Further Up on Kinect-Style Motion Sensing: Ultrasound?

antartikaraya@blogspot.com.- Gesture-based control has become so vast they seem almost commonplace. We casually flip through the photos on our smartphones and had no problem swinging our arms back and forth in front of an Xbox Kinect. However, both touchscreens and camera-based recognition systems require special hardware. At Microsoft, researchers have created a program called Soundwave who only need speakers and a microphone.
The sound may seem like an unusual choice for motion-recognition after all, changed hands no need to make any noise. But Soundwave does not try to detect the sound of your hand. Instead, the speaker plays an ultrasonic tone, one of the high-pitched enough to be heard for the user. Microphone then detects changes in ultrasound and interpret the change as a movement.
Sidhant Gupta, a graduate student at the University of Washington, stumbled upon the idea while working on different projects. While measuring the frequency of 40-kHz ultrasound waves, he saw that the computer was acting strange microphone, capturing rogue signals at 39 and 41 kHz. "I thought it was a loose wire and that I had to fix it."
Even after double checking that all connections are secure, abnormal signals persist. He then realized that it was not damage the equipment. Ultrasound waves are the result of phantom kicks his legs bouncing up and down in his chair, produced by any high school physics: Doppler effect. Think of an ambulance siren as raising roads. Changes in pitch you hear is determined by the Doppler shift formula. If the sound source zooming towards you, you get more of the sound waves, so the higher frequency and high-pitched siren. If it drove away, the opposite happened.
When Gupta sat silent, sound waves bounce off of his feet and back into the computer's microphone, register as 40 kHz. However, when he began to get nervous, bouncing sound waves seemed to move toward and away from the microphone. Restless legs produce a small change, but measurable, in frequency. Based on the pattern of these changes, he wrote a program that is recognized if the leg moves up or down and expanded to detect other types of movement and motion.


Although it uses the Doppler effect to track human movement has been around for a decade, it is always necessary equipment adjusted. Soundwave eliminates the need for special hardware, requiring only basic technology. Computers, cell phones, and other electronics that have been equipped with speakers and a microphone.
Microsoft does not want to revolutionize motion control with ultrasound. And Morris, other researchers involved with Soundwave, imagine the program more as a supporting actor than the one-man show. Soundwave will not replace the Kinect, but it can work next to it and make it better by making more accurate recognition of movement in the direction of more. "Computer vision is not perfect, so whatever you can do to provide more information to make [gesture recognition] is more accurate."
If there is a concern about Soundwave, it is that the technology relies on a limited range of adult hearing for ultrasound pulse to be known, but not all of the hearing has been significantly reduced. For example, products such as the antiloitering Mosquitoes play a similar vein to specifically target and irritate the ear is more sensitive adolescent, and Bhiksha Raj, a professor of computer science at Carnegie Mellon University, concerns about side effects of Soundwave in children and pets. "Do not get me wrong, the premise is brilliant," he said, "but you know what happens when you hear a high-pitched tone they should take care of this problem before .."