A Gripper Capable of Grasping, Caging, and Pressing for Food Decoration

Food decoration usually requires a robotic system to perform multiple motions such as grasping, reorientation, and pushing. In this study, a novel gripper capable of grasping, caging, and pressing was developed with two-degrees-of-freedom featuring a parallel-drive mechanism and actively rotatable fingers. By employing two motors and two rack-and-pinion mechanisms, the system enables the simultaneous opening-closing and rotational motions of multiple fingers. This enables the grasping and caging of a target object. With the help of the inverted V-shaped fingers, the gripper can realize pressing motion after placement for stabilizing food decoration. To control the gripper, a kinematic model was derived to relate motor motions to finger motions. Experiments were conducted to decorate chestnuts on a dorayaki and the results revealed that a pressing motion is essential for stable decoration. Additionally, experiments on grasping various fragile food items demonstrated the effectiveness of the caging motion.