Gyro in the air: tracking 3D orientation of batteryless internet-of-things
Gyro in the air: tracking 3D orientation of batteryless internet-of-things
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DOI：
10.1145/2973750.2973761
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发表时间：
2016-10
期刊：
影响因子：
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通讯作者：
Teng Wei;Xinyu Zhang
中科院分区：
文献类型：
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作者：
Teng Wei;Xinyu Zhang
3D 方向跟踪是许多物联网应用的重要组成部分。然而，现有的方向跟踪系统通常需要仅在电池供电的设备上可用的运动传感器。在本文中，我们提出了 Tagyro，它将一系列无源 RFID 标签作为方向传感器附加在日常物体上。 Tagyro 使用封闭式模型将标签之间的运行时相位偏移转换为方向角。为了实现 3D 空间中的方向跟踪，我们发现关键的挑战在于实际标签的不完美辐射模式，这是由天线极性、非各向同性发射和电磁耦合引起的，这会严重扭曲相位测量。我们通过设计一套相位采样和恢复算法来应对这些挑战，这些算法共同实现了具有 3 个自由度的可靠方向感测。我们在商品 RFID 系统上实施了实时版本的 Tagyro。我们的实验表明，Tagyro 可以以每秒 37.7 个样本的处理速率跟踪被动物体的 3D 方向，误差仅为 4°。
3D orientation tracking is an essential ingredient for many Internet-of-Things applications. Yet existing orientation tracking systems commonly require motion sensors that are only available on battery-powered devices. In this paper, we propose Tagyro, which attaches an array of passive RFID tags as orientation sensors on everyday objects. Tagyro uses a closed-form model to transform the run-time phase offsets between tags into orientation angle. To enable orientation tracking in 3D space, we found the key challenge lies in the imperfect radiation pattern of practical tags, caused by the antenna polarity, non-isotropic emission and electromagnetic coupling, which substantially distort phase measurement. We address these challenges by designing a set of phase sampling and recovery algorithms, which together enable reliable orientation sensing with 3 degrees of freedom. We have implemented a real-time version of Tagyro on a commodity RFID system. Our experiments show that Tagyro can track the 3D orientation of passive objects with a small error of 4°, at a processing rate of 37.7 samples per second.