Adaptive three-finger grippers using a single actuator

Existing robotic hands with dozens of motors can grasp various objects through dexterous motion, but they are difficult to fabricate and control, and have relatively low durability. By contrast, a two-finger gripper can grasp objects by using a single motor and simple control algorithms, but it cannot grasp long or spherical objects. The grippers used in service fields should preferably have the elements of a single motor, simple control, and the ability to grasp a variety of objects. In this study, we propose an adaptive three-finger gripper with an underactuated mechanism that can grasp objects with complex shapes by using a single motor and simple control commands. The proposed gripper is designed to stably grasp objects of complex shapes with its fingers that use magnetic-gear-based belt drive mechanism and passive joints. A series of experiments showed that adaptive grasping of objects having complex shapes is possible, and even long objects can be grasped firmly.