Department of Biomedical Sciences, Bioengineering Unit, University of Sassari, Sassari (SS), Italy; Interuniversity Centre of Bioengineering of the Human Neuromusculoskeletal System, Sassari (SS), Italy.
Department of Biomedical Sciences, Bioengineering Unit, University of Sassari, Sassari (SS), Italy; Interuniversity Centre of Bioengineering of the Human Neuromusculoskeletal System, Sassari (SS), Italy.
J Biomech. 2019 Feb 14;84:274-277. doi: 10.1016/j.jbiomech.2018.12.039. Epub 2018 Dec 31.
Accurate step detection is crucial for the estimation of gait spatio-temporal parameters. Although several step detection methods based on the use of inertial measurement units (IMUs) have been successfully proposed, they may not perform adequately when the foot is dragged while walking, when walking aids are used, or when walking at low speed. The aim of this study was to test an original step-detection method, the inter-foot distance step counter (IFOD), based on the direct measurement of the distance between feet. Gait data were recorded using a wearable prototype system (SWING), which integrates an IMU and two time-of-flight distance sensors (DSs). The system was attached to the medial side of the right foot with one DS positioned close to the forefoot (FORE) and the other close to the rearfoot (REAR). Sixteen healthy adults were asked to walk over ground for two minutes along a loop, including both rectilinear and curvilinear portions, during two experimental sessions. The accuracy of the IFOD step counter was assessed using a stereo-photogrammetric system as gold standard. The best performance was obtained for REAR with an accuracy higher than 99.8% for the instrumented foot step and 88.8% for the non-instrumented foot step during both rectilinear and curvilinear walks. Key features of the IFOD step counter are that it is possible to detect both right and left steps by instrumenting one foot only and that it does not rely on foot impact dynamics. The IFOD step counter can be combined with existing IMU-based methods for increasing step-detection accuracy.
准确的步伐检测对于步态时空参数的估计至关重要。尽管已经成功提出了几种基于惯性测量单元（IMU）使用的步伐检测方法，但当步行时脚被拖着、使用助行器或低速行走时，它们可能无法正常工作。本研究的目的是测试一种基于脚部直接距离测量的新型步伐检测方法——足间距离步伐计数器（IFOD）。步态数据使用可穿戴原型系统（SWING）进行记录，该系统集成了一个 IMU 和两个飞行时间距离传感器（DS）。系统通过一个 DS 安装在右脚的内侧，该 DS 靠近前脚（FORE），另一个靠近后脚（REAR）。在两个实验中，要求 16 名健康成年人在两分钟内沿着一个环路行走，包括直线和曲线部分。使用立体摄影测量系统作为金标准评估 IFOD 步伐计数器的准确性。REAR 的性能最佳，仪器化脚的准确率高于 99.8%，非仪器化脚的准确率高于 88.8%，无论是在直线还是曲线行走中。IFOD 步伐计数器的主要特点是仅通过仪器化一只脚就可以检测左右脚的步伐，并且不依赖于脚步冲击动力学。IFOD 步伐计数器可以与现有的基于 IMU 的方法相结合，以提高步伐检测的准确性。
