Sitting posture has a close relationship with our health, and keeping a healthy sitting posture is critical to each of us. Poor sitting postures often inevitably increase the risk of modern health musculoskeletal disorders. Previous works either used a camera to record the image or attached wearable sensors on the human body to recognize sitting postures. However, video-based approaches may face privacy issues while the wearable sensor-based approaches may cause uncomfortable to the user. In this work, we propose SitR, the first sitting posture recognition system using RF signals alone, which neither compromises the privacy nor requires wearing various sensors on the human body. We demonstrate that SitR can successfully recognize seven habitual sitting postures with just three lightweight and low-cost RFID tags pasted to the user’s back. Our design exploits the correlation between the phase change of RFID tags and the sitting postures. By extracting effective features of the measured phase sequences and employing appropriate machine learning algorithm, SitR can achieve robust and high performance. We evaluate the performance of SitR with ten volunteers in two different scenarios. Extensive experiments show SitR can recognize seven sitting postures with a high accuracy across different scenarios and various conditions. SitR can further detect the abnormal respiration, stand up, and sit down and provide sitting posture history for sedentary people.

中文翻译：

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SitR：使用RF信号的坐姿识别

坐姿与我们的健康息息相关，保持健康的坐姿对我们每个人都至关重要。不良的坐姿常常不可避免地增加现代健康的肌肉骨骼疾病的风险。以前的作品要么使用照相机记录图像，要么使用可穿戴传感器安装在人体上以识别坐姿。但是，基于视频的方法可能会遇到隐私问题，而基于可穿戴传感器的方法可能会使用户感到不适。在这项工作中，我们提出了SitR，这是第一个仅使用RF信号的坐姿识别系统，既不会损害隐私，也不需要在人体上佩戴各种传感器。我们证明SitR只需将三个轻巧，低成本的RFID标签粘贴到用户的背部即可成功识别出七个惯用坐姿。我们的设计利用了RFID标签的相位变化与坐姿之间的相关性。通过提取被测相序的有效特征并采用适当的机器学习算法，SitR可以实现鲁棒和高性能。我们在两种不同的情况下与十名志愿者一起评估SitR的性能。大量实验表明，SitR可以在不同情况和各种条件下以很高的精度识别七个坐姿。SitR可以进一步检测异常呼吸，站立和坐下，并为久坐的人提供坐姿历史记录。SitR可以实现强大和高性能。我们在两种不同的情况下与十名志愿者一起评估SitR的性能。大量实验表明，SitR可以在不同情况和各种条件下以很高的精度识别七个坐姿。SitR可以进一步检测异常呼吸，站立和坐下，并为久坐的人提供坐姿历史记录。SitR可以实现强大和高性能。我们在两种不同的情况下与十名志愿者一起评估SitR的性能。大量实验表明，SitR可以在不同情况和各种条件下以很高的精度识别七个坐姿。SitR可以进一步检测异常呼吸，站立和坐下，并为久坐的人提供坐姿历史记录。