Ambulatory l5/s1 moment estimation during manual lifting using wearable sensors: bottom-up versus top-down approach

In this validation study we investigated the L5/S1 moment estimation performance of an ambulatory measurement system: inertial measurement suit (Xsens) and instrumented force shoes. A top-down (starting at hands) and a bottom-up (starting at feet) inverse dynamic approach were tested. As a reference, a laboratory measurement system was used: optical motion capture system and force plates. The top-down (RMS< 15Nm) approach performed much better than the bottom-up approach (RMS up to 49Nm). In the bottom-up approach, small position errors at the feet result in high moment errors because of the high ground reaction forces.