Apple iPhone turns table top into full-sized invisible keyboard

A student has developed software that allows the iPhone to turn any table into an impromptu, invisible full-sized keyboard by analysing the vibrations caused by fingers tapping the surface.

The system, dubbed Vibrative, uses the three-dimensional accelerometer in Apple’s smartphone to measure the characteristics of each tap on the table, such as the strength and frequency of the vibrations it causes, and compares them to “training data” to work out its approximate location.

The location is converted into a key press on the "virtual keyboard". Currently, the system determines the intended key correctly about 80 per cent of the time, so the data is also fed into an auto correct dictionary to ensure the words are spelled correctly.

“The signals I’m collecting are very weak,” said Florian Kraeutli, a computing student at Goldsmiths, who created the system as part of his work on user interfaces.

“At the moment it’s more of a proof of concept but if you made the accelerometer more sensitive you could improve the accuracy quite easily.”

He suggested that accelerometers in smartphones may be set to be less sensitive than they are capable of to conserve battery power. The system is currently more accurate on smaller surfaces, which vibrate more with each tap.

The system needs to learn the vibration patterns for each surface on which it is used, but does not necessarily need to be taught the patten for each key individually.

"Ideally you would train each key, but you can do just a couple," said Mr Kraeutli.

In a video demonstrating the technology, Mr Kraeutli uses a “keyboard” printed on an ordinary piece of paper to train Vibrative and then type a text message. He also shows the paper is unnecessary for a touch typist, once the system is trained, by typing directly onto the wooden table beneath.

Mr Kraeutli used a “jailbroken” iPhone 4 to create the software, as Apple normally does not allow apps to change the way the iOS keyboard works. Android does not have similar restrictions, and downloadable "smart" keyboard apps such as SwiftKey, which has advanced predictive technology, have blossomed.

Vibrative could easily be converted for other smartphones, said Mr Kraeutli.