Dynamic Compliance of Measuring Device for Force on High-speed Rotors

High-speed rotors are often used in high-precision applications such as spindles. The force on the rotor leads to unexpected displacement and affects machining accuracy. Multi-axis force sensors are conventionally used in measuring the dynamic force on the rotor and separating electromagnetic force. However, the frequency range cannot cover high-speed applications. In this paper, a dynamic radial electromagnetic force up to 1200Hz is applied to a high-speed rotor by an electromagnetic loading device, and the reaction force is measured. Dynamic compliance and natural frequency of the measuring device is discussed, which has a great influence on the accuracy of measuring dynamic characteristics of the rotor. Firstly, a structure with higher natural frequency is proposed. Then, the dynamic compliance is analyzed by simulation and experiments. Finally, a calibration process is given to reduce the influence of the dynamic compliance. The results show that the accuracy of measurement can be improved and the frequency range of measurement increases after considering the dynamic compliance of the measuring device.