形状记忆合金丝编织网气动肌肉机构及其阻抗控制

气动肌肉是仿生机器人研究的重点,为此,设计了形状记忆合金丝编织网气动肌肉机构.通过等效气缸和等效动力学分析,建立了输出力模型,设计了含位置PID内环的阻抗控制,并建立了阻抗模型,通过拉氏变换和频域分析给出了稳定条件.理论分析表明,合金丝的收缩可增大气动肌肉的输出力和调节刚度.在Matlab上开展阻抗参数对柔顺性影响的仿真实验,结果表明刚度对于接触力影响最大,阻抗控制可实现接触力和位置的协调控制.     

形状记忆合金手指系统的输出力自适应控制

形状记忆合金(SMA)是智能材料中的一种,具有功率重量比大、质量轻、无噪音等特性.作为驱动器有利于结构的小型化和轻型化.然而SMA的非线性、多映射的迟滞特性严重影响了输出力的精确控制.为此,本文提出了基于扰动补偿策略的自适应控制方法用于SMA输出力的精确控制.首先,搭建了SMA驱动的手指实验装置,建立了机理模型;其次,...     

形状记忆合金驱动器的自适应滑模反步控制

形状记忆合金(SMA)作为一种智能材料,相对于传统的驱动器具有功率重量比大、驱动电压低、质量轻、干净、无噪音等特性,被广泛应用在各领域.然而,非线性、迟滞、时变等因素影响了形状记忆合金的控制精度,限制了它的应用.为此,本文提出了自适应滑模反步控制方法,用于解决精确控制问题.文中首先搭建了实验装置,建立了形状记忆合金的机理模型;然后,采用最小二乘算法辨识了模型参数;最后,基于机理模型设计了自适应滑模反步控制器.实验结果表明,本文提出的方法具有动态响应快、跟踪精度高和抗干扰能力强的特性.     

一种微小型蠕动机器人的步态分析

介绍了一种形状记忆合金(SMA)驱动的微型蠕动机器人的结构和工作原理,并对蠕动机器人的直线运动原理和转弯运动原理分别进行了详细的分析和论述。此外,还通过详细的实验对蠕动机器人步距与SMA驱动器电流的关系、蠕动机器人转弯角度与SMA驱动器电流的关系,以及蠕动机器人响应速度与SMA驱动器电流的关系进行了分析,并确定了SMA驱动器的加热电流。     

Modeling and control of McKibben artificial muscle enhanced with echo state networks

There has been a challenging work for using conventional techniques to model and control pneumatic artificial muscle (PM) due to poor knowledge and uncertainty of the process and/or complexity of the resulting mathematical model. Trying to deal with these problems, this study proposes a novel framework—Echo State Network (ESN) as a basis to implement the tasks in the PM's modeling and control. To describe the system dynamics and the external disturbance changes with time, the online ESN adaptation scheme is presented based on the recursive least squares (RLS) algorithm. Both simulation and experimental results show that the proposed procedure has better dynamic performance and strong robustness over the other typical/classical approaches.     

Modeling of shape memory alloy shells for design optimization

A three-dimensional phenomenological constitutive model for the analysis and design optimization of shape memory alloy (SMA) structures is presented. This model specifically targets the pseudoelastic behavior due to the R-phase transformation in NiTi alloys, but also applies to similar SMA materials with low hysteresis. A history-independent formulation is presented, which allows cost-effective sensitivity analysis. The possibility to efficiently compute design sensitivities is essential for enabling the use of gradient-based optimization algorithms, which will allow design optimization of complex SMA structures. The use of the constitutive model in a problem of realistic complexity is illustrated by the analysis of a SMA miniature gripper, modeled using shell elements. The sensitivity analysis of SMA structures using the presented model is addressed in an accompanying paper.     

一种空间仿生柔性机器人设计与智能规划仿真方法

针对传统空间刚体机器人存在的自由度有限和环境适应性差等缺陷,基于生物体结构提出了一种受“尺蠖”与“蛇”启发的适用于空间在轨服务的柔性机器人。首先,搭建了柔性机器人原型样机,研究了镍钛形状记忆合金（SMA）驱动器的驱动特性,设计了可视化控制界面并通过实物实验验证了机器人原型样机的可操控性。然后,设计了一种基于所提柔性机器人结构的Q学习算法和相应的奖励函数,搭建了柔性机器人仿真模型并在仿真环境中完成了基于Q学习的机器臂自主学习规划仿真实验。实验结果显示机器臂能够在较短时间内收敛到稳定状态并自主完成规划任务,表明所提出算法具有有效性和可行性,强化学习方法在柔性机器人的智能规划与控制中具有良好的应用前景。     

