Modeling and Analysis of Physical Human-Robot Interaction of an Upper Body Exoskeleton in Assistive Applications

Portable exoskeletons can be used to assist elderly or disabled people in their daily activities. The physical human-robot interaction is a major concern in exoskeleton development for both functioning properly and interacting safely and comfortably. Using a model of the human musculoskeletal system and the exoskeleton can help better understanding, estimating and analyzing the physical human-robot interaction. In this paper, a model comprising the biomechanics of human upper body and the dynamics of a 4-DoF exoskeleton, named UB-AXO, is developed and used to study the physical human-robot interaction. The human-exoskeleton model is able to estimate effect of physical human-exoskeleton interaction, such as muscle activity, and energy consumption and human joint reaction forces, when performing cooperative motions with the exoskeleton. The model development is described and subsequently two simulation studies of typical activities of daily living are conducted to analyze and evaluate the performance of the UB-AXO. The simulation results demonstrate that the UB-AXO is able to reduce muscle loading and energy consumption, while maintaining a safe physical human-exoskeleton interaction.