基于柔性齿条机构的变刚度关节驱动器的设计与研究

During the autonomous operation in the unstructured environment or the co-operation with people, human-robot safety, high dynamic performance and energy saving of robots are some research hotpots in the robotics field. The Variable Stiffness Joint Actuator(VSJA), having a flexible element in series with the output end of the rigid reducer, can regulate the robot's joint stiffness to meet the task requirements and upgrade its adaptability, which plays an important role in expanding the application field of service robots and specialized robots. The mechanics model of VSJA with the Flexible Toothed Rack (FTR) mechanism can be abstracted as the statically indeterminate beam with double clamped constraints and variable point of force，and the joint stiffness turns to be proportional to the square of the displacement of the stiffness regulating gear with respect to FTR. This project plans to research the working principles of VSJA with FTR, analyze its static and dynamic performance and minimize the energy consumption. Through the theoretical analysis and experiments with the physical prototype, Three aspects on the mechanism of stiffness adjusting, the intrinsical relation between the biologically variable stiffness and physically variable stiffness and the scientific principle between stiffness regulation and energy consumption will be investigated, which proposes the designing method and theoretical support to develop the new generation of robotic VSJA.

在非结构环境下自主作业或进行人机协作时，机器人的安全性、动态特性和节省能量是领域内的研究热点。变刚度关节驱动器在刚性减速器输出端串联一个刚度可调的弹性环节，可实时调节机器人的关节刚度，提高机器人的适应性，对扩大服务机器人和特种机器人的应用领域具有重要意义。基于柔性齿条机构的变刚度关节驱动器的力学模型为两端固支的、受力点可变的静不定弹性梁，且关节刚度与调节位移的平方成正比。本项目计划研究该种变刚度关节驱动器的工作机理，开展静力学分析、动力学建模和最小能量消耗等方面的科学研究。通过理论分析和样机试验，力争在变刚度机构、生物变刚度与物理变刚度之间的内在联系、刚度控制与最小能量消耗的科学关系等三个方面取得突破，为新一代机器人变刚度关节驱动技术提供设计方法和理论依据。

本项目为国家自然科学基金青年基金资助，项目执行期为2014年1月至2016年12月。本项目的研究内容是基于柔性齿条机构的变刚度关节驱动器的设计与研究。本项目提出和实施的变刚度关节驱动器采用柔性齿条机构作为刚度调节机构，其特点是：弹性环节和调节机构合二为一。在同等关节刚度调节范围内，其结构尺寸、刚度调节功率分别比已有关节驱动器小约20%，80%。这一研究成果大大降低了关节驱动器的物理尺寸和自重，对将来的多变刚度关节机器人应用具有重要意义。本项目还建立了变刚度关节驱动器的动力学模型。通过位置阶跃和击球实验验证了动力学模型的正确性。研究表明该变刚度关节驱动器具有一定的爆发性，特别是在关节加速阶段，关节爆发力不仅与关节刚度有关，还与击球时机有关。这一研究结论是对已发表文献中的定性结论做了定量的补充验证，特别是在关节加速运动阶段，小球的飞行距离主要由关节驱动器的刚度和击球时机共同决定。本项目在变刚度机构和变刚度关节驱动器动力学特性方面的研究为提升与人共融机器人的动态特性提供了理论依据。