康复机器人用弹性驱动器结构及力控制系统设计研究

发布时间：2019-03-14 12:05

【摘要】：串联弹性驱动器(Series Elastic Actuator,SEA)作为康复机器人的动力源,可以达到柔性驱动的目的,决定着整个康复机器人的柔顺性和安全性。本论文针对目前传统刚性驱动器柔性不足而带来的可穿戴性和安全性问题,在其基础上增加弹性组件,设计出了一种变刚度活塞式SEA及其力控制系统,最后运用虚拟样机技术对上述部分结论进行验证。具体研究内容如下:首先,概述国内外传统SEA结构、变刚度SEA结构以及力控制策略的研究情况。根据康复机器人的工作要求和人体肌肉的刚度加强型特征,在传统固定刚度SEA结构的基础上,提出了一种变刚度活塞式SEA样机方案;并对传统SEA和活塞式SEA在紧凑性方面进行比较,并在受径向或轴向载荷时进行了有限元强度分析,得出活塞式变刚度SEA具有结构紧凑、承载能力较强、环境适应性强等特点。其次,以单刚度SEA力学模型为研究对象,根据两种基本控制策略如位置源和力源,分别进行了开环和闭环频域比较和分析,探讨了弹簧刚度、等效质量等参量对系统稳定性、快速性以及驱动带宽的影响;最后对双串联SEA和单刚度SEA的抗冲击性能进行频域比较分析。分析结果得出力源控制法在各方面的性能比位置源要理想,且双串联SEA在高频信号冲击时,比单刚度SEA具有更强的抗冲击性能。然后,以肘关节为例,根据不同工况建立了SEA系统的动力学模型,经简化分析后提出了控制方案,并设计了干扰反馈调节系统;考虑外界扰动,对比分析系统的阶跃响应变化情况;对干扰观测器的可行性以及带有干扰观测器的SEA力控制系统的响应能力进行了证明。所得结果证明了此系统具备很强的抗干扰性能,能快速响应输入且精度较高。这些数学模型为设计实际的物理环节,构建真实的力伺服控制系统奠定了基础。最后,通过Adams和matlab/simulink进行联合仿真,搭建了SEA虚拟样机仿真平台,验证了力源控制模型两大特性(力输出特性和输出阻抗),并对SEA驱动端速度/位移跟随特性进行分析。与直接做物理样机实验相比,虚拟样机技术节约成本,为SEA的力控制设计奠定理论基础,对于实践和生产具有指导意义。
[Abstract]:As the power source of rehabilitation robot, series elastic actuator (Series Elastic Actuator,SEA) can achieve the purpose of flexible drive, which determines the flexibility and safety of the whole rehabilitation robot. In this paper, a variable stiffness piston type SEA and its force control system are designed to solve the wearability and safety problems caused by the lack of flexibility of the traditional rigid actuators, on the basis of which the elastic components are added, and a variable stiffness piston type piston actuator and its force control system are designed. Finally, the virtual prototype technology is used to verify the above conclusions. The concrete research contents are as follows: firstly, the research situation of traditional SEA structure, variable stiffness SEA structure and force control strategy at home and abroad are summarized. According to the working requirement of rehabilitation robot and the stiffened character of human muscle, based on the traditional fixed stiffness SEA structure, a variable stiffness piston type SEA prototype is proposed. The compactness of traditional SEA and piston SEA is compared, and the finite element strength analysis is carried out when subjected to radial or axial load. It is concluded that piston variable stiffness SEA has the characteristics of compact structure, strong bearing capacity and strong environmental adaptability. Secondly, taking the single stiffness SEA mechanical model as the research object, according to two basic control strategies, such as position source and force source, the open-loop and closed-loop frequency domain comparison and analysis are carried out respectively, and the spring stiffness, equivalent mass and other parameters to the stability of the system are discussed. The influence of speed and driving bandwidth; Finally, the impact resistance of double series SEA and single stiffness SEA is compared in frequency domain. The results show that the performance of the force source control method is better than that of the position source, and the impact resistance of the double series SEA is stronger than that of the single stiffness SEA when the high frequency signal is impacted. Then, taking elbow joint as an example, the dynamic model of SEA system is established according to different working conditions. After simplified analysis, the control scheme is put forward, and the disturbance feedback regulation system is designed. Considering the external disturbance, the step response of the system is compared and analyzed, and the feasibility of the disturbance observer and the response ability of the sea force control system with the disturbance observer are proved. The results show that the system has strong anti-jamming performance, fast response to input and high precision. These mathematical models lay the foundation for designing the actual physical link and constructing the real force servo control system. Finally, the simulation platform of SEA virtual prototype is built through the joint simulation of Adams and matlab/simulink. The two characteristics (force output characteristic and output impedance) of the force source control model are verified, and the velocity / displacement following characteristics of the SEA driver are analyzed. Compared with the physical prototype experiment, the virtual prototyping technology can save the cost and lay the theoretical foundation for the force control design of SEA. It is of guiding significance for practice and production.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP242

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