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Conference papers

Computing the positioning error of an upper-arm robotic prosthesis from the observation of its wearer's posture

Alexis Poignant 1, 2, 3 Mathilde Legrand 1, 2, 3 Nathanael Jarrassé 1, 2, 3 Guillaume Morel 1, 2, 3
1 AGATHE - Assistance aux Gestes et Applications THErapeutiques
ISIR - Institut des Systèmes Intelligents et de Robotique, INSERM - Institut National de la Santé et de la Recherche Médicale : U1150
Abstract : When the arm prosthesis worn by an amputated Human being is not adequately configured with respect to the end-effector task, body compensations are often observed. Namely, to compensate for a wrong joint positioning on the robotic distal side, a subject trying to reach a desired position/orientation of his/her hand mobilizes his/her proximal joints, thus exploiting the redundancy of the human+robot kinematic chain. In this paper, we explore the possibility of exploiting this well-known behavior to reverse the causality: if we observe the posture of an amputated subject wearing a prosthesis during a hand positioning task, to what extent can we infer the positioning error of the prosthesis? To answer this question, we make the assumption that the adequate, or natural posture for a given task is one that optimizes a postural score. The proposed approach then consists in i) measuring the joint posture of the subject fitted with the prosthesis; ii) search for an alternative posture that optimizes a postural score within the null space of the human+robot kinematic chain and iii) compute the position error for the robot joints between the initial and the optimized posture. An experimental evaluation is provided with non amputated subjects who emulate erratic positioning of their distal joints during hand positioning tasks. Results show that joint errors are estimated with a precision that seems compatible with the implementation of a real time control algorithm.
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Contributor : Nathanael Jarrasse Connect in order to contact the contributor
Submitted on : Thursday, June 3, 2021 - 5:21:44 PM
Last modification on : Friday, January 14, 2022 - 9:46:03 AM
Long-term archiving on: : Saturday, September 4, 2021 - 7:29:29 PM


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Alexis Poignant, Mathilde Legrand, Nathanael Jarrassé, Guillaume Morel. Computing the positioning error of an upper-arm robotic prosthesis from the observation of its wearer's posture. 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021, Xi'an, China. ⟨10.1109/ICRA48506.2021.9561613⟩. ⟨hal-03248786⟩



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