Scott Bradley, McInnes Mhairi, Chadwick Edward K, Blana Dimitra
School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK.
School of Engineering, University of Aberdeen, Aberdeen, UK.
Int Biomech. 2025 Dec;12(1):1-13. doi: 10.1080/23335432.2025.2556187. Epub 2025 Sep 5.
This study evaluates the accuracy of single camera markerless motion capture (SCMoCap) using Microsoft's Azure Kinect, enhanced with inverse kinematics (IK) via OpenSim, for upper limb movement analysis. Twelve healthy adults performed ten upper-limb tasks, recorded simultaneously by OptiTrack (marker-based) and Azure Kinect (markerless) from frontal and sagittal views. Joint angles were calculated using two methods: (1) direct kinematics based on body coordinate frames and (2) inverse kinematics using OpenSim's IK tool with anatomical keypoints. Accuracy was evaluated using root mean square error (RMSE) and Bland-Altman analysis. Results indicated that the IK method slightly improved joint angle agreement with OptiTrack for simpler movements, with an average RMSE of 8° for shoulder elevation in the sagittal plane compared to 9° with the coordinate frame method. However, both methods had higher RMSEs for rotational measurements, with IK and coordinate frame methods at 21° for shoulder rotation in the sagittal plane. Forearm pronation-supination measurements were unreliable due to tracking limitations. These findings suggest that Kinect with IK improves accuracy for simpler movements but struggles with rotational joint mechanics. Future research should focus on enhancing markerless tracking algorithms to fully realise the benefits of IK.
本研究评估了使用微软Azure Kinect的单摄像头无标记运动捕捉（SCMoCap）的准确性，该技术通过OpenSim的逆运动学（IK）进行增强，用于上肢运动分析。12名健康成年人执行了10项上肢任务，由OptiTrack（基于标记）和Azure Kinect（无标记）从正面和矢状面同时记录。使用两种方法计算关节角度：（1）基于身体坐标系的直接运动学；（2）使用OpenSim的IK工具和解剖学关键点的逆运动学。使用均方根误差（RMSE）和Bland-Altman分析评估准确性。结果表明，对于较简单的运动，IK方法与OptiTrack的关节角度一致性略有改善，矢状面肩部抬高的平均RMSE为8°，而坐标系方法为9°。然而，两种方法在旋转测量方面的RMSE都较高，矢状面肩部旋转时IK和坐标系方法均为21°。由于跟踪限制，前臂旋前-旋后测量不可靠。这些发现表明，带有IK的Kinect提高了较简单运动的准确性，但在旋转关节力学方面存在困难。未来的研究应专注于增强无标记跟踪算法，以充分实现IK的优势。
