| Innovative Design |
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| Design of new shape memory alloy actuator and three-fingered dexterous hand |
| LI Da-hong, JIN Ying-zi, GUO Zhen-wu, WANG Bin-rui |
| College of Mechanical and Electrical Engineering, China Jiliang University, Hangzhou 310018, China |
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Abstract Aiming at the problem that the shape memory alloy (SMA) temperature feedback control is difficult to achieve and the small SMA dependent variable leads to small drive displacement in practical applications, a new SMA actuator based on resistance feedback control was designed. A three-fingered dexterous hand with rope transmission was developed using this actuator. The new SMA actuator was consist of a pulley, a hollow stud, SMA wire and spring drawing device.The using length of the SMA wire was developed by using a pulley winding to increase the drive displacement output. A switch control system based on resistance feedback was designed based on the relationship between the change of SMA resistance and phase which was obtained by the resistance characteristics of SMA itself. The three-fingered dexterous hand was designed with modular idea, having 8 degrees of freedom for 3 fingers, and its ability to grab objects was verified through the experiment. The result showed that the new actuator did not need to judge the SMA wire phase change process by measuring temperature, and eliminated the external temperature sensor.The output of actuator could reach more than 8% of the total drive length. Monitoring the resistance change of the SMA wire could realize the control of the electric heating of the actuator and prevent the SMA wire from being overheated and burned.The results provide an idea for increasing the drive displacement and reducing the control difficulty of SMA actuator.
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Received: 14 March 2019
Published: 28 October 2019
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新型形状记忆合金驱动器与三指灵巧手设计
针对现有形状记忆合金（shape memory alloy，SMA）温度反馈控制难以实现及SMA应变量小导致实际应用中存在驱动位移小的问题，提出了一种基于电阻反馈控制的新型SMA驱动器，并采用这种驱动器研发了一种绳索传动的三指灵巧手。新型SMA驱动器由滑轮、空心螺柱、SMA丝和弹簧拉伸装置等组成，通过采用滑轮绕线的方式增长SMA丝的使用长度以提高驱动位移输出量；利用SMA自身的电阻特性得到SMA电阻变化与相变的关系，设计了基于电阻反馈的开关控制系统；采用模块化思想设计了三指灵巧手，3根手指共有8个自由度，并通过实验验证三指灵巧手对物品的抓取能力。结果表明：新型SMA驱动器不需要通过测温来判断SMA丝相变进程，省去了外部温度传感器；SMA驱动器输出的驱动量可达驱动器总长的8%以上；通过监测SMA丝的电阻变化可实现驱动器通电加热的控制，防止SMA丝过热烧毁。研究结果为提高SMA驱动器驱动位移和降低SMA驱动器控制难度提供了一种思路。
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