For a good soft gripper, it is desirable to have many grasping modes, variable stiffness and high load capacity in order to adapt to all sort of target objects. However, most of the existing soft grippers only have one grasping mode and are difficult to simultaneously possess variable stiffness and high load capacity. Here, a novel enclosing soft robotic gripper is designed to have two grasping modes, stiffness-tunable and high load capacity. This design includes two integrated closed annular structures, a contraction actuator in outside inner and a particle jamming package in inside inner. This contraction actuator is divided into four driving chambers and each chamber is inflated by an air compressor to produce gripping force. The particle jamming package is deflated by a vacuum pump to produce variable stiffness. In the contraction-based grasping mode, it can adapt to all sort of target objects (arbitrary shapes and rigidities) with a wide range of payloads (spanning from 2 g of a single-use plastic cup to 36.5 kg of weights). By designing a seal structure to produces the suction-based grasping mode under vacuum pressure, it enables the gripper to adsorb objects with flat surface and various weights (up to 16 kg).
