The goal of the present paper is to investigate inertial measurement systems for the ability to reconstruct the short time rigid body motion of objects, e.g. clumps in snow avalanches. While strapdown inertial navigation is well established, special algorithms are needed for the accurate motion reconstruction for short time motion with partially known boundary conditions. Furthermore, low cost inertial sensors are available with the ability to log translational accelerations and angular velocities as well as magnetic flux densities, which need to be extended with respect to GPS, time synchronization, and power management functionalities. In this paper, a newly developed system to measure the motion inside snow avalanches with redundant sensors, which have significantly higher measurement ranges than systems published in the past, is presented. In addition, an algorithm for motion reconstruction from measured translational accelerations, angular velocities and magnetic flux densities is derived. Furthermore, an optimization by eliminating terminal translational velocities is presented. The developed system is tested and its function is confirmed by reproducible measurement data from two experiments on skis, whereas these experiments differ in the magnitude of rotations. The presented motion reconstruction algorithm was used to evaluate the measurement data and thus the newly developed measurement system.

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