Using human studies to analyze capabilities of underactuated and compliant hands in manipulation tasks

We present a human-subjects study approach that supports the analysis of the manipulation performance of robotic hands that have the same morphology but different actuation and compliance. Specifically, we use this approach to analyze three different types of hands (one underactuated, one fully actuated, one fully actuated with compliant distal joints) as they are used to perform two manipulation tasks. The first task uses a power grasp (spraying with a spray bottle), the second a precision grasp (tracing a line on a bowl with a pen). We show that compliance in the distal joints significantly improves performance and task completion. We also show that humans choose significantly different poses for the same task when using a fully-actuated versus underactuated hand, which also results in superior task performance. Our results suggest that humans use a combination of under-actuated and fully-actuated techniques, which when used on robotic systems would also improve their performance on manipulation tasks.