Single-Motor Robotic Gripper with Multi-Surface Fingers for Variable Grasping Configurations

This study proposes a novel robotic gripper with variable grasping configurations for grasping various objects. The fingers of the developed gripper incorporate multiple different surfaces. The gripper possesses the function of altering the finger surfaces facing a target object by rotating the fingers in its longitudinal direction. In the proposed design equipped with two fingers, the two fingers incorporate three and four surfaces, respectively, resulting in the nine available grasping configurations by the combination of these finger surfaces. The developed gripper is equipped with the functions of opening/closing its fingers for grasping and rotating its fingers to alter the grasping configuration -all achieved with a single motor. To enable the two motions using a single motor, this study introduces a self-motion switching mechanism utilizing magnets. This mechanism automatically transitions between gripper motions based on the direction of the motor rotation when the gripper is fully opened. In this state, rotating the motor towards closing initiates the finger closing action, while further opening the fingers from the fully opened state activates the finger rotation. This letter presents the gripper design, the mechanics of the self-motion switching mechanism, the control method, and the grasping configuration selection strategy. The performance of the gripper is experimentally demonstrated.