Resonant frequency vibrational test

A method of subjecting a component to a resonant frequency vibrational test in which the component is excited in vibration by an exciter on the basis of an exciter input signal, the method comprising:

• providing, based on measuring the vibration of the component, a target frequency signal indicative of a frequency control signal which is the phase difference between the vibration of the exciter and the vibration of the component, the vibration of the component being measured by a motion sensor;
• providing, based on measuring the vibration of the component, a target magnitude signal indicative of a magnitude control signal which is the magnitude difference between the vibration of the component and a desired magnitude value;
• and
• exciting the exciter in vibration with the smoothed exciter input signal, the exciter input signal having been adjusted by the target frequency signal and the target magnitude signal;
• in which the smoothed exciter input signal is provided by:
• smoothing the target frequency signal, and
• using the smoothed target frequency signal to adjust the exciter input signal;
• in which the smoothed exciter input signal is provided by a Hopf oscillator driven by the target frequency signal;
• in which the exciter input signal is continuously adjusted by the target frequency signal;
• in which the target frequency signal is adjusted by a proportional integral control, according to the smoothed frequency control signal;
• and
• in which the proportional integral control provides a smoothed target frequency signal.