Markovic Marko, Karnal Hemanth, Graimann Bernhard, Farina Dario, Dosen Strahinja
Institute of Neurorehabilitation Systems, Clinics for Trauma, Orthopedic and Plastic Surgery, University Medical Center Göttingen, Georg-August University, 37075 Göttingen, Germany.
J Neural Eng. 2017 Jun;14(3):036007. doi: 10.1088/1741-2552/aa620a. Epub 2017 Mar 29.
Providing sensory feedback to the user of the prosthesis is an important challenge. The common approach is to use tactile stimulation, which is easy to implement but requires training and has limited information bandwidth. In this study, we propose an alternative approach based on augmented reality.
We have developed the GLIMPSE, a Google Glass application which connects to the prosthesis via a Bluetooth interface and renders the prosthesis states (EMG signals, aperture, force and contact) using augmented reality (see-through display) and sound (bone conduction transducer). The interface was tested in healthy subjects that used the prosthesis with (FB group) and without (NFB group) feedback during a modified clothespins test that allowed us to vary the difficulty of the task. The outcome measures were the number of unsuccessful trials, the time to accomplish the task, and the subjective ratings of the relevance of the feedback.
There was no difference in performance between FB and NFB groups in the case of a simple task (basic, same-color clothespins test), but the feedback significantly improved the performance in a more complex task (pins of different resistances). Importantly, the GLIMPSE feedback did not increase the time to accomplish the task. Therefore, the supplemental feedback might be useful in the tasks which are more demanding, and thereby less likely to benefit from learning and feedforward control. The subjects integrated the supplemental feedback with the intrinsic sources (vision and muscle proprioception), developing their own idiosyncratic strategies to accomplish the task.
The present study demonstrates a novel self-contained, ready-to-deploy, wearable feedback interface. The interface was successfully tested and was proven to be feasible and functionally beneficial. The GLIMPSE can be used as a practical solution but also as a general and flexible instrument to investigate closed-loop prosthesis control.
为假肢使用者提供感觉反馈是一项重大挑战。常见方法是使用触觉刺激，这种方法易于实施，但需要训练且信息带宽有限。在本研究中，我们提出一种基于增强现实的替代方法。
我们开发了GLIMPSE，这是一款谷歌眼镜应用程序，它通过蓝牙接口连接到假肢，并使用增强现实（透视显示）和声音（骨传导换能器）呈现假肢状态（肌电信号、开口度、力和接触情况）。在一项改良的夹衣夹测试中，该接口在健康受试者中进行了测试，受试者在使用假肢时分为有反馈组（FB组）和无反馈组（NFB组），该测试允许我们改变任务难度。结果指标包括未成功试验的次数、完成任务的时间以及对反馈相关性的主观评分。
在简单任务（基本的、同色夹衣夹测试）中，FB组和NFB组的表现没有差异，但在更复杂的任务（不同阻力的夹子）中，反馈显著提高了表现。重要的是，GLIMPSE反馈并未增加完成任务的时间。因此，补充反馈可能在要求更高的任务中有用，从而不太可能从学习和前馈控制中受益。受试者将补充反馈与内在信息源（视觉和肌肉本体感觉）相结合，制定了自己独特的策略来完成任务。
本研究展示了一种新颖的、自成一体的、可随时部署的可穿戴反馈接口。该接口已成功测试，并被证明是可行的且具有功能优势。GLIMPSE既可以用作实际解决方案，也可以用作研究闭环假肢控制的通用且灵活的工具。
