title: A new validation technique for estimations of body segment inertia tensors: Principal axes of inertia do matter.
abstract: The aims of this study were to: (i) establish a new criterion method to validate inertia tensor estimates by setting the experimental angular velocity data of an airborne objects as ground truth against simulations run with the estimated tensors, and (ii) test the sensitivity of the simulations to changes in the inertia tensor components. A rigid steel cylinder was covered with reflective kinematic markers and projected through a calibrated motion capture volume. Simulations of the airborne motion were run with two models, using inertia tensor estimated with geometric formula or the compound pendulum technique. The deviation angles between experimental (ground truth) and simulated angular velocity vectors and the root mean squared deviation angle were computed for every simulation. Monte Carlo analyses were performed to assess the sensitivity of simulations to changes in magnitude of principal moments of inertia within ±10% and to changes in orientation of principal axes of inertia within ±10° (of the geometric-based inertia tensor). Root mean squared deviation angles ranged between 2.9° and 4.3° for the inertia tensor estimated geometrically, and between 11.7° and 15.2° for the compound pendulum values. Errors up to 10% in magnitude of principal moments of inertia yielded root mean squared deviation angles ranging between 3.2° and 6.6°, and between 5.5° and 7.9° when lumped with errors of 10° in principal axes of inertia orientation. The proposed technique can effectively validate inertia tensors from novel estimation methods of body segment inertial parameter. Principal axes of inertia orientation should not be neglected when modelling human/animal mechanics.
authors: School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia.
authors: Marcel M
authors: MM
authors: Rossi
authors: School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia.
authors: Jacqueline
authors: J
authors: Alderson
authors: School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia.
authors: Amar
authors: A
authors: El-Sallam
authors: Department of Kinesiology, McMaster University, Hamilton, Canada.
authors: James
authors: J
authors: Dowling
authors: Mechanical, Aerospace, and Biomedical Engineering Department, University of Tennessee, Knoxville, USA.
authors: Jeffrey
authors: J
authors: Reinbolt
authors: School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia. Electronic address: cyril.donnelly@uwa.edu.au.
authors: Cyril J
authors: CJ
authors: Donnelly
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008954:Models, Biological; D009010:Monte Carlo Method; D009068:Movement; D009949:Orientation
keywords: Airborne motion; Anthropometry; Compound pendulum; Criterion method; Simulation; Validation