Real-time curvature estimation of printable soft gripper using electro-conductive yarn

Automatic handling of many types of food materials are required to realize the automation of production of commercially prepared box lunches. A printable soft gripper was developed for food handling which is simple to produce with a 3D printer. However, the sensing ability of the printable soft gripper was not discussed in previous research. In this paper, a novel method for estimating the curvature of a printable soft gripper using electro-conductive yarn is presented. Electro-conductive yarn is a conductive material, and the resistance of strings is changed by stretching. It is less expensive than other sensors that can be used for curvature measurement. Additionally, it is easy to assemble and disassemble by hand. Electro-conductive yarn is applied to a prototype printable soft gripper, and the proposed estimation method is verified experimentally. From the experimental results, the estimated curvature from the resistance of the electro-conductive yarn coincide with the actual curvature of the gripper. Our proposed method of using electro-conductive yarn was successful for estimating the curvature of a printable soft gripper.