Design and Experiment of Magnetorheological Smart Gripper for Non-destructive Tomato Grasping

Abstract:

In order to realize non-destructive and fast grasping of soft and fragile spherical fruit, tomatoes were taken as the research object, and a type of flexible contour-profiling smart gripper was designed based on magnetorheological (MR) fluid smart materials. At first, the structure of the smart gripper was designed according to the size parameters of tomato. The smart MR gripper mainly consisted of four parts: the base, the electric parallel driving part, the connecting plate and the MR module. The MR fluid was constrained by a flexible film in the MR module, which can flexibly and tightly fit the surface of the tomato fruit, thereby achieving non-destructive grasping. Then the rationality of the mechanical structure of the MR module was verified by finite element simulation, and the optimal dimensional configuration was determined. To determine how the applied current and set position affected the gripper stiffness and maximum grasping quality, the stiffness test and standard sphere grasping test were carried out. The results showed that the current was positively correlated with the gripper stiffness and maximum grasping quality, while the position was negatively correlated with the maximum grasping mass and positively correlated with the gripper stiffness. Finally, in order to verify the actual grasping performance of the gripper, the tomato grasping test was carried out. The test results showed that the success rate was 100%, the direct damage rate of grasping was 0, and the average task time was 5.39s, indicating that the gripper could quickly and non-destructively grasp tomatoes of different sizes.