This paper presents our work on design, modeling and characterization of a novel shape memory alloy (SMA) actuated torsion actuator for meso-scale robots. Development of a miniature torsion actuator is challenging, but it can enhance the agility and enlarge the workspace of meso-scale robots. This torsion actuator comprises of a pair of antagonistic SMA torsion springs, which bi-directionally actuate the actuator by Joule heating and natural cooling. First, the mechanical design of the torsion actuator is presented, followed by the fabrication of SMA torsion springs. Then, we present the constitutive model of the SMA torsion spring with an analysis of its strain change, and derive a quasi-static model with the Coulomb friction torque for this torsion actuator. Finally, a series of characterization experiments are conducted on the SMA torsion spring and the torsion actuator prototype to determine the values of all model parameters. This work shows that the properties of the SMA-actuated torsion actuator can be appropriately characterized by experiments and the actuator is feasible for robotics applications.

中文翻译：

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一种新型中尺度 SMA 驱动扭力执行器的设计、建模和表征

本文介绍了我们在用于中尺度机器人的新型形状记忆合金 (SMA) 驱动扭力执行器的设计、建模和表征方面的工作。微型扭力执行器的开发具有挑战性，但它可以提高敏捷性并扩大中尺度机器人的工作空间。该扭力致动器由一对对抗性 SMA 扭力弹簧组成，通过焦耳加热和自然冷却双向致动致动器。首先，介绍了扭力执行器的机械设计，然后是 SMA 扭力弹簧的制造。然后，我们提出了 SMA 扭转弹簧的本构模型，并对其应变变化进行了分析，并推导出了该扭转执行器的库仑摩擦扭矩准静态模型。最后，对 SMA 扭转弹簧和扭转致动器原型进行了一系列表征实验，以确定所有模型参数的值。这项工作表明 SMA 驱动的扭转致动器的特性可以通过实验适当地表征，并且该致动器对于机器人应用是可行的。