Magnetic sensors can measure distances between vehicles

Every vehicle has a magnetic field, and researchers have now found that a vehicle’s magnetic field has an inverse relationship with distance at small distances. The relationship provides a way to estimate a vehicle’s position using its magnetic field when the vehicle is less than a few meters away, which could be useful for detecting imminent collisions just before they occur.

S. Taghvaeeyan and R. Rajamani of the University of Minnesota have published their study on using vehicles’ magnetic signatures for position estimation in a recent issue of Applied Physics Letters.

“The main sources of magnetic fields are the magnetized steel belts in the tires, the ignition, the alternator, air conditioning system, speakers, etc.,” Rajamani told “The significant metal in the engine block, transmission, driveline, etc., can also be magnetized.”

The magnetic field technique is not the first attempt at measuring inter-vehicle distances. Currently, some