Vibration Measurement and Analysis of Rotary Tools Using Millimeter-wave Sensor

Vibration measurement of rotary cutting tools is of great significance in machining accuracy control and process stability monitoring. Several undirect and direct techniques such as accelerometers and laser vibrometry have been developed for this issue, but each has its own limitations. In this article, a novel direct measurement approach, termed close-range micro-amplitude millimeter-wave vibration measurement (CMMV), is proposed to achieve reliable and accurate vibration displacement measurement of rotary tools. In CMMV, to accurately quantify the tiny vibration of rotary tools with a compact and low-cost single-frequency millimeter-wave sensor in a short range, the critical near-field amplitude modulation effect, DC offset and I/Q imbalance are decoupled and determined with comprehensive calibration including pre-motion and parameter optimization. To this end, the detailed method and implementation procedures are established, following with the further characteristic analysis for extracting the eccentricity error and roundness error. Experimental validations with various scenarios show that the proposed method has high accuracy with μm level, offering a promising approach for vibration measurement of rotary tools with online monitoring.