| Parallel mechanism have many advantages, such as high speed, high acceleration, high accuracy, high stiffness, good load-supporting, good dynamic performance, low power consumption. So more and more domestic and foreign researchers are attracted and widely concerned about it. High-speed, and light is the world's main symbol and trend of mechanical products. In the high-speed, heavy working conditions, the parallel mechanisms will produce elastic deformation, resulting to the kinematic and dynamic performance descended. Therefore, considering the flexibility and stiffness of PM(parallel mechanism), and evaluating the elastic deformation is very important when we do the analysis and design of parallel manipulator. Without 6-DOF(degree of freedom) parallel mechanism, less-DOF parallel mechanism of the branched-chain not only to provide the driving force, but also provide constrain toward the end. However, when doing the static analysis, the transmission character of constrain is ignored in existing researches.Based on analyzing the elastic mechanics and application of parallel mechanisms at home and abroad, inverse position, velocity, workspace of 3-SPR and 4SPS+SP PM is solved when considering the geometric constraints. Basing on the principle of virtual work, the statics of PM is analyzed and constraint force, active force is solved by exerting cosmos load to mechanism too. The static Jacobi matrix is derived and then the stiffness and the elastic deformation is analyzed. Using the software of 3D model, solid models are built. Then in the finite element environment, static finite element analysis is to be done, and the numerical results of elastic deformation are deduced. By contrasting the elastic deformation between numerical results and FEA result of solid models, the FEA result is verified correct. Therefore, analyzing the elastic deformation of solid simulate mechanism is practical by exerting constraint and load. Moreover, the dynamic analysis of 4SPS+SP PM is done. |
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