On the flat

Sensors developed for Europe’s space programme have been used to build a system that allows any flat surface such as a wall, window or tabletop to become interactive.



The technology, called ReverSys, lets users turn lights and music off and on or operate the television without leaving their chair. This removes the need for remote controls and could allow light switches to be moved without altering wiring.



Developed by Sensitive Object together with Nodal Consultants, part of ESA’s Technology Transfer Programme, ReverSys uses an accelerometer to determine exactly where a surface is being touched. Accelerometers are used in conjunction with gyroscopes to form the inertial positioning system on-board Ariane launchers. They also turn on the pyrotechnic switches that control the fuelling of the boosters and are used on satellites. When a surface is tapped the accelerometer can accurately measure the sound waves produced in order to determine the location of the tap, allowing any surface to become as sensitive as the keys on a computer keyboard.



A tap on a flat surface produces a unique acoustic signature, as waves emitted even by taps separated by very short distances are diffused differently. The measurement is made using a physical process called temporal reversal that precisely identifies the point of a source of emitted sound waves.



ReverSys is managed by a computer containing a programme that links touch at a specific location to a specific action. Once the accelerometer picks up sound and recognises a particular signature, the intended action is executed.



‘The system is based on vibration technology so an accelerometer was needed,’ said Nicholas Delorme of Nodal Consultants. ‘Once the software was developed using an expensive but very accurate space sensor the company could change to using a cheaper accelerometer like those used in car airbags.’



ReverSys can be used with materials such as glass, wood and even brick walls, allowing control panels to be located wherever is convenient. There are no wires and the surface does not need to be modified. The control panel can also be easily modified or moved if necessary.