Background and objective

Equipments generally used for entertainment, such as Microsoft Kinect, have been widely used for postural control as well. Such systems—compared to professional motion tracking systems—allow to obtain non-invasive and low-cost tracking. This makes them particularly suitable for the implementation of home rehabilitation systems. Microsoft has recently released a new version of Kinect, namely Azure Kinect DK, that is meant for developers, not consumers, and it has been specifically designed to implement professional applications. The hardware of this new version of the Kinect has been substantially improved as compared with previous versions. However, the accuracy of the Azure Kinect DK has not been evaluated yet in the context of the assessment of postural control as done for its predecessors.

Methods

We present a study to compare the motion traces of the Azure Kinect DK with those of a Vicon 3D system, typically considered the gold standard for high-accuracy motion tracking. The study involved 26 subjects performing specific functional reach and functional balance exercises.

Results

The results clearly indicates that the Azure Kinect DK provides a very accurate tracking of the main joints of the body for all the recording taken during the lateral reach movement. The Root Mean Square Error (RMSE) between the two tracking systems obtained is approximately 0.2 for the lateral and forward exercises while for the balance exercise it is around 0.47 considering the average of the results among all the joints. The angular Mean Absolute Error is approximately in the range 5–15 degrees for all the upper joints and independently on the exercise. The lower body joints show a higher angular error between the two systems. Not surprisingly, it was found that results are much better in correspondence of slow movements.

Conclusions

The results achieved that the Azure Kinect DK has an incredibly high potential to be used in applications of home rehabilitation, where the assessment of postural control is a fundamental and crucial activity.

中文翻译：

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通过 Microsoft Azure Kinect DK 进行姿势控制评估：一项评估研究

背景和目的

通常用于娱乐的设备，例如 Microsoft Kinect，也已广泛用于姿势控制。与专业运动跟踪系统相比，此类系统允许获得非侵入性和低成本的跟踪。这使得它们特别适用于家庭康复系统的实施。微软最近发布了一个新版本的 Kinect，即 Azure Kinect DK，它是为开发者而不是消费者设计的，它是专门为实现专业应用程序而设计的。与之前的版本相比，这个新版本 Kinect 的硬件有了很大的改进。然而，Azure Kinect DK 的准确性尚未在姿势控制评估的背景下进行评估，就像对其前辈所做的那样。

方法

我们提出了一项研究，将 Azure Kinect DK 的运动轨迹与 Vicon 3D 系统的运动轨迹进行比较，后者通常被认为是高精度运动跟踪的黄金标准。该研究涉及 26 名受试者进行特定的功能伸展和功能平衡练习。

结果

结果清楚地表明，Azure Kinect DK 为横向伸展运动期间拍摄的所有记录提供了对身体主要关节的非常准确的跟踪。获得的两个跟踪系统之间的均方根误差（RMSE）对于横向和前向练习约为 0.2，而对于平衡练习，考虑到所有关节之间的结果的平均值，它约为 0.47。所有上关节的角度平均绝对误差大约在 5-15 度的范围内，并且与锻炼无关。下半身关节在两个系统之间显示出更高的角度误差。毫不奇怪，发现与缓慢运动对应的结果要好得多。

结论

结果表明，Azure Kinect DK 具有令人难以置信的巨大潜力，可用于家庭康复应用，其中姿势控制的评估是一项基本且至关重要的活动。