Assembly Lines
New Gripper Moves Multiple Objects at Once
A new multi-object gripper (right) can improve the efficiency of pick-and-place applications.
Illustration courtesy Seoul National University/Science Robotics
SEOUL—Engineers at the Seoul National University have developed a gripper that can move multiple objects. MOGrip picks up objects one by one and moves them all at once, like a human. The gripper not only transfers multiple objects at once, but also places individual objects at desired locations.
“Unlike humans, conventional gripper designs have predominantly focused on transferring a single object at a time,” says Kyu-Jin Cho, Ph.D., a professor of mechanical engineering and director of the Soft Robotics Research Center. “While grippers for multi-object grasping have been developed, they typically consist of multiple small grippers arranged at the end of a robotic arm, restricting their use to highly structured environments.”
To transfer multiple objects in unstructured environments, humans grasp individual objects with their fingers and translate them to the palm for storage. This action is known as finger-to-palm translation.
MOGrip features fingers that can translate objects and a conveyor palm for storing multiple items simultaneously. The fingers, powered by two motors, grasp objects and transfer them to the palm. Decoupling links in the fingers kinematically separate the grasping and transferring motions, simplifying their control.
The conveyor palm is designed as a pair of belts with elastic hairs embedded on their surfaces. The belts are actuated by a single motor. When the belts rotate, objects are inserted between the hairs, enabling the simultaneous storage and transfer of multiple objects.
During experiments, Cho and his colleagues discovered that eight objects on a shelf could be transferred with just two reciprocating motions. Compared to single-object grasping, this reduced process time by 34 percent and the robotic arm’s travel distance by 71 percent.
“The principles of nature provided inspiration for efficient robotic motion and actuation strategies,” says Cho. “Finger-to-palm translation and palm-to-finger translations are a key component of the multi-object grasping strategy, and [our] gripper is the first example of applying this principle to a robot.”
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