高功率密度软体机械手结构解耦型变刚度驱动机理与实验研究

A large number of end effectors (robotic hands) used in robot technology play a very important role, and these soft hands actuated by smart materials have provided with potential advantages of lightweight and adaptability, so they are important interests in future. However, most researchers have investigated either its deformation driving or its variable stiffness control when a soft hand is explored, without studying a complete function and property on deformation and variable stiffness. This project takes a soft hand as research object, and puts emphasis on the design method of uncoupled structure between variable stiffness and deformation mechanism, and control method for soft hands under specific constraints, on the basis of the mechanical properties and measurement analysis of soft smart materials. Details are as follows: study the process and mechanical properties of soft smart materials, explore the method to increase the range of stiffness variation for soft unit structure, formulate the variable stiffness model of soft unit structure and driving model of unit deformation structure based on the mechanical properties; analyze the relationship between load characteristics and mechanical properties of soft finger , study the mechanism design of uncoupled structure for soft hands; investigate the matching method between load and stiffness under specific constraints, study the grasping experiment of soft hands with variable stiffness and deformation driving, and summarize the design method of soft hands. The project aims at the driving mechanism with variable stiffness and implementation method of soft hands, to provide a new theoretical principle for the design of more lightweight and smart robot.

大量应用于机器人技术中的末端执行器(机械手)具有重要的作用，智能材料驱动的软体机械手具有轻量节能和适应智能的潜在优势，是未来发展的重点方向；但目前多数学者在研究软体机械手时没有选择合适的智能材料和结构，也没有完全实现机械手的变刚度与变形驱动功能和性能。本项目以软体机械手为研究对象，基于软体智能材料力学特性的测试分析，探索一定条件下软体机械手的变刚度与变形解耦结构设计方法和抓握控制理论。具体内容包括：研究智能材料的工艺与力学特性，探索增大软体单元刚度变化范围的方法，建立软体单元的刚度模型与变形单元的驱动模型；分析负载条件与手指力学特性之间的关系，研究软体机械手的变刚度与变形解耦结构的构型设计方法；探索一定条件下负载与刚度的匹配控制机制，分析软体机械手的变刚度抓握实验，总结软体机械手的设计方法。本项目旨在研究软体机械手的变刚度驱动机理与实现方法，为设计更加轻量与智能的机器人提供新的理论基础。

采用电机、液气压驱动软体机械手存在功率密度低、体积大、噪音大等缺点，一些机械手的变刚度与变形结构存在耦合效应也增加了其控制难度。为此，本项目首先利用三种不同规格形状记忆合金(SMA)材料设计出了一款变刚度与变形解耦结构的软体机械手，其中超弹SMA材料用于制作机械手骨架结构，0.6 mm直径SMA丝用于实现变刚度功能，0.15 mm直径SMA丝用于驱动机械手弯曲形变；再者，基于Cosserat 弹性杆理论建立了柔性机械手在刚度和负载变化情况下的形变模型，并通过实验对模型进行了验证。针对SMA非线性迟滞特性对位移输出精度的影响，提出了基于逆迟滞经验模型+神经网络算法的控制方法以提高SMA驱动器的位移跟踪精度。由于刚度变化会引起处于弯曲状态的机械手发生抖动，本项目提出了刚度-形变开/闭环控制方法，有效降低了机械手抖动现象，提高了机械手整体性能；最后，课题组还以本项目为依托，研究出了柔性爬行机器人、磁吸附柔性机械手、低沸点液体驱动软体机器人等样机，为将来进一步深入研究软体机器人打下了坚实基础。项目在执行过程中进展顺利，发表了SCI收录高水平论文7篇，其中中科院JCR一区论文4篇，申请了国家发明专利3项，参加会议6次。