Rocking motion is often a significant source of uncertainty in sinusoidal calibrations of accelerometers and force transducers. We describe real-time measurements of rocking during sinusoidal excitation, performed at NIST. The measurement is contactless and can be performed simultaneously with the motion. We report rocking measurements for excitation frequencies up to 2 kHz. The results obtained have an absolute uncertainty (k = 2) in the range of 0.02 µrad to 3.3 µrad and allow error due to rocking motion to be largely corrected in axial acceleration measurement.

This contribution proposes a methodology to predict the transfer function of an accelerometer solely based on an electrical impedance measurement. Such impedance measurement can be conducted in-situ and has certain advantages for some types of accelerometers and under certain measuring conditions. A proof-of-concept study has been conducted where the methodology is used to estimate the sensitivity at 160 Hz, the proposed method underestimates the sensitivity by 9% compared to a conventional vibration experiment.

Low uncertainty Kibble balance measurements require careful consideration of the effect of external sources of vibration. This paper compares vibrational modelling of the machine frame of the National Physical Laboratory’s next generation Kibble balance using three different software packages. The output of the modelling on the machine frame showed that the first modes of vibration were all above the design requirement of 60 Hz.
The model was then enhanced to include the moving section of the balance modelled with two types of guidance mechanism. The output from the modelling showed a reduction in the resilience of the balance to lateral vibrations but the linkage type guidance mechanism was still resilient to induced vibrations at frequencies up to 50 Hz.

This paper describes an absolute time-based concept to simultaneously calibrate a large number of MEMS sensors using Ethernet as communication interface and investigates new uncertainty influences related to the absolute time base.

This paper describes geometric design consideration for the creation (manufacture) of a tri-axial accelerometer intended for the validation of multi axis calibration systems that implements simultaneous axis calibration methods. Two mounting geometries were investigated, and the results obtained using them are reported. The one configuration, a cube with counterweights. The second configuration see the accelerometers mounted on “recessed” faces, aiming at placing (aligning) the individual accelerometers close to the vibration excitation vector.