Bio-inspired Actuating System for Swimming Using Shape Memory Alloy Composites

The paper addresses the designs of a caudal peduncle actuator, which is able to furnish a thrust for swimming of a robotic fish. The caudal peduncle actuator is based on concepts of ferromagnetic shape memory alloy (FSMA) composite and hybrid mechanism that can provide a fast response and a strong thrust. The caudal peduncle actuator was inspired by Scomber Scombrus which utilises thunniform mode swimming, which is the most efficient locomotion mode evolved in the aquatic environment, where the thrust is generated by the lift-based method, allowing high cruising speeds to be maintained for a long period of time. The morphology of an average size Scomber Scombrus (length in 310 mm) was investigated, and a 1:1 scale caudal peduncle actuator prototype was modelled and fabricated. The propulsive wave characteristics of the fish at steady speeds were employed as initial design objectives. Some key design parameters are investigated, i.e. aspect ratio (AR) (AR = 3.49), Reynolds number (Re = 429649), reduced frequency (σ= 1.03), Strouhal number (St = 0.306) and the maximum strain of the bent tail was estimated atε= 1.11% which is in the range of superelasticity. The experimental test of the actuator was carried out in a water tank. By applying 7 V and 2.5 A, the actuator can reach the tip-to-tip rotational angle of 85°at 4 Hz.     

基于PCL的一维形状记忆合金系统的开发与应用

智能材料的发展给结构设计带来新的方向,同时也给商用有限元软件的应用迎来新的挑战.由于MSC Nastran的局限性,尚不能很好地模拟一些智能材料.结合实际工程需要,利用Patran完善的前、后处理功能及二次开发语言,将一维形状记忆合金(Shape Memory Alloys,SMA)材料系统集成到Patran中,能方便地实现在Patran中定义其材料属性和对布置有SMA的驱动结构以及复合材料结构的快速建模分析,最后利用本文系统建立SMA复合梁以及SMA丝驱动的机翼后缘模型,并进行验证,证明此模块功能的正确性和有效性.     

一种基于SMA的摆动式驱动器驱动原理及实验

在分析了形状记忆合金(SMA)弹簧电热驱动原理的基础上,对一种差动式关节型SMA驱动器进行了实验研究。实验结果表明:驱动电流和冷却条件对驱动器的摆动周期有很大的影响,增大电流会显著提高SMA驱动器的动作频率,但电流过大,易使SMA失去形状记忆功能,所以,电流应控制在一定的范围之内。驱动器的动作频率还受到冷却速度的制约,加快冷却速度也会提高驱动器的动作频率。     

基于SMA的关节驱动器的力学分析及控制

分析了一种用于水下微小型仿生机器人的形状记忆合金(SMA)关节驱动器的力学特性,并通过模糊控制的方法对其进行了实验研究。结果表明:对于物理特性呈非线性、温度滞后、时变和受温度影响很大的SMA驱动器来说,采用模糊控制的方法,能够使驱动器稳定、平滑的工作,尽管产生了轻微的超调现象,但收到了令人较为满意的效果。因此,将模糊控制方法应用于SMA驱动器的控制有一定的理论意义和应用价值。     

基于人工肌肉的仿生机器鱼关节机构设计与力学分析

在深入分析活鱼解剖结构的基础上,设计了一种人工肌肉驱动的鱼关节结构,介绍了形状记忆合金(SMA)人工肌肉元件的设计方法．对鱼的尾鳍摆动进行了力学建模,并加以简化．基于摆动过程的力矩平衡方程,对SMA驱动力矩与阻力矩、流体阻尼力矩及机构（流体）惯性力矩进行了分析,建立了各个参数之间的定量关系式．通过数据验证了模型的可靠性,为仿生机器鱼的研究提供了参考依据．     

Modeling and time delay control of shape memory alloy actuators

Shape memory alloy (SMA) actuators possess hard nonlinearities including backlash-like hysteresis and saturation. These nonlinearities result in steady-state error and limit-cycle problems when conventional controllers such as the proportional integral derivative (PID) are used for trajectory control. In this study, a dynamics for an SMA actuator was newly derived using the modified Liang's model. The derived dynamics showed continuity at the change of the phase transformation process, but the original model could not. SMA actuator characteristics could be well described using this dynamics. The derived dynamics could be also used effectively for the prediction of control performance and gain tuning of the time delay control (TDC). The dynamics consisted of first-order linear and second-order nonlinear equations. Accordingly, a control strategy was established for the TDC to regulate only the second-order nonlinear part for simplicity and for the internal closed loop to regulate the rest. The control strategy was examined from the point of view of influence of an antiwindup scheme and high gain tuning on control performance. An anti-windup scheme was essential to protect windup phenomenon and high gain tuning was effective when a temperature disturbance existed. In the robustness test, the TDC with high gains showed robustness to inertia variation and temperature disturbance in comparison with the TDC with low gains.     

