Development of a new generation prosthetic hand with fast responsive SMA based artificial muscle and large load-holding capability

形状记忆合金（SMA）丝目前是柔软人工肌肉的首选。然而，SMA人造肌肉有两个问题，包括由于其柔软的性质而导致的有限的负荷保持能力和由于其长的冷却期而导致的缓慢的响应。为此，本研究开发了一种基于形状记忆合金的快速响应磁流变弹性体（MRE）人工肌肉和一种可控磁流变液（MRF）外骨骼，以提高其承载能力。这种新的人造肌肉保留了其柔软的性质，同时也加快了其SMA线的冷却速度，以提高其响应速度。可控的MRF外骨骼足够灵活，以允许柔软的手指根据需要弯曲，同时足够坚硬以支撑重负载。从今年年初开始，我已经为新的人工肌肉建立了控制电路和程序，之后，新的人工肌肉和MR外骨骼已经组装成一根手指，以进行进一步的测试。对手指的弯曲性能进行了测试。对手指的最大弯曲角度和响应速度进行了评价。新的假肢手指的持有能力也进行了评估。测试结果表明，与传统的SMA人工肌肉相比，这种新型人工肌肉在矫直时的响应速度可提高333%。新的人工肌肉和MRF外骨骼组装了一个机器人手指，我们的测试验证了新手指的负载能力比纯SMA机械手增加了440%。

Shape memory alloy (SMA) wires are now the preferred choice for soft artificial muscles. However, SMA artificial muscles have two problems, including limited load holding ability due to their soft nature and slow response due to their long cooling-off period. In response this research developed a fast response magnetorheological elastomer (MRE) artificial muscle based on SMA and a controllable magnetorheological fluid (MRF) exoskeleton to improve the loading capability. This new artificial muscle retains its soft nature and also accelerates the cooling speed of its SMA wire to increase its response speed. The controllable MRF exoskeleton is flexible enough to allow the soft fingers to bend as required while being stiff enough to hold up heavy loads. From the beginning of this year, I have built a control circuit and program for the new artificial muscle and after that, the new artificial muscle and MR exoskeleton have been assembled to be a finger for further testing. The bending performance of the finger has been conducted. The maximum bending angle and the response speed of the finger have been evaluated. The holding capability of the new prosthetic finger has also been evaluated. Our testing results proved that this new artificial muscle, compared with conventional SMA artificial muscles, can improve the response speed by up to 333% while straightening. The new artificial muscle and the MRF exoskeleton assembled a robotic finger and our tests verified that the loading capability of the new finger has increased by 440% compared to the pure SMA manipulator.