Now smartphones help raise fuel efficiency

In July, at the Association for Computing Machinery's MobiSys conference, researchers from MIT and Princeton University took the best-paper award for a system that uses a network of smartphones mounted on car dashboards to collect information about traffic signals and tell drivers when slowing down could help them avoid waiting at lights.

Where previous experimental traffic-light advisory systems used GPS data or data from traffic sensors, SignalGuru uses visual data from cellphone cameras. Graphic: Christine Daniloff

By reducing the need to idle and accelerate from a standstill, the system saves gas: In tests conducted in Cambridge, Mass., it helped drivers cut fuel consumption by 20 percent.

Cars are responsible for 28 per cent of the energy consumption and 32 per cent of the carbon dioxide emissions in the United States, says Emmanouil Koukoumidis, a visiting researcher at MIT who led the project. ''If you can save even a small percentage of that, then you can have a large effect on the energy that the US consumes,'' Koukoumidis says.

The system is intended to capitalise on a growing trend, in which drivers install brackets on their dashboards so that they can use their smartphone as a GPS navigator while driving.

But unlike previous in-car cellphone applications, the new system, dubbed SignalGuru, relies on images captured by the phones' cameras. According to Koukoumidis, the computing infrastructure that underlies the system could be adapted to a wide range of applications: The camera could, for instance, capture information about prices at different gas stations, about the locations and rates of progress of city buses, or about the availability of parking spaces in urban areas, all of which could be useful to commuters.

Koukoumidis is a student of Li-Shiuan Peh, an associate professor in the Department of Electrical Engineering and Computer Science who came to MIT from Princeton in fall 2009. Koukoumidis came with her, and together they launched the SignalGuru project as part of the Singapore-MIT Alliance for Research and Technology's Future Urban Mobility program. Koukoumidis's other thesis advisor, Princeton's Margaret Martonosi, is the third author on the MobiSys paper.