Title: Enhanced optimisation-based inverse kinematics methodology considering joint discomfort

Authors: Yujiang Xiang, Salam Rahmatalla, Jasbir S. Arora, Karim Abdel-Malek

Addresses: Virtual Soldier Research (VSR) Program, Center for Computer Aided Design (CCAD), The University of Iowa, Iowa City, IA 52242, USA. ' Virtual Soldier Research (VSR) Program, Center for Computer Aided Design (CCAD), The University of Iowa, Iowa City, IA 52242, USA. ' Virtual Soldier Research (VSR) Program, Center for Computer Aided Design (CCAD), The University of Iowa, Iowa City, IA 52242, USA. ' Virtual Soldier Research (VSR) Program, Center for Computer Aided Design (CCAD), The University of Iowa, Iowa City, IA 52242, USA

Abstract: This paper presents an optimisation-based inverse kinematics (IK) method to compute realistic joint angles from marker-based positional data of a highly redundant three-dimensional digital human model. The effects of skin movement artefact and spine-shoulder joint coupling are alleviated by augmenting the optimisation problem with a skeletal discomfort function which is applied to the spine-shoulder-neck region only. The discomfort function ensures natural movement and avoids extreme joint motion. A key feature of the proposed error-minimisation-based method is that the error of the joint centre positions are not only minimised in the objective function, but also considered in the constraints so that the motion capture motion can be tracked more accurately. The methodology is demonstrated by three numerical examples, including vehicle-braking, throwing, and sprinting. The results showed that the proposed method is approved to be numerically stable and efficient to convert the motion capture data into joint space for a large-scale digital human model. Finally, the IK results are verified with the Visual3d software from C-motion.

Keywords: inverse kinematics; multi-objective optimisation; motion capture; skeletal discomfort; model validation; joint discomfort; 3D digital human models; modelling; skin movement; spine-shoulder joint coupling; spine, shoulder; neck; vehicle braking; throwing; sprinting; joint space.

DOI: 10.1504/IJHFMS.2011.041640

International Journal of Human Factors Modelling and Simulation, 2011 Vol.2 No.1/2, pp.111 - 126

Published online: 28 Jul 2011 *

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