title: Online Kinematic and Dynamic-State Estimation for Constrained Multibody Systems Based on IMUs.
abstract: This article addresses the problems of online estimations of kinematic and dynamic states of a mechanism from a sequence of noisy measurements. In particular, we focus on a planar four-bar linkage equipped with inertial measurement units (IMUs). Firstly, we describe how the position, velocity, and acceleration of all parts of the mechanism can be derived from IMU signals by means of multibody kinematics. Next, we propose the novel idea of integrating the generic multibody dynamic equations into two variants of Kalman filtering, i.e., the extended Kalman filter (EKF) and the unscented Kalman filter (UKF), in a way that enables us to handle closed-loop, constrained mechanisms, whose state space variables are not independent and would normally prevent the direct use of such estimators. The proposal in this work is to apply those estimators over the manifolds of allowed positions and velocities, by means of estimating a subset of independent coordinates only. The proposed techniques are experimentally validated on a testbed equipped with encoders as a means of establishing the ground-truth. Estimators are run online in real-time, a feature not matched by any previous procedure of those reported in the literature on multibody dynamics.
authors.affiliation: Department of Engineering, Automatic Control, Robotics and Mechatronics Research Group, University of Almería, Agrifood Campus of International Excellence (ceiA3), CIESOL, Joint Center University of Almería-CIEMAT, Almería 04120, Spain. jltmoreno@ual.es.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Torres-Moreno
authors.affiliation: Department of Engineering, Automatic Control, Robotics and Mechatronics Research Group, University of Almería, Agrifood Campus of International Excellence (ceiA3), CIESOL, Joint Center University of Almería-CIEMAT, Almería 04120, Spain. joseluisblancoc@gmail.com.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Blanco-Claraco
authors.affiliation: Department of Engineering, Automatic Control, Robotics and Mechatronics Research Group, University of Almería, Agrifood Campus of International Excellence (ceiA3), CIESOL, Joint Center University of Almería-CIEMAT, Almería 04120, Spain. agimfer@ual.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Giménez-Fernández
authors.affiliation: Mechanical Engineering Laboratory, University of A Coruña, Escuela Politécnica Superior, Mendizábal s/n, Ferrol 15403, Spain. emilio.sanjurjo@udc.es.
authors.forename: Emilio
authors.initials: E
authors.lastname: Sanjurjo
authors.affiliation: Mechanical Engineering Laboratory, University of A Coruña, Escuela Politécnica Superior, Mendizábal s/n, Ferrol 15403, Spain. minaya@udc.es.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Naya
keywords: Kalman filter; dynamics of multibody systems; inertial measurement units; kinematics; simulation; state estimation; testbed