Browsing by Author "Wei, Yu-Lin"

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Augmenting Indoor Inertial Tracking with Polarized Light
(2018-01-01)
Tian, Zhao
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Wei, Yu-Lin
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Chang, Wei-Nin
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Xiong, Xi
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Zheng, Changxi
Inertial measurement unit (IMU) has long suffered from the problem of integration drift, where sensor noises accumulate quickly and cause fast-growing tracking errors. Existing methods for calibrating IMU tracking either require human in the loop, or need energy-consuming cameras, or suffer from coarse tracking granularity. We propose to augment indoor inertial tracking by reusing existing indoor luminaries to project a static light polarization pattern in the space. This pattern is imperceptible to human eyes and yet through a polarizer, it becomes detectable by a color sensor, and thus can serve as fine-grained optical landmarks that constrain and correct IMU's integration drift and boost tracking accuracy. Exploiting the birefringence optical property of transparent tapes - a low-cost and easily-accessible material - we realize the polarization pattern by simply adding to existing light cover a thin polarizer film with transparent tape stripes glued atop. When fusing with IMU sensor signals, the light pattern enables robust, accurate and low-power motion tracking. Meanwhile, our approach entails low deployment overhead by reusing existing lighting infrastructure without needing an active modulation unit. We build a prototype of our light cover and the sensing unit using off-the-shelf components. Experiments show 4.3 cm median error for 2D tracking and 10 cm for 3D tracking, as well as its robustness in diverse settings.
CELLI - Indoor Positioning using Polarized Sweeping Light Beams
(2017-01-01)
Wei, Yu-Lin
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Huang, Chang-Jung
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Tsai, Hsin-Mu
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Lin, Kate Ching-Ju
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資訊工程學系
CELLI: Indoor Positioning Using Polarized Sweeping Light Beams
(2017-01-01)
Wei, Yu-Lin
;
Huang, Chang-Jung
;
Tsai, Hsin-Mu
;
Lin, Kate Ching-Ju
;
資訊工程學系
Existing visible light positioning (VLP) systems leverage the high image resolution of a receiving camera to support high positioning accuracy. However, power-hungry cameras might not always be applicable for many scenarios, such as smart factories, in which small objects require to be accurately localized and tracked. In this paper, we introduce CELLI, an indoor VLP system that only uses a single luminary as the transmitter and requires only a simple light sensor to achieve an extremely high accuracy with centimeter-level error. The key idea is to provide the spatial resolution capability from the transmitter instead of the receiver, so that the complexity of the receiver can be minimized. In particular, a small LCD is installed at the transmitter to project a large number of narrow and interference-free polarized light beams to different spatial cells. A receiving light sensor identifies its located cell by detecting the unique polarization-modulated signals projected to that cell. CELLI further incorporates a number of novel designs to overcome the technical challenges such as reducing the positioning latency, which is typically limited by the long optical response time of an LCD, and transforming a cell coordinate to the global 3D position using only a single light. We have prototyped our design using off-the-shelf optical and electrical components, and experimentally shown that CELLI achieves a median 3D positioning error less than 11.8 cm and a median 2D positioning error to less than 2.7 cm.
Design of ESD Protection Cell for Dual-Band RF Applications in a 65-nm CMOS Process
(2012)
Chu, Li-Wei
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Lin, Chun-Yu
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Tsai, Shiang-Yu
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Ker, Ming-Dou
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Song, Ming-Hsiang
An ESD protection cell consisted of a diode, a silicon-controlled rectifier (SCR), a PMOS, and inductors was proposed for dual-band radio-frequency (RF) ESD protection. The proposed ESD protection cell was suitable for RF circuit designers for them to easily apply ESD protection in the dual-band RF circuits.
ESD Protection Design for Radio-Frequency Integrated Circuits in Nanoscale CMOS Technology
(2013-01-01)
Lin, Chun-Yu
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Chu, Li-Wei
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Tsai, Shiang-Yu
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Ker, Ming-Dou
;
Song, Ming-Hsiang
Nanoscale CMOS technologies have been used to implement the radio-frequency integrated circuits. However, the thinner gate oxide in nanoscale CMOS technology seriously degrades the electrostatic discharge (ESD) robustness of IC products. Therefore, on-chip ESD protection designs must be added at all input/output pads in CMOS chip. To minimize the impacts from ESD protection on circuit performances, ESD protection at input/output pads must be carefully designed. In this work, a new proposed ESD protection design has been realized in a nanoscale CMOS process. Experimental results of the test circuits have been successfully verified, including RF performances, I-V characteristics, and ESD robustness.
LiCompass: Extracting Orientation from Polarized Light
(2017-01-01)
Wei, Yu-Lin
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Wu, Hsin-I
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Wang, Han-Chung
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Tsai, Hsin-Mu
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Lin, Kate Ching-Ju
Accurate orientation information is the key in many applications, ranging from map reconstruction with crowdsourcing data, location data analytics, to accurate indoor localization. Many existing solutions rely on noisy magnetic and inertial sensor data, leading to limited accuracy, while others leverage multiple, dense anchor points to improve the accuracy, requiring significant deployment efforts. This paper presents LiCompass, the first system that enables a commodity camera to accurately estimate the object orientation using just a single optical anchor. Our key idea is to allow a camera to observe varying intensity level of polarized light when it is in different orientations and, hence, perform estimation directly from image pixel intensity. As the estimation relies only on pixel intensity, instead of the location of the anchor in an image, the system performs reliably at long distance, with low resolution images, and with large perspective distortion. LiCompass' core designs include an elaborate optical anchor design and a series of signal processing techniques based on trigonometric properties, which extend the range of orientation estimation to full 360 degrees. Our prototype evaluation shows that LiCompass produces very accurate estimates with median errors of merely 2.5 degrees at 5 meters and 7.4 degrees at 2.5 meters with an irradiance angle of 55 degrees.
Location-Independent WiFi Action Recognition via Vision-based Methods
(2016)
Chang, Jen-Yin
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Lee, Kuan-Ying
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Wei, Yu-Lin
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Lin, Kate Ching-Ju
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Hsu, Winston
Due to die characteristics of ubiquity, non occlusion,privacy preservation of Win, many researchers have devoted to human action recognition using WiFi signals. As demonstrated in [1], Channel State information (CSI), a fine-grained information capturing the properties of WiFi signal propagation, could be transformed into images for achieving a promising accuracy on action recognition via vision-based :methods. However, from the experimental results shown in [1], the CSI is usually location dependent, which affects the recognition performance if signals are recorded in different places. In this paper. We propose a location-dependency removal method based on Singular Value Decomposition (SVD) to eliminate the background CSI and effectively extract the channel information of signals reflected by human bodies. Experimental results show that our method considering the correlation of CST streams could achieve promising accuracy above 90% in identifying six actions even testing in live different rooms.