October 12, 2015Robotic finger mimics human digits as it is heated and cooled

The team says the robotic finger could help to overcome some of the challenges encountered by researchers working in the ocean depths (Credit: Florida Atlantic University)

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Scientists at Florida Atlantic University have employed a novel thermal training technique to give robotic fingers a natural look and feel. With the ability to curve and straighten as it is heated and cooled, the researchers are hopeful their lifelike new creation will be put to use in underwater robotics and eventually, advanced prosthetic devices.

The researchers began with a 3D CAD model of a human finger. From this, they created a model of the digit and then 3D printed inner and outer molds, between which they placed a flexor and extensor actuator made from shape memory allow (SMA), along with a position sensor.

The flexor actuator was trained to take the shape of a bent human finger when heated, while the extensor was trained to straighten out when heated. So by alternately heating and cooling the two actuators, the finger in could be made to bend and straighten. This was done through a process called Joule heating, which sees electrical currents pass through a heat-generating conductor.

One problem the researchers encountered was the time it takes for each actuator to cool again and resume its natural shape after being heated. Because of this, they are looking to undersea robotics as the finger's first port of call. In an underwater environment, thermal insulators fitted to the tip of the finger can allow water to flow throughout the cavity and more efficiently cool the actuators, which the researchers say greatly improves the operational speed of the device.

Eventually it is hoped that the approach can be used fin the development of better prostheses.

"We have been able to thermomechanically train our robotic finger to mimic the motions of a human finger like flexion and extension," says Erik Engeberg, assistant professor at FAU. "Because of its light weight, dexterity and strength, our robotic design offers tremendous advantages over traditional mechanisms, and could ultimately be adapted for use as a prosthetic device, such as on a prosthetic hand."

The research was published in the journal Bioinspiration & Biomimetics.

机械手指能够模仿人类手指受热和手冷时的情形

Robotic手指模仿人类的??数字，因为它被加热和cooled

该小组说，机器人的手指可以帮助克服一些研究人员在海洋深处工作所遇到的挑战（图片来源：佛罗里达大西洋大学）

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科学家在佛罗里达大西洋大学已经采用了一种新的热训练技术给机器人的手指一个自然的外观和感觉。随着和拉直，因为它被加热和冷却能力曲线，研究人员希望他们的栩栩如生的新的创造将投放水下机器人，最终，先进的假肢装置使用。

研究人员开始了与人类的三维CAD模型手指。从这一点，他们创建的数字的一个模型，然后三维印刷内和外模，在它们之间它们置于一个屈肌和伸肌激励器由形状记忆制成允许（SMA），还有一个位置传感器。

屈致动器被训练采取弯曲的人的手指的形状，当加热，而伸肌被训练理顺加热时。因此，通过交替地加热和冷却所述两个致动器，所述手指可以作出弯曲和伸直。这是通过一个称为焦耳加热过程，看到的电流通过发热导体完成。研究者遇到

一个问题是它需要对每个致动器，以再次冷却，加热后恢复其自然形状的时间。正因为如此，他们正在寻找国际海底机器人呼叫的手指的第一个端口。在水下环境中，热绝缘体装配到指尖可以允许水流在整个腔和更有效地冷却所述致动器，其中，研究人员表示极大地提高了装置的运行速度。

最终，它希望该方法可用于散热片更好的假体的发展。

“我们已经能够热机械训练我们的机器人手指模仿人类手指的动作就像屈伸，”埃里克Engeberg说，副教授FAU。 “由于其重量轻，灵巧和力量，我们的机器人设计提供了极大的优势，比传统的机制，最终可能适于用作假肢装置，如一个假手。”

这项研究发表在杂志Bioinspiration和放大器; 。仿生学