This paper presents the design, control and evaluation of a novel robotic finger actuated by shape memory alloy (SMA) tubes which intrinsically afford an internal conduit for fluidic cooling. The SMA tubes are thermomechanically programmed to flex the robotic finger when Joule heated. A superelastic SMA plate provides a spring return motion to extend the finger when cooling liquid is pumped through the internal channel of the SMA tube actuators. The mechanical design and nonlinear force controller are presented for this unique robotic finger. Sinusoidal and step response experiments demonstrate excellent error minimization when operated below the bandwidth which was empirically determined to be 6 rad/s. Disturbance rejection experiments are also performed to demonstrate the potential to minimize externally applied forces. This method of internal liquid cooling of Joule heated SMA tubes simultaneously increases the system bandwidth and expands the potential uses of SMA actuators for robotic applications. The results show that this novel robotic finger is capable of precise force control and has a high strength to weight ratio. The finger can apply a force of 4.35 N and has a mass of 30 g. Implementing this design into wearable prosthetic devices could enable lightweight, high strength applications previously not achievable.

中文翻译：

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形状记忆合金管致动器本质上能够在力控制下对机器人手指进行内部流体冷却


本文介绍了一种由形状记忆合金（SMA）管驱动的新型机器人手指的设计、控制和评估，该管本质上提供了用于流体冷却的内部导管。 SMA 管经过热机械编程，可在焦耳加热时弯曲机器人手指。当冷却液被泵入 SMA 管致动器的内部通道时，超弹性 SMA 板提供弹簧复位运动以伸展手指。针对这种独特的机器人手指提出了机械设计和非线性力控制器。正弦曲线和阶跃响应实验表明，当在低于根据经验确定为 6 rad/s 的带宽运行时，可以实现出色的误差最小化。还进行了抗扰实验，以证明最小化外加力的潜力。这种焦耳加热 SMA 管的内部液体冷却方法同时增加了系统带宽，并扩展了 SMA 执行器在机器人应用中的潜在用途。结果表明，这种新型机器人手指能够精确控制力，并具有较高的强度重量比。手指可施加 4.35 N 的力，质量为 30 g。将这种设计应用到可穿戴假肢设备中可以实现以前无法实现的轻质、高强度的应用。