磁流变液柔顺关节固液界面预运动微动机理及其适应性刚度控制研究

During the object operating process, the flexibility and safety are specially needed for robot. A new type of flexible robotic joint is proposed based on magnetorheological fluid technology. The proposed flexible joint possesses the flexibility and adaptability of soft robot, and keeps the rigidity and precision of traditional robot. The pre-motion and micro-motion theory of the magnetorheological transmission structure solid-fluid surface will be investigated. The variable stiffness model of the flexible joint can be established combining the mechanical behavior of the electromagnetic fluid and the parameters of joint structure. The prototype of the robotic adaptive joint based on magnetorheological fluid will be developed. And the parametric joint system model will be deduced taking into account the variable stiffness features. To control the flexible joint, the active variable stiffness model prediction control method is proposed based on MPC theory. Then, the prototype of robotic hand based on magnetorheological fluid robotic adaptive joints will be designed and manufactured. Experimental platform will be established to realize the flexible control and real-time self-adaptable stiffness control. It is predictable that the basic theory and method for the variable stiffness model and active stiffness regulation of the flexible joint can be formed, which will lay the theoretical method and technical foundation for the engineering application of the proposed flexible joint.

针对机器人在目标操作过程中的柔顺性和安全性需求，提出一种基于磁流变液的机器人柔顺关节，该关节既具有软体机器人的柔顺性和适应性，又能保持传统机器人的刚性和准确性。分析研究磁流变液传动结构的固液界面预运动/微动机理，结合磁流变液力学行为特征及关节结构参数建立柔顺关节变刚度模型，建立计及可变刚度特性的参数化关节系统模型，开发基于磁流变液的机器人柔顺关节样机，研究基于模型预测控制算法的柔顺关节主动变刚度控制方法，开发基于该柔顺关节的机械手验证系统，实现柔顺机械手抓持刚度的实时自适应控制。预期研究形成机器人柔顺关节的可变刚度模型及主动刚度调控的基本理论方法，为该柔顺关节的工程化应用研究建立理论方法及技术基础。

磁流变液在零磁场环境中表现为牛顿流体，在磁场环境中表现为黏塑性体，流变过程可逆、响应速度快。本项目以磁流变液为应用对象，深入研究了磁流变液的流变机理，分析了磁流变液的预运动/微动特性，建立了磁流变液的全域剪切应力模型，并基于磁流变液的这种可控流变特性设计开发了磁流变液柔顺关节，为实现对磁流变液柔顺关节的自适应刚度调节与柔顺控制，研究建立了磁流变液柔顺关节耦合器的I-B模型、力矩耦合模型、位置耦合模型，定义了面向磁流变液柔顺关节耦合器传动刚度的耦合刚度并建立了耦合刚度模型，提出了计及耦合刚度约束的主动柔顺双环控制策略，在位置控制环采用模糊PID控制器进行耦合位置控制，在力矩控制环采用模型预测控制方法进行耦合力矩控制。本项目还研制了磁流变液柔顺关节样机并开展了壁面摩擦特性实验、磁化饱和电流测试实验、模型参数拟合实验、耦合力矩控制实验等实验研究工作。本项目研究开发的磁流变液柔顺关节可应用于人机交互系统、易损对象操作任务、触力跟踪作业等，通过适应性刚度控制使其具有更好的柔顺性，采用基于耦合刚度约束的主动柔顺双环控制使其具备了更高的安全性。