- The paper demonstrates a novel tenodesis-modulated control approach that significantly enhances grasp performance for individuals with SCI.
- It details the MyHand-SCI design, which uses underactuation via exotendons and Bowden cables to preserve natural wrist mobility.
- Participant testing on the Grasp and Release Test showed marked improvements, supporting further development of adaptive control features.
Introduction to Hand Exoskeletons for SCI
Spinal Cord Injuries (SCI) profoundly affect individuals' lives, often impairing motor functions such as hand movement which is crucial for independence. Restoring hand function is thus a high-priority goal for people with SCI. Remarkably, individuals with certain levels of SCI retain wrist mobility and utilize a method called tenodesis for basic grasping, although this method often cannot provide the necessary force to perform daily activities. This underscores the need for supportive technology, particularly devices that can assist in more robust grasping while allowing users to maintain their wrist movement for control.
MyHand-SCI: Design Philosophy
The MyHand-SCI is an innovative assistive device designed with the comfort and needs of individuals with C6-C7 SCI in mind. Its design aims to assist with pinch and power grasps, crucial for everyday actions. The device is underactuated, meaning a single motor can control multiple fingers to produce a synergistic grasping motion while also being lightweight as not to burden the user. Key to this design is the preservation of wrist mobility, which is essential for enabling a natural tenodesis-like grasp. MyHand-SCI achieves this with a smart configuration of exotendons and Bowden cables to mimic anatomical structures of the hand, thereby allowing free wrist motion alongside assisted finger flexion.
Participant Testing and Results
The performance of the MyHand-SCI device was evaluated through tests with a participant who had C6 tetraplegia. The Grasp and Release Test (GRT), which measures the ability to manipulate objects of different weights and sizes, was used for this assessment. With the aid of the device, the participant’s score improved significantly. Controlled by a researcher in response to the participant’s verbal cues, the device demonstrated its capacity for modulation of grasping force, which proved beneficial and warrants further exploration. Importantly, the participant maintained both comfort and unimpeded wrist movement during the testing session.
Future Directions
Encouraged by these preliminary but promising results, future work will focus on integrating tenodesis-modulated control, allowing users to intuitively command the device by extending their wrist. The system might eventually incorporate wrist extension data to tailor finger movement and grasping force dynamically. Additionally, a grasp-locking feature could be added to further reduce user effort and enhance functionality. Before deploying the device to more people with SCI, it will undergo testing with healthy individuals to ensure safety and to fine-tune the intuitiveness of the control mechanisms. This developmental path suggests a bright future for assistive technologies that are both effective in aiding people with SCI and ergonomic in their design.