Mechanical Delay
Dynamic delay in the transfer of physical stimulus through a mounting bracket to a sensor element is caused by the elasticity and damping of the mechanical support. Vibration-sensing instruments exhibit structural phase lag, which results in a delay between the actual acceleration of the target and the motion registered by the sensor. This phase shift can compromise the stability of active vibration-damping systems that rely on real-time feedback.
If the bracket has insufficient stiffness, the resulting lag will cause a significant difference between the measured and actual acceleration.
Frequency Dependency
Phase delay increases as the frequency of the physical excitation approaches the resonant frequency of the mounting bracket. Designers must ensure that the natural frequency of the mounting system is well above the operating bandwidth of the sensor to minimize this delay.
Calibration Procedure
Measuring this delay requires mounting the sensor assembly on a high-frequency shaker table and comparing its phase response to a high-precision reference sensor. This characterization is performed across the entire frequency range to map the transfer function and establish the phase delay limits.
Compensation Strategy
Real-time correction algorithms can compensate for this phase delay by applying phase-lead filters to the sensor output signal. This correction is essential in high-speed control applications where precise timing is required to prevent instability.
