Vacuum End Effector Equipped with an Expansion and Contraction Mechanism Using a Wound Thin Metal Plate

We propose a vacuum end effector with an expansion and contraction mechanism to realize a picking task for objects placed in a narrow space, such as a shelf. The proposed expansion and contraction mechanism consists of a tube and exoskeleton structure and is characterized by the use of a thin metal plate wound about itself to form a tubular exoskeleton. Expansion and contraction motions were realized by connecting the tube to a linear motion mechanism. The expansion and contraction mechanism can be easily extended by elastic force. In addition, the shape of the expansion and contraction mechanism is created by winding a thin metal plate around a predetermined axis, which ensures high rigidity even in the extended state. Even when an object to be picked from a shelf is located behind other objects, the end effector can efficiently hold the object because of its elongated shape and ability to freely change the position of the suction pad using a direction-changing linkage and the expansion and contraction mechanism. The developed end effector weighs about 1.46 kg and can carry a load of 0.56 kg when extended to 150 mm. Verification of the mechanism confirmed that the developed end effector is useful because it can perform the expected object-picking operation.