Sit back and relax

Purdue University engineers have developed a ‘sensing chair’ that they believe can determine a person’s sitting posture, research that could lead to use in applications such as computer-security systems and the design of more comfortable furniture. The modified office chair uses software algorithms that interpret information collected by an array of pressure sensors in the backrest and seat.

When tested on 30 people, the chair demonstrated an overall accuracy of 96 percent in determining whether people were slouching, leaning in various positions, crossing their legs or sitting upright.

‘The chair senses how the pressure is distributed in the seat and the backrest,’ said Hong Tan, an assistant professor at Purdue’s School of Electrical and Computer Engineering. ‘We train the computer to recognise pressure patterns associated with different seating postures by showing the computer examples of such patterns.’

Software enables a computer to interpret a person’s posture by analysing pressure patterns, which are represented by thousands of numbers fed to the computer by numerous sensing elements, or ‘sensels,’ in the chair.

Each time a person sits in the chair, the computer creates precise ‘pressure maps’ that can distinguish between different people, even if they are sitting in the same position.

The system is limited in that it is capable only of sensing ‘static posture,’ or how a person is sitting at any one given time.

‘Currently, we are working on a dynamic system so that we can see how people are moving, throughout an eight-hour day, for example,’ said Tan.

Such an advanced ‘real-time sitting posture tracking system’ could lead to many applications. Because the system would be able to recognise the pressure patterns unique to specific people, a potential application might be to verify authorised personnel for computer-security purposes.

A sensing chair also might be used in cars to automatically adjust the driver’s seat according to who is behind the wheel, or to control an airbag’s deployment by adjusting for a person’s seating position and weight.