A team of researchers from the University of Science and Technology of China (USTC) has recently developed a lightweight prosthetic hand with 19 degrees of freedom (DOF), capable of replicating human hand functions. This development can assist in the functional rehabilitation and daily activities of millions of upper-limb amputees. The research was published in Nature Communications .
The human hand, with its 23 degrees of freedom, accounts for about 54% of the body's total movement ability, despite weighing only around 1/150 of the body weight. However, traditional prosthetic hands usually rely on motor-driven mechanisms, which often face limitations due to low power density, resulting in difficulties balancing between DOF and weight. Therefore, designing more effective prosthetic hands requires addressing both high DOF dexterous movement and user comfort.
To address the challenge, the research team utilized shape-memory alloys (SMA) with high power-to-weight ratios as artificial muscle actuators. They employed a biomimetic tendon-driven transmission system that amplifies the driving force of the SMA while reducing transmission resistance. Based on the characteristics of tendon-like separate transmissions, the researchers integrated 23 sensor units into the fingers and wrist to achieve precise joint control.
Additionally, the prosthetic hand includes a cooling module with 38 SMA actuators, enabling 19 active DOF. Thanks to this biomimetic design and high integration, the prosthetic hand weighs only 0.37 kg and possesses human-level dexterity, capable of performing daily tasks such as combing hair, writing, shaking hands, exchanging business cards, and playing chess.
As for functionality, the prosthetic hand integrates voice recognition technology, providing a simple, user-friendly, and cost-effective human-machine interaction system. It supports 60 languages and 20 dialects, with a recognition accuracy rate of 95% and a response time measured in milliseconds, making it suitable for widespread use among amputees. Apart from that, the hand also demonstrates the ability to operate scissors, use a smartphone, and perform complex sign language gestures. It replicated 33 traditional human hand grasping motions and added six more advanced grasping actions, offering a broad range of application scenarios.
In summary, this research represents a leap forward in the field of prosthetics. The new technology has the potential to change the lives of amputees by giving them the ability to move more freely, perform daily tasks with greater ease, and regain their confidence. Furthermore, the hand shows great potential for engineering applications, providing an effective solution for both humanoid robot dexterity and high-performance prosthetic hand research.
