In the design of robotic arms, structural topology optimization considering variable configurations with high computational efficiency is still a challenging issue. In this paper, the worst case identification based topology optimization of a 2-DoF hybrid robotic arm is accomplished, and the presented work mainly covers: (1) efficient worst case identification; (2) optimization problem construction and (3) iterative criterion and filtering method with fast convergence. The forward kinematics are investigated to identify the workspace. Thereafter, the equivalent external load is proposed to unify the effect of axial load and shear by force analysis and compliance calculation. The worst case is the load case with maximum compliance and can be located efficiently by searching for the maximum equivalent external load. The optimization problem is constructed based on the solid isotropic material with penalization (SIMP) interpolation scheme. For links with multiple worst cases, the objective function is constructed as the weighted sum of compliance under each worst case. For better computational efficiency, the modified guide-weight method is used to solve the optimization problem. To eliminate the mesh dependence and checkerboard problem, a guide weight filtering method is proposed. Under the guidance of derived optimal topology, the CAD model of the hybrid robotic arm is presented. The effect of the optimization is testified through performance comparison in finite element analysis. The optimization method can derive the optimal topology with global validity within allowable computational time and the optimization approach can be applied to other hybrid robotic arms as well.

中文翻译：

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基于最坏情况识别的2-DoF混合机械臂拓扑优化

在机械臂的设计中，考虑具有高计算效率的可变配置的结构拓扑优化仍然是一个具有挑战性的问题。本文完成了基于2-DoF混合机械臂的最坏情况识别的拓扑优化，主要工作包括：（1）有效的最坏情况识别；（2）优化问题的构造和（3）具有快速收敛性的迭代准则和过滤方法。研究正向运动学以识别工作空间。此后，通过力分析和柔度计算，提出了等效的外部载荷以统一轴向载荷和剪切力的影响。最坏的情况是具有最大顺应性的负载情况，可以通过搜索最大等效外部负载来有效地定位。基于带罚分的固体各向同性材料（SIMP）插值方案构造了优化问题。对于具有多个最坏情况的链接，目标函数构造为每个最坏情况下的合规性加权总和。为了获得更好的计算效率，改进的指导权重方法用于解决优化问题。为了消除网格的依赖性和棋盘格问题，提出了一种指导权重过滤的方法。在推导的最优拓扑结构指导下，提出了混合机械臂的CAD模型。通过有限元分析中的性能比较证明了优化的效果。