Wireless networks: Mobile devices keep track

Nov. 21, 2012 — A more sensitive technique for determining user position could lead to improved location-based mobile services.

Many mobile-phone applications (apps) use spatial positioning technology to present their user with location-specific information such as directions to nearby amenities. By simultaneously predicting the location of the mobile-user and the data access points, or hotspots, improved accuracy of positioning is now available, thanks to an international research team including Sinno Jialin Pan from the A*STAR Institute for Infocomm Research1. Software developers expect that such improvements will enable a whole new class of apps that can react to small changes in position.

Traditionally, device position was determined by the Global Positioning System (GPS) that uses satellites to triangulate approximate location, but its accuracy falters when the mobile device is indoors. An alternative approach is to use the 'received signal strength' (RSS) from local transmitters. Attenuation of radio waves by walls can limit accuracy; and, it is difficult to predict signals in complex, obstacle-filled environments.

Software developers have tried to circumvent these problems by using so-called 'learning-based techniques' that identify correlations between RSS values and access-point placement. Such systems do not necessarily require prior knowledge of the hotspot locations; rather they 'learn' from data collected on a mobile device. This also has drawbacks: the amount of data can be large, making calibration time consuming. Changes in the environment can also outdate the calibration.

Pan and his co-workers reduced this calibration effort in an experimental demonstration of a protocol that calculates both the positions of the device and the access points simultaneously -- a process they call colocalization. "Integrating the two location-estimation tasks into a unified mathematical model means that we can fully exploit the correlations between mobile-device and hotspot position," explains Pan.

First, the researchers trained a learning-based system with the signal-strength values received from access points at selected places in the area of interest. They used this information to calibrate a probabilistic 'location-estimation' system. Then, they approximated the location from the learned model using signal strength samples received in real-time from the access points.

Experimental trials showed that this approach not only required less calibration, but it was more accurate than other state-of-the-art systems. "We next want to apply the method to a larger-scale environment," says Pan. "We also want to find ways to make use of the estimated locations to provide more useful information, such as location-based advertising." As this technique could help robots navigate by themselves, it may also have important implications for the burgeoning field of robotics.

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The above story is reprinted from materials provided by The Agency for Science, Technology and Research (A*STAR).

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Journal Reference:

Jeffrey Junfeng Pan, Sinno Jialin Pan, Jie Yin, Lionel M. Ni, Qiang Yang. Tracking Mobile Users in Wireless Networks via Semi-Supervised Colocalization. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2012; 34 (3): 587 DOI: 10.1109/TPAMI.2011.165

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Glove keyboard may revolutionize use of devices with one hand

Oct. 23, 2012 — Give a hand to some computer engineering students at The University of Alabama in Huntsville for designing a tool that could revolutionize new ways of using electronic devices with just one hand.

It's called a Gauntlet Keyboard, a glove device that functions as a wireless keyboard. Instead of tapping keys on a keyboard, the user simply touches their thumb to points on their fingers assigned a letter or other keyboard function.

Conductive thread carries the commands to a matchbox-sized Printed Circuit Board (PCB) affixed to the back of the glove.

The PCB transmits it via Bluetooth, whether it's a computer, a mobile phone, music synthesizer, video game or military device. Think of the Gauntlet as a touch screen that works by tapping your fingers to your thumb on a gloved hand.

Four senior engineering students at UAH made the glove their senior design project for a computer engineering class led by Dr. B. Earl Wells.

The students -- Jiake Liu, Stephen Dond, Douglas Kirby and Chris Heath -- are now seeking a patent to market the product. The project recently won a $20,000 prize from the Best Buy Innovator Fund among hundreds of entries.

"It's basically a keyboard on your hand," explained Lui, the principal innovator. "You, by tapping your thumb on each segment of your fingers, type to the screen basically. And you can do a swiping gesture that would erase it."

Gauntlet is an acronym for Generally Accessible Universal Nomadic Tactile Low-power Electronic Typist. That's a lengthy description of what essentially is a glove with a beehive of conductive threads running throughout the fingers and palm.

Liu said the inspiration came from his interest in science fiction movies and experience with touch-screen technologies.

Once he and his project partners came up with the idea, they did some scientific research on the most frequently used characters on a keyboard. Common keystrokes got the easiest finger-thumb alignments like the fingertips. Less common ones required more hand contortions to make the contacts.

