A Soft Gripper with Adjustable Stiffness and Variable Working Length for Handling Food Material

Automation of lunch box packaging is highly demanded in Japan. The large variation and fragile properties of food materials made the handling task difficult for traditional rigid robot gripper. Soft robot gripper, on the other hand, demonstrates a possibility liar handling such materials. In this paper, we proposed a soft gripper which is able to vary its stiffness and working length. A air chamber was embedded inside the cover layer of each soft finger. By inflating this chamber with different air pressures, the stiffness and working length of the soft finger can he adjusted. The soft finger was fabricated by traditional casting process. Experimental tests were conducted on the soft finger and results showed that the bending stiffness and the working length can be varied. A gripper with four of such fingers was assembled and grasping tests were performed on defrosted broccoli and chopped eggplant pieces. Results showed that the required main chamber pressure can be lower with adjusted stiffness, and therefore, it reduces the risk of destroying the broccoli.