The system works by sensing tiny changes in shadows on the ground to determine if there's a moving object around a corner. Such a system could be used by autonomous vehicles to avoid a potential collision with another car or pedestrian emerging from around a building's corner or from in between parked cars.
In the future, say the engineers, robots might also use the system when navigating hallways in buildings to avoid hitting people.
"For applications where robots are moving around environments with other moving objects or people," says Daniela Rus, director of the Computer Science and Artificial Intelligence Laboratory (CSAIL) and the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT, "our method can give the robot an early warning that somebody is coming around the corner, so [it] can slow down, adapt its path, and prepare in advance to avoid a collision. The big dream is to provide 'X-ray vision' of sorts to vehicles moving fast on the streets."
In a paper on their work, the researchers describe successful experiments with an autonomous car driving around a parking garage and an autonomous wheelchair navigating hallways. When sensing and stopping for an approaching vehicle, say the researchers, the car-based system beats traditional LiDAR - which can only detect visible objects - by more than half a second.
The system is based on an earlier project, called "ShadowCam," that uses computer-vision techniques to detect and classify changes to shadows on the ground. It uses sequences of video frames from a camera targeting a specific area, such as the floor in front of a corner, to detect changes in light intensity over time, from image to image, that may indicate something moving away or coming closer.
Some of those changes, say the researchers, may be difficult to detect - or even invisible - to the naked eye, and can be determined by various properties of the object