"Doug (Kirby) did some research and found the most commonly used letters in the English alphabet," said Dond. "We all sat around and asked a few people and tried to figure these easiest places to touch your finger with your thumb and we put the most commonly used letters there. We tried to make it as efficient and easy to use as possible."

Until users memorize the new "key" positions, the characters are sewn into the finger and palm positions of the glove. Liu said the group has been in contact with a patent lawyer and a specialty glove designer about going commercial with the Gauntlet.

The students were assisted in their initial work by Huntsville electronics firm ADTRAN after entering it in the company's senior design showcase. The company assisted largely with the micro soldering of the PCB parts.

The young designers are excited about the possibilities for the Gauntlet. "There are several applications we can think of right now," Liu said. "The easy one would be as a keyboard for the consumer market. Also, the medical field for people limited to one hand from a disability. We can also think of military uses, as an entertainment device or used as a musical instrument for digital synthesizing."

Dr. Emil Jovanov, associate dean for Graduate Education and Research in the UAH College of Engineering, commended the students for their innovation. "It is a perfect example of how you take an original idea, find your niche and complete the whole idea."

Jovanov said the project would be pitched to the Alabama Launch Pad, a competition to help fund and launch business plans.

The young innovators are well on their way to success with their UAH education. Liu is co-founder and chief executive officer of Kabob, a smart phone application that provides users with digital versions of restaurant menus. Heath and Dond landed engineering jobs at Teledyne Brown, while Kirby got hired as a software engineer for Aegis Technologies.

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The above story is reprinted from materials provided by University of Alabama Huntsville.

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Scientists discover ways to optimize light sources for vision: Tuning lighting devices could save billions

Nov. 15, 2012 — Vision researchers at Barrow Neurological Institute have made a groundbreaking discovery into the optimization of light sources to human vision. By tuning lighting devices to work more efficiently with the human brain, the researchers believe billions of dollars in energy costs could be saved.

The research was conducted by Stephen Macknik, PhD, of Barrow's Laboratory of Behavioral Neurophysiology, and Susana Martinez-Conde, PhD, of Barrow's Laboratory of Visual Neuroscience. The study is published Proceedings of the National Academy of Sciences. The paper is believed to be the first attempt to tune light-emitting devices to the optimal temporal dynamics of the human visual system.

The discovery concerns the way humans perceive temporal modulations of light. For example, most light-emitting devices, such as light bulbs, video monitors and televisions, flicker. Faster flicker rates result in reduced perception of flicker, which is more comfortable to viewers. In studying this phenomenon in the brain, the researchers discovered that there is a range of flicker dynamics of light that optimizes the perceived brightness of the light without increasing power.

"We found a temporal sweet spot in visual perception that can be exploited to obtain significant savings by redesigning light emitting devices to flicker with optimal dynamics to activate visual system neurons in the human brain," says Dr. Macknik.

The researchers estimate that if every light-emitting device in the U.S. -- from light bulbs to cell phones -- operated at optimal efficiency for the human visual system, it could result in billions of dollars of savings in electricity and power.

To come to their conclusion, the researchers conducted experiments into two contradictory theories of temporal visual perception, or how bright a light appears. Bloch's Law states that the perceived contrast of a visual stimulus increases with its duration, but eventually plateaus at approximately 100 milliseconds. For example, a 5-millisecond flash will appear half as bright as a 10-millisecond flash, but a 200-millisecond flash will be just as bright as one of 400 milliseconds. The Broca-Sulzer Effect, on the other hand, states that perceived contrast increases with duration initially, but then peaks and falls again.

The researchers discovered that the discrepancy between Bloch's Law and the Broca-Sulzer Effect is caused by an intrinsic bias among experiment subjects, leading to dramatically skewed data. By improving their experimental design to overcome this bias, something that has never been before reported or intentionally controlled for, the results demonstrated that temporal vision actually follows the Broca-Sulzer Effect.

"Researchers have been studying temporal vision for more than 125 years, but because ours is the first experiment of its kind to control for all known forms of criteria, it is the first to accurately measure the role of temporal dynamics in brightness perception," says Dr. Macknik. "Thus, the power savings are ripe for the picking because we can adjust our lighting to flicker to take advantage of this peak in perception."

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The above story is reprinted from materials provided by St. Joseph's Hospital and Medical Center.

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Journal Reference:

H. Rieiro, S. Martinez-Conde, A. P. Danielson, J. L. Pardo-Vazquez, N. Srivastava, S. L. Macknik. Optimizing the temporal dynamics of light to human perception. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1213170109

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View the original article here