交叉杆并联机床结构参数优化

Structural Parameter Optimization of a Crossbar Parallel Machine Tool

增大工作空间和提高灵巧度是并联机床设计的一项重要任务。依据运动学反解,采用三维搜索的方法得到了带约束条件的交叉杆并联机床的工作空间;利用自然坐标法推导了该机床的新型雅可比矩阵;基于工作空间和新型雅可比矩阵获得了交叉杆并联机床的灵巧度分布。在此基础上分析了机床各结构参数对工作空间和全域灵巧度指数的影响规律,然后用最小二乘法进行曲线拟合并以工作空间指数和全域灵巧度指数为优化目标对该机床进行优化,与优化前相比,两项指标分别增大了0.40倍和0.26倍,达到了机构优化的目的。

Increasing workspace and improving dexterity are important taskes for the design of par- allel machine tool. On the basis of inverse kinematics, workspace of the crossbar parallel machine tool with constraints was obtained via three-dimensional search method. New Jacobian matrix of the ma- chine was also deduced by using the natural coordinate method. Dexterity distribution of the machine was acquired as well based on the workspace and new Jacobian matrix. Then, the impacts of structur- al parameters on workspace and global dexterity index were analyzed, then least square method was applied to curve fitting and the optimization of these structural parameters were carried out by intro- ducing workspace value index and global dexterity index as the global optimization goals. Compared with the original data, each of them increases by 0.40 and 0.26 times respectively, achieving the aim of mechanism optimization.