US Patent 9120230 Gripping and releasing apparatus and method

A passive universal gripper includes a mass of granular material encased in an elastic membrane. Using a combination of positive and negative pressure, the gripper can rapidly grip and release a wide range of objects that are typically challenging for conventional universal grippers, such as flat objects, soft objects, or objects with complex geometries. The gripper passively conforms to the shape of a target object, then vacuum-hardens to grip it rigidly; later using positive pressure to reverse this transition—releasing the object and returning to a deformable state. The apparatus and method enable the fast ejection of objects from the gripper, as well as essentially instantaneous reset time between releasing and gripping.