Design and experiment of a universal two-fingered hand with soft fingertips based on jamming effect

The goal of robotic manipulators is to grasp objects of irregular shapes with better precision and efficiency. Universal grippers developed in recent years are designed with excessive complexity or lower resistance to damage. In this paper, we propose the idea of a universal parallel-fingered hand with soft fingertips based on jamming effect, in which negative pressure and particle flow are utilized to achieve variable stiffness. Then we set up a whole pick-and-place experiment system to evaluate the operational performance in the real serving situations. The results indicate that for most rigid objects, our prototype with soft fingertips, the stiffness of which is over the threshold to bear maximum task load after jamming, can demonstrate higher grasping stability than rigid ones, reduce around 40% motor drive power consumption and have a higher load capacity compared with the rigid-fingertip prototype under stable grasping, and have a relatively better operating precision of ± 0.62 mm compared to most of previous soft grippers when placing objects with equal weight. The findings can facilitate to improve the grasping precision of mechanical hands with soft fingertips.