ALEXANDRIA, Va., Feb. 3 -- United States Patent no. 12,539,574, issued on Feb. 3, was assigned to FANUC Corp. (Yamanashi, Japan).
"Sensorless chatter detection" was invented by Yen Po Liu (Union City, Calif.) and Tetsuaki Kato (Fremont, Calif.).
According to the abstract* released by the U.S. Patent & Trademark Office: "A sensorless method for machine tool chatter detection. When the machine tool spindle is running, a spindle motor torque signal is analyzed in the time domain to determine whether a bit is currently cutting a workpiece. When not cutting, an air-cut reference signal is stored for later use. When cutting, the spindle motor torque signal, along with positioning servo motor signals, are converted to the frequency domain and fi...