Optical and inertial motion capture joint angle comparison using Jack™

Abstract

Current digital ergonomic simulation processes utilize a single posture within a workstation to evaluate the risk of injury, however there is a desire from the manufacturing industry to move towards full dynamic human ergonomic simulations. These dynamic simulations would benefit ergonomists and engineers by allowing for evaluation of tasks completed within an entire workstation. However, dynamic simulations require a great time commitment, on behalf of the user, to complete. Motion capture technology can be used to reduce the users time; however, the gold standard optical-based technology is limited to laboratory-based examinations. Inertial-based capture technologies might be a solution as it would allow for direct capture of the workers within the manufacturing environment, however this technology needs to be assessed for accuracy. Twenty participants completed four multi-task events simulating real work, in a laboratory, while instrumented with inertial and optical based motion capture systems. The collected kinematic data was used to drive the motions of a digital Jack™ manikin within its digital environment, and comparisons between joint angles produced from the software were conducted between the optical system and two inertial systems. Results indicate significant joint angle error relative between the optical system and the inertial systems, however, one of the systems showed less error than the other. These errors can impact overall accuracy and representation of work within a human modeling environment.