面向番茄无损抓取的磁流变智能手爪设计与试验

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

摘要:

为实现柔软、易损球形果实的无损、快速抓取，以番茄为研究对象，基于磁流变液智能材料设计了一种新型柔性仿形智能手爪。首先根据番茄的尺寸参数设计智能手爪的结构，磁流变智能手爪由底座、电动平行驱动部件、连接件、磁流变模块4部分组成，其中磁流变模块采用柔性薄膜约束磁流变液，能够柔顺并紧密地贴合番茄果实表面，进而实现无损抓取。其次，通过有限元仿真验证了磁流变模块机械结构的合理性，并确定了最优的尺寸构型。为明确设定电流、位置与手爪刚度、最大抓取质量之间的关系，进行了刚度测试试验和标准球体抓取试验，结果表明电流与手爪刚度、最大抓取质量呈正相关，位置与手爪最大抓取质量呈负相关，与手爪刚度呈正相关。最后，为验证手爪抓取性能，开展了番茄抓取试验。抓取试验结果表明，所设计的柔性仿形智能手爪抓取成功率为100%，抓取直接损伤率为0，平均抓取时长为5.39s，能够快速且无损地抓取不同规格的番茄。

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.