a flexible conveyor and positioning unit on the basis of parallel robot manipulator with three translational degrees of freedom. The kinematics analysis, performance evaluation and dimensional synthesis were carried out. Simultaneously, reliability and robust analysis were performed by considering the uncertain factors of motion process. The main contents include the following aspects:(1) According to the task characteristics of the conveyor and positioning mechanism, the conveyor and positioning mechanism and the overall design scheme of system were designed, and six degree of freedom flexible conveyor and positioning platform constronted four parallel manipulators with three degrees of freedom parallel manipulator 3-PUU was proposed.(2) The geometric characteristics of the parallel manipulator of 3-PUU configuration with three degrees of freedom were analyzed, and the kinematics inverse model of the parallel manipulator was established on the basis of closed vector and coordinate transformation theory. Velocity Jacobian matrix was deduced by adapting influence coefficient method based on the inverse kinematics.(3) According to the service application requirements of parallel manipulator, performance evaluation indices contained the workspace, kinematic dexterity, stiffness, bearing capacity and accuracy were established. Considering the geometric constraint and singular position of parallel manipulator, the workspace atlases were drew by using the boundary limit search method. On the basis of the workspace, the local performance indices and the global performance indices were established. On the basis of the comprehensive reflects the manipulator performance indices, the optimal work area was introduced in this paper, the optimal area of the dexterity, stiffness, bearing capacity, accuracy were established. Given all the kinematic performance indices mentioned in this paper, the optimal work area of the parallel manipulator was established.(4) In view of the performance indices of the parallel manipulator, the multi-objective optimization design mathematical model of the parallel manipulator was established. On the basis of the multi-objective gradient hybrid algorithm of Isight-PE, we search the Pareto in the design space; finally, we attained the optimizal Pareto of the parallel manipulator from the Pareto solutions. Considering the uncertain factors of the motion process, reliability and robust analysis were produced.(5) Virtual prototype design based on the Recur Dyn software. The three-dimensional model of flexible tooling system established in Solid Works was imported to the Recur Dyn simulation software, and constaints, kinematic joints, and contacts of the virtual prototype were added in the simulation model. Combined the engineering application requirements, we carried on the kinematic simulation analysis, finally drew the displacement, velocity and acceleration curves of driving legs, and meanwhile programed by using the MATLAB, got the spline curves, which verify the validity of the theoretical modeling.In this paper, the body in white flexible conveyor, assembly and positing system for automobile technical upgrading and innovation application based on a novel 3-PUU parallel manipulator has good innovation, good scientific significance and engineering practical value as well. |
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