Abstract: Soft grippers have great potential applications in daily life, since they can compliantly grasp soft and delicate objects. However, the highly elastic fingers of most soft grippers are prone to separate from each other while grasping objects due to their low stiffness, thus reducing the grasping stability and load-bearing capacity. To tackle this problem, inspired from the venus flytrap plant, this work proposes a mutual-hook mechanism to restrain the separation and improve the grasping performance of soft fingers. The novel soft gripper design consists of three modules, a soft finger-cot, two Soft Hook Actuators(SHAs) and two sliding mechanisms. Here, the soft finger-cot covers on the soft finger, increasing the contact area with the target object, two SHAs are fixed to the left and right sides of the finger-cot, and the sliding mechanisms are designed to make SHAs stretch flexibly. Experiments demonstrate that the proposed design can restrain the separation of soft fingers substantially, and the soft fingers with the finger-cots can grasp objects three times heavier than the soft fingers without the proposed design. The proposed design can provide invaluable insights for soft fingers to restrain the separation while grasping, thus improving the grasping stability and the load-bearing capacity.

Key words: Soft robotics , · Soft bionic finger-cot , · Soft hook actuator , · Grasping stability , · Load-bearing capacity