Evaluating spatio-temporal consistency in robotic-assisted tasks across varied gravity compensation levels

Area of Science:

• Robotics and Biomechanics
• Assistive Technology
• Human-Robot Interaction

Background:

• Robotic exoskeletons aim to assist individuals with upper-limb impairments.
• Effective control strategies must manage device and wearer arm weight without distorting natural kinematic behavior.

Purpose of the Study:

• To investigate the impact of varying weight support levels of the Harmony exoskeleton on hand spatio-temporal features and inter-joint coordination.
• To evaluate kinematic performance during a pick-and-place task under different arm support conditions.

Main Methods:

• Eight healthy subjects performed a pick-and-place task.
• Movement was analyzed across five distinct weight support levels of the Harmony exoskeleton.
• Hand spatio-temporal features and inter-joint coordination were assessed.

Main Results:

• Movement smoothness and Cartesian space planning remained unaffected by the exoskeleton.
• Decreased movement accuracy occurred at high weight support levels for movements against gravity.
• Movements propelled by gravity showed an overall drop in accuracy; inter-joint coordination was largely consistent, with exceptions in shoulder rotation.

Conclusions:

• The Harmony exoskeleton's gravity compensation has a nuanced effect on kinematic performance.
• Insights gained can inform the optimization of assistive devices for individuals with upper-limb impairments.
• Further research may refine control strategies to mitigate accuracy reductions at higher support levels.