形状记忆合金驱动仿生蝠鲼机器鱼的设计

研究了一种采用鳐科模式游动、柔性胸鳍摆动方式推进的形状记忆合金（SMA）丝驱动型仿生蝠鲼机器鱼．首先,对双吻前口蝠鲼游动动作进行了分析,建立了蝠鲼胸鳍柔性摆动的简化运动模型．然后对能够模仿蝠鲼肌肉动作的智能材料进行了分析．最后设计了SMA 丝驱动的柔性仿生胸鳍和仿生蝠鲼机器鱼,并分析了SMA 丝的热力学特性,确定了控制规律．该机器鱼外形与双吻前口蝠鲼外形相似,身体呈现扁平形状,有一对三角形的柔性仿生胸鳍,直线游动速度达到79 mm/s,最小转弯半径为118 mm．该机器鱼游动稳定性好,无噪声．     

仿生“蚯蚓”机器人的SMA 执行器实现

虽然从生物学角度来说,蚯蚓的波浪式运动机制已经相当清楚,但在小尺寸下人工蚯蚓的实现仍然是极具挑战性的工作.采用记忆合金材料(SMA),设计实现了用于仿生蚯蚓机器人的执行器,并通过该执行器的动作循环模仿,实现了蚯蚓的波浪式运动.实现的人工蚯蚓共有四单元,每一单元都有可独立驱动的执行器.执行器由一根或三根SMA弹簧构成,其波动式运动的最高频率为0.6 Hz.每一单元人工蚯蚓,都被覆特定形状的软硅胶皮,该硅胶皮提供了SMA执行器的对抗力,同时也是安装微型腿的平台,从而进一步提高了人工蚯蚓的运动效率.初步的测试显示该执行器工作有效,人工蚯蚓的运动速度可达2.5mm/s,与真实的蚯蚓运动速度相近.     

Experimental comparison of classical PID and model-free control: Position control of a shape memory alloy active spring

Shape memory alloys (SMA) are being more frequently integrated into engineering applications. These materials with their shape memory effect enable the simplification of mechanisms and the reduction in size of actuators. SMA parts can easily be activated by Joule effect but their modeling and consequently their control remains difficult. It is principally due to their non-linear hysteretic thermomechanical behavior. Most of successful control strategies applied to SMA actuators are not often suitable for industrial applications: they are particularly heavy and use the Preisach model or neural networks to model the hysteretic behavior of these materials; this kind of model is difficult to identify and to use in real time. This paper deals with an application of the new framework of model-free control (MFC) of an SMA-spring based actuator. This control strategy relies on new results for fast derivative estimation of noisy signals. Their main advantages are: its simplicity and its robustness. Experimental results and comparisons with PI control are presented that demonstrate the efficiency of this new control strategy.     

形状记忆合金的驱动性能研究进展

简要介绍了SMA的物理与力学特性,并就其驱动性能的国内外研究现状进行了总结与分析.分析表明,利用SMA可以实时调控梁、板、柱等构件的应力分布,改变其受力状态.最后对目前研究中存在的问题进行了探讨,提出了应当开展的一些研究方向,展望了SMA在土木工程领域的应用前景.     

形状记忆合金驱动的微电脑密码锁的设计

为了提高锁的安全性和可靠性,设计了一种基于形状记忆合金螺旋弹簧驱动的微电脑密码锁。详细介绍了锁的机械结构、硬件设计方案和软件设计方法,并给出了部分电路图和程序主要流程图。本设计结合单片机的智能性和形状记忆合金材料的形状记忆效应,实现了密码锁封闭式的机械结构,提高了控制的智能化程度,克服了普通锁需要随身携带钥匙且易丢失、保密性差的缺点,使得密码锁的安全系数极高。实践证明,该密码锁具有可靠性高、成本低、操作简便等特点,有较高的推广价值。     

SMA驱动丝的建模与仿真

研究SMA动力学优化模型,针对形状记忆合金(SMA)驱动丝具有强非线性、迟滞效应等特性,为设计SMA驱动丝的自适应结构,提出建立SMA驱动丝模型并提供高效的仿真方法。采用有限元软件实现了受轴向载荷的SMA驱动丝的仿真建模。对本构模型是根据自由能的一维热-力学耦合模型,可以同时复现形状记忆效应和超弹性。数值仿真能够引起材料相变的非均匀温度和应变分布。仿真结果表明,建立热-力学耦合模型,可为设计SMA驱动丝的自适应结构计算提供可靠依据。     

Analysis,modeling and experimental validation of temperature-changing effect on mechanical properties of pneumatic artificial muscle

This paper focuses on quantify how temperature affects the mechanical properties of pneumatic artificial muscle (PAM). The influence of temperature variations on PAM’s structure size and internal friction was analyzed firstly, based on the thermal characteristics of rubber diaphragm and fiber mesh, then a novel model considering the influence of temperature variation is proposed, without any fitting parameter or any parameter with uncertain physical meanings. In order to verify the proposed model, temperature-rising experiments using heating device and continuous operation were both carried out separately. Through the comparison of characteristic curves under different temperatures, PAM’s characteristics were proven to be affected by temperature variations. The results show that inside temperature changing of PAM is why there are drifting and time-varying phenomenon of their mechanical characteristics in long-term operation, and the proposed model can predict the variations caused by temperature changing well. Meanwhile, the accuracy of the new model is higher than Chou model and lower than Andrikopoulos model; it is understandable because our new model has no fitting parameters, but the advantage of new model is that it takes temperature as independent variables and, therefore, can be used at different temperatures directly without any calibration.