Safe Grasping with a Force Controlled Soft Robotic Hand
This work addresses the challenge of preventing damage to fragile objects during robotic grasping, which is incremental as it builds on existing soft hand designs with added force control.
The researchers tackled the problem of safe grasping with soft robotic hands by developing a force-controlled system that uses integrated sensors and a PI controller to regulate grasping force, successfully grasping deformable objects like plastic and paper cups without dropping or deforming them.
Safe yet stable grasping requires a robotic hand to apply sufficient force on the object to immobilize it while keeping it from getting damaged. Soft robotic hands have been proposed for safe grasping due to their passive compliance, but even such a hand can crush objects if the applied force is too high. Thus for safe grasping, regulating the grasping force is of uttermost importance even with soft hands. In this work, we present a force controlled soft hand and use it to achieve safe grasping. To this end, resistive force and bend sensors are integrated in a soft hand, and a data-driven calibration method is proposed to estimate contact interaction forces. Given the force readings, the pneumatic pressures are regulated using a proportional-integral controller to achieve desired force. The controller is experimentally evaluated and benchmarked by grasping easily deformable objects such as plastic and paper cups without neither dropping nor deforming them. Together, the results demonstrate that our force controlled soft hand can grasp deformable objects in a safe yet stable manner.