A quantitative comparison of a position measurement system and accelerometry

An electro-mechanical system to characterize the dynamic performance of a position measurement system was constructed. The system produced pure sine wave kinematics over the frequency range of 1-11 Hz. Synchronous measurements of the position (using infra-red light emitting diodes) and the acceleration were taken at discrete frequencies. The position signal was filtered and differentiated twice to obtain an estimated acceleration. The acceleration estimate was compared to the acceleration reading from the accelerometer, and both were compared to the theoretical acceleration. The comparison was based on extracting average features of the signal like amplitude, offset and noise. The results show that the accelerometer measurements matched the theoretical amplitude to within 1-3% over most of the range but showed significant offset drift. The acceleration estimates based on the position measurements were highly dependent on the filtering scheme, showed no significant offset but had higher levels of noise. The experimental measurements and the mathematical analysis quantitatively compared the dynamic performance of the position measurement system and the accelerometer. Such a system could be used to optimize the performance of position measurement devices, by comparing different filtering and/or differentiating schemes.