Print Email Facebook Twitter Sparse Magnetometer-free Inertial Motion Tracking - A Condition for Observability in Double Hinge Joint Systems Title Sparse Magnetometer-free Inertial Motion Tracking - A Condition for Observability in Double Hinge Joint Systems Author Eckhoff, Karsten (Technical University of Berlin) Kok, M. (TU Delft Team Manon Kok) Lucia, Sergio (Technical University of Berlin) Seel, Thomas (Technical University of Berlin) Date 2021 Abstract Inertial measurement units are commonly used in a growing number of application fields to track or capture motions of kinematic chains, such as human limbs, exoskeletons or robotic actuators. A major challenge is the presence of magnetic disturbances that results in unreliable magnetometer readings. Recent research revealed that this problem can be overcome by exploitation of kinematic constraints. While typically each segment of the kinematic chain is equipped with an IMU, a novel approach called sparse inertial motion tracking aims at inferring the complete motion states from measurements of a reduced set of sensors. In the present contribution, we combine the magnetometer-free and the sparse approach for real-time motion tracking of double-hinge joint systems with non-parallel joint axes. Analyzing the observability of the system, we find a condition which assures that the relative orientations between all segments are uniquely determined by a kinematic constraint, which contains only the gyroscope readings. Furthermore, we propose a moving-horizon estimator and validate it in a simulation study of four movements, which differ by their degrees of excitation. The results of this study confirm the theoretical conjectures and demonstrate that magnetometer-free sparse inertial real-time motion tracking is feasible under precise and simple excitation conditions. Subject inertial sensorskinematic constraintsmotion estimationmoving horizon estimationnonlinear systemsObservabilitysensor networks To reference this document use: http://resolver.tudelft.nl/uuid:e965b9fd-0150-4072-a3b3-86615f3ae9e3 DOI https://doi.org/10.1016/j.ifacol.2020.12.403 ISSN 1474-6670 Source IFAC-PapersOnLine, 53 (2020) (2), 16023-16030 Event 21st IFAC World Congress 2020, 2020-07-12 → 2020-07-17, Berlin, Germany Part of collection Institutional Repository Document type journal article Rights © 2021 Karsten Eckhoff, M. Kok, Sergio Lucia, Thomas Seel Files PDF 1_s2.0_S2405896320306923_main_1.pdf 1.09 MB Close viewer /islandora/object/uuid:e965b9fd-0150-4072-a3b3-86615f3ae9e3/datastream/OBJ/view