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Measuring the Frequency Response Functions (FRF) at the tool-tip is essential for the identification of chatter-free machining conditions. The tool-tip FRF in CNC machines are usually measured by impulse hammer tests in idle conditions, and the measured FRF remain relatively unchanged under operational conditions. This method is not effective in robotic machining, because the robot’s vibration response in idle and operational conditions are significantly different. The robot’s vibration response is pose-dependent and nonlinear and therefore strongly dependent on the operational conditions. This paper presents new methods for measuring the TCP (tool-tip) FRF of machining robots under operational conditions. In-process FRF are measured by leveraging the milling forces as the excitation source, and two approaches are proposed to achieve broadband, uncorrelated, and sufficiently exciting forces: i) milling of …