In the stability analysis of robotic milling processes, two primary chatter mechanisms have been identified — regenerative chatter and mode-coupling chatter. They are known to result in undesirable outcomes such as poor surface finish, dimensional errors, and reduced lifespan of tools and machines. Recently, there is increasing disagreement regarding the existence of mode-coupling chatter. Specifically, Mode-coupling chatter has been suspected from the perspective of Stability Lobe Diagrams (SLDs) because of the mismatch between experiments with the predicted SLDs obtained by the mode-coupling mechanism, especially the mismatch between the two in terms of spindle speed dependency on stability boundary. Nonetheless, the opinion has not been fully recognized in robotic milling. Therefore, to investigate the existence of mode-coupling chatter further from the perspective of signal processing, this paper proposes a novel method for determining chatter mechanisms based on two chatter type indicators (CTIs) comprised of the number of true modes (NTM) and the distribution of characteristic multipliers (DCM). Through the simulation using Mathieu equation, the NTM and DCM are obtained by dynamic mode decomposition (DMD) and proved to be effective in distinguishing the response signals of mode-coupling chatter from regenerative chatter. Through robotic milling experiments and Spearman correlation analysis, the mode-coupling chatter is deduced not to happen in robotic milling.

中文翻译：

---

基于动态模态分解提取的颤振类型指标研究机器人铣削中模态耦合颤振的存在性


在机器人铣削过程的稳定性分析中，已经确定了两种主要的颤振机制——再生颤振和模式耦合颤振。众所周知，它们会导致不良后果，例如表面光洁度差、尺寸误差以及工具和机器寿命缩短。最近，关于模式耦合颤振是否存在的分歧越来越大。具体来说，从稳定性波瓣图（SLD）的角度来看，模式耦合颤振被怀疑是因为实验与通过模式耦合机制获得的预测 SLD 之间不匹配，特别是两者之间的主轴速度依赖关系不匹配。稳定边界。尽管如此，这一观点在机器人铣削领域尚未得到充分认可。因此，为了从信号处理的角度进一步研究模式耦合颤振的存在，本文提出了一种基于两个颤振类型指标（CTI）来确定颤振机制的新方法，其中两个颤振类型指标由真模数（NTM）和特征乘数（DCM）的分布。通过Mathieu方程的仿真，通过动态模态分解（DMD）得到了NTM和DCM，并证明可以有效地区分模态耦合颤振和再生颤振的响应信号。通过机器人铣削实验和Spearman相关分析，推论机器人铣削中不存在模态耦合颤振。