Qualitative and Quantitative Metrics for Evaluating the Resulting Acceleration in Random Positioning Machines (RPM)

The Random Positioning Machine (RPM) is a widely used method to alter the impact of gravity on biological systems by means of averaging the gravitational vector through random rotation. The aim of this work is to analyze the real motion of an RPM by qualitatively and quantitatively evaluating the resulting acceleration with regard to its averaging and uniform distribution. A scalable measuring device was developed that allows long-term measurements at several measuring points simultaneously. Acceleration averaging over time is depicted more generally for RPM motion using moving averages. The density representation on a sphere and the statistics according to Giné enable an evaluation of the distribution of gravity. The investigated metrics do not yet allow a direct statement about the suitability of simulated microgravity for biological experiments, but can serve as a basis for improvements to the RPM movement.