As some readers may already know, Volvo recently developed a system that uses an in-vehicle radar system to alert drivers to the presence of pedestrians and cyclists on the road in front of them. Now, Germany's Technische Universitaet Muenchen has come up with a system of its own, that can even detect pedestrians that aren't within line of sight of the car.

In the university's Ko-TAG system, pedestrians and cyclists carry a transponder – this could be a small wearable device, or it could simply be built into their smartphone.

Cars, on the other hand, transmit a coded radio signal. As a vehicle gets within range of a pedestrian, that person's transponder picks up the signal and responds by altering the code, then transmitting it back to the vehicle "in a very precise temporal pattern." By analyzing that pattern, the vehicle's onboard positioning system is able to determine the speed and trajectory of the pedestrian.

By combining the originating location of the return signal with the car's own present GPS coordinates, it's also able to determine the pedestrian's location to within a few centimeters – and it does so within a few microseconds. If it determines that the car and the person are about to collide, it can alert the driver or even automatically apply the brakes.

One of the system's big selling points is the fact that, unlike radar-based technology, it can detect pedestrians even when they're hidden from view. This could save people from being hit when walking out from between parked cars, or other objects.

Volvo is likewise working on what it calls a "car-to-cyclist communications system," although details on how it works have yet to be released.