Control of untethered soft grippers for pick-and-place tasks

In order to handle complex tasks in hard-to-reach environments, small-scale robots have to possess suitable dexterous and untethered control capabilities. The fabrication and manipulation of soft, small-scale grippers complying to these requirements is now made possible by advances in material science and robotics. In this paper, we use soft, small-scale grippers to demonstrate pick-and-place tasks. The precise remote control is obtained by altering both the magnetic field gradient and the temperature in the workspace. This allows us to regulate the position and grasping configuration of the soft thermally-responsive hydrogel-nanoparticle composite magnetic grippers. The magnetic closed-loop control achieves precise localization with an average region-of-convergence of the gripper of 0.12±0.05 mm. The micro-sized payload can be placed with a positioning error of 0.57±0.33 mm. The soft grippers move with an average velocity of 0.72±0.13 mm/s without a micro-sized payload, and at 1.09±0.07 mm/s with a micro-sized payload.