Robotic milling has a unique advantage for large and complex parts. However, it is extremely prone to low-frequency chatter due to the robot structure mode. In robotic milling, low-frequency chatter has a huge impact on machining quality and efficiency. In this paper, a novel MRF (Magnetorheological fluid) absorber is used to suppress low-frequency chatter during robotic milling based on the proposed low-frequency chatter suppression strategy. First, the GPR (Gaussian process regression) model is used to predict the impulse response function based on a few measured impulse response functions. Next, a cutting force model is developed considering the tool runout and the robot structure mode. The parameters and coefficients of the cutting force model are optimized by the measured cutting forces. Then, the low-frequency chatter frequency is predicted considering the modal coupling effect based on the predicted impulse response function and the simulated cutting force. Finally, an MRF absorber is designed based on the chatter frequency range. The controlled storage modulus of the MRF in the pre-yield region enables a wider frequency shift characteristic of the designed MRF absorber. The MRF absorber controls the input current based on the predicted low-frequency chatter frequency to achieve chatter suppression during robotic milling. Robotic milling experiments verified that the MRF absorber can effectively suppress low-frequency chatter. The experimental results show that the Energy Ratio Chatter Indicator of the industrial robot with MRF absorber is less than 0.1 under different milling conditions.

中文翻译：

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使用新型 MRF 吸收器抑制机器人铣削的低频颤振


机器人铣削对于大型复杂零件具有独特的优势。但由于机器人结构模式的原因，极易产生低频颤振。在机器人铣削中，低频颤振对加工质量和效率有巨大影响。本文基于所提出的低频颤振抑制策略，采用新型 MRF（磁流变流体）吸收器来抑制机器人铣削过程中的低频颤振。首先，GPR（高斯过程回归）模型用于根据一些测量的脉冲响应函数来预测脉冲响应函数。接下来，考虑刀具跳动和机器人结构模式，建立了切削力模型。通过测量切削力来优化切削力模型的参数和系数。然后，基于预测的脉冲响应函数和模拟的切削力，考虑模态耦合效应，预测低频颤振频率。最后，根据颤振频率范围设计了磁流变吸收器。预屈服区域中 MRF 的受控存储模量使所设计的 MRF 吸收器具有更宽的频移特性。磁流变吸收器根据预测的低频颤振频率控制输入电流，以实现机器人铣削过程中的颤振抑制。机器人铣削实验验证了磁流变吸波器能够有效抑制低频颤振。实验结果表明，带有磁流变吸收器的工业机器人在不同铣削条件下的能量比颤振指标均小于0.1。