title: Inertial Sensor Error Reduction through Calibration and Sensor Fusion.
abstract: This paper presents the comparison between cooperative and local Kalman Filters (KF) for estimating the absolute segment angle, under two calibration conditions. A simplified calibration, that can be replicated in most laboratories; and a complex calibration, similar to that applied by commercial vendors. The cooperative filters use information from either all inertial sensors attached to the body, Matricial KF; or use information from the inertial sensors and the potentiometers of an exoskeleton, Markovian KF. A one minute walking trial of a subject walking with a 6-DoF exoskeleton was used to assess the absolute segment angle of the trunk, thigh, shank, and foot. The results indicate that regardless of the segment and filter applied, the more complex calibration always results in a significantly better performance compared to the simplified calibration. The interaction between filter and calibration suggests that when the quality of the calibration is unknown the Markovian KF is recommended. Applying the complex calibration, the Matricial and Markovian KF perform similarly, with average RMSE below 1.22 degrees. Cooperative KFs perform better or at least equally good as Local KF, we therefore recommend to use cooperative KFs instead of local KFs for control or analysis of walking.
authors.affiliation: Neural Rehabilitation Group, CSIC, Av. Dr. Arce 37, Madrid 28002, Spain. stefan.lambrecht@kuleuven.be.|Division PMA, Department of Mechanical Engineering, Katholieke Universiteit Leuven, Celestijnenlaan 300B, B-3001 Heverlee, Belgium. stefan.lambrecht@kuleuven.be.|Department of Biomedical Kinesiology, Katholieke Universiteit Leuven, Tervuursevest 101, B-3001 Heverlee, Belgium. stefan.lambrecht@kuleuven.be.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lambrecht
authors.affiliation: Department of Electrical Engineering, Federal University of São Carlos, São Paulo 13565-905, Brazil. samlourenco@gmail.com.
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Nogueira
authors.affiliation: Neural Rehabilitation Group, CSIC, Av. Dr. Arce 37, Madrid 28002, Spain. m.bortole@csic.es.
authors.forename: Magdo
authors.initials: M
authors.lastname: Bortole
authors.affiliation: Department of Mechanical Engineering, Center for Robotics of São Carlos, University of São Paulo, São Paulo 13565-905, Brazil. siqueira@sc.usp.br.
authors.forename: Adriano A G
authors.initials: AA
authors.lastname: Siqueira
authors.affiliation: Department of Electrical Engineering, Center for Robotics of São Carlos, University of São Paulo, São Paulo 13565-905, Brazil. terra@sc.usp.br.
authors.forename: Marco H
authors.initials: MH
authors.lastname: Terra
authors.affiliation: Group of Neural and Cognitive Engineering, CSIC, Ctra. de Campo Real km 0.200, Arganda del Rey 28500, Spain. e.rocon@csic.es.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rocon
authors.affiliation: Neural Rehabilitation Group, CSIC, Av. Dr. Arce 37, Madrid 28002, Spain. jose.pons@csic.es.
authors.forename: José L
authors.initials: JL
authors.lastname: Pons
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D015374:Biosensing Techniques; D016001:Confidence Intervals; D006801:Humans; D008297:Male; D008962:Models, Theoretical
keywords: Kalman Filter; biomechanics; calibration; exoskeleton; inertial sensor; motion analysis