Sound vibrating a windowpane or through a tabletop is something most people experience daily. Sound waves travel well through most solid materials. Now, European researchers have exploited the excellent propagation of sound waves through solids to turn everyday objects – including 3D objects – into a new kind of computer interface.
By attaching sensors to solid materials, researchers from TAI-CHI, a project working with Tangible Acoustic Interfaces for Computer-Human Interaction, were able to locate exactly and track acoustic vibrations. Tapping on discrete areas of a whiteboard could generate musical notes on a computer. Tracking the sound of a finger scrawling words on a sheet of hardboard could translate, in real time, into handwriting on a computer screen. There is no need for overlays or intrusive devices.
Sensing vibrations in a solid and converting them to electrical pulses is the easy bit. Exactly locating the source of that vibration in a solid material is where it gets complicated. The problem is that the complex structures of solids make wave propagation difficult to model. Wood knots in a desktop, for instance, will alter how acoustic vibrations disperse.Reading the signals
Time reversal, on the other hand, needs only a single sensor. It works on the notion that each location on the surface of a solid generates a unique impulse response which can be recorded and used to calibrate the object. Time reversal works on 3D objects just as well as flat surfaces.
MUlti-Sensor Tracking through the Reversal of Dispersion (MUST-RD) requires a deep understanding of the wave-dispersion properties of the solid. The dispersion curve of acoustic waves moving through the material under test is compared to a database of dispersion curves for common materials. From the comparison, the location of the vibration source can be calculated. (MUST-RD can also be used to give a crude estimation of a material type.)
Finally, TAI-CHI researchers worked with in-solid acoustic holography. Using sound pressure, sound intensity or particle velocity to calculate position and time, a sound source can be mapped and visualised in much the same way as an infrared camera can map heat sources. Some of the TAI-CHI researchers also experimented with a combination of acoustic localisation and Doppler tracking to locate and track sound sources moving through the air.
The range of researchers brought together by the project, part-funded by the European Commission – in Germany, France, Italy, England, Wales and Switzerland – was an important factor in its success, according to TAI-CHI coordinator, Dr Ming Yang of the University of Cardiff.Specialist solution
“Time reversal is a beautiful technology,” he says. “Unlike TDOA, it works with any object and it does not require special materials. Because it needs only a single sensor and a normal computer, it is very simple and cost-effective. One spin-off company from the University of Paris is working on commercial applications for this.”
Other technologies, such as acoustic holography, show great promise but are not ready for commercialisation.
CeTT, a Swiss member of the consortium, has put together a TAI-CHI Developer’s Kit, comprising algorithms developed during the project, software and hardware, as a one-stop-shop for application developers looking to build on TAI-CHI breakthroughs.
Other applications include a wireless sensor using Bluetooth technology that Dr Ming Yang would like to develop with commercial partners.
The time-reverse technology is the project’s major breakthrough, according to Dr Ming Yang. “Before, people were only working on easy materials. We have developed it for metal, plastic and board. We have a really interactive interface.”
Christian Nielsen | alfa
Cutting edge research for the industries of tomorrow – DFKI and NICT expand cooperation
21.03.2017 | Deutsches Forschungszentrum für Künstliche Intelligenz GmbH, DFKI
Molecular motor-powered biocomputers
20.03.2017 | Technische Universität Dresden
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy