取件机械臂定位精度的可靠性优化研究

针对取件机械臂存在的绝对定位精度低、成本高等问题,采用基于定位精度可靠度的评价方法对机械臂进行了可靠性优化设计。使用多体系统理论建立了机械臂的静态误差模型,基于蒙特卡罗法对其定位精度进行了分析,并得出了机械臂末端总的误差敏感度。采用响应面法建立了机械臂动态误差的近似模型,并得出了其输出量表达式,考虑工程实际中动态误差与静态误差的耦合,将动态误差等效为机械臂的末端形变,建立了动静态耦合误差模型。以定位精度可靠度为约束,成本与体积最小为目标,静态误差源与结构参数为设计变量,建立了定位精度的优化模型,利用NCGA-II算法结合蒙特卡罗法对设计变量进行了优化设计。研究结果表明,优化使定位精度可靠度满足实际要求,成本与体积分别降低了15%与7.6%,为机械臂的设计制造提供了依据。

Reliability optimization of location precision of extraction manipulator

Aiming at the problem of absolute location precision deficiency and high cost of the extraction manipulator, reliability optimization design about the manipulator was made based on the evaluating method for the reliability of the location precision. The static error model of the manipulator was set up with the application of multi-body system theory, location precision was analyzed based on the Monte-Carlo method and total error sensitivity of the end of the manipulator was calculated. An approximate dynamic error model of the manipulator was set up with the adoption of response surface method, and the output quantity expression was gained. Dynamic and static coupling error model was also set up through seeing the dynamic error as the deformation of the manipulator end, and with the consideration of coupling between the dynamic and static error in the practical project. Location precision optimization model was established with the location precision reliability as the constraints, minimum cost and volume as the goal, as well as the static error sources and structural parameters as the design variable;and the design variable was optimized with the NCGA-II combining with the Monte-Carlo method. The results indicate that actual requirement on the location precision is satisfied through the optimization;cost and volume are lowered by 15% and 7. 6% respectively, which all provide the basis for the design and manufacture of the manipulator.