Passive robotic gripper using a contact-based locking mechanism

Robotic end-effectors have been developed for various applications. Most of them are driven by electric or pneumatic actuator/actuators, which usually make the end-effector bulky and vulnerable due to the external cables and air tubes. In this study, we propose a novel passive robotic gripper with a locking mechanism that does not require any actuators. Locking and unlocking of the gripper fingers are performed through contact with external environment, such as ground, table, and conveyor. To facilitate gripper design, modeling of the deformed finger shape was conducted, and experimental validation was performed. A robotic gripper with eight such passive fingers were fabricated using 3D printer. Experiments were conducted to investigate the grasping capacities in terms of object size and weight. We found that the larger the object, the greater the weight capacity of the gripper, which increased significantly when the object exceeded a certain size. In addition, experiments on grasping various food products were carried out and results suggested that the proposed gripper could grasp objects with complex shapes and soft fragile properties, but damages were caused on very fragile objects due to the rigid structure of the gripper.