Robotic ball-end milling presents advantages such as a broad workspace, cost-effectiveness, and integration with vision/force sensing, making it a promising method in machinery manufacturing. However, its low stiffness leads to deformation error that seriously affects part profile accuracy. Reducing the deformation error is an effective method to improve the machining accuracy of robotic milling. However, existing research primarily focuses on translational deformation of the robot end effector calculated using average cutting force, overlooking the effect of changes in cutting force and deformation at the tool tip. To address these limitations, an optimization model is proposed to simultaneously optimize tool orientation and redundant angle to minimize force-induced tool tip deformation errors, accounting for cutting force variations at different tool postures. First, an error index for tool tip deformation is introduced, and it considers the comprehensive deformation of the tool tip point instead of the translational deformation of the robot end-effector to offer a more accurate analysis of the machining error. Second, a rapid calculation method for cutter-workpiece engagement is developed, facilitating efficient calculation of cutting forces and enhancing the accuracy of deformation error calculation under various tool orientations. Finally, employing a particle swarm optimization algorithm with multiple constraints, including robot kinematics and tool interference, both tool orientation and robotic redundant angles are optimized to minimize tool error index at each cutter location. Through a comparison test using a simplified aeroengine casing, the proposed method demonstrates effective enhancement of the accuracy of robot milling processing compared with unoptimized and existing studies.

中文翻译：

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通过同时优化刀具方向和机器人冗余，提高机器人球头铣床的加工精度


机器人球头铣床具有工作空间宽、成本效益高以及与视觉/力传感集成等优点，使其成为机械制造中一种很有前途的方法。然而，它的低刚度会导致变形误差，严重影响零件轮廓的精度。减少变形误差是提高机器人铣削加工精度的有效方法。然而，现有的研究主要集中在使用平均切削力计算的机器人末端执行器的平移变形上，而忽略了切削力变化和刀尖变形的影响。为了解决这些限制，提出了一种优化模型，以同时优化刀具方向和冗余角度，以最大限度地减少力引起的刀尖变形误差，同时考虑不同刀具姿态下的切削力变化。首先，介绍了刀尖变形的误差指标，该指标考虑了刀尖点的综合变形，而不是机器人末端执行器的平移变形，以提供更准确的加工误差分析。其次，开发了一种刀具-工件啮合的快速计算方法，有利于高效计算切削力，提高各种刀具方向下变形误差计算的准确性。最后，采用具有多个约束条件（包括机器人运动学和刀具干扰）的粒子群优化算法，优化刀具方向和机器人冗余角度，以最小化每个刀具位置的刀具误差指数。 通过使用简化的航空发动机外壳的比较测试，所提出的方法表明，与未优化和现有研究相比，所提出的方法有效地提高了机器人铣削加工的准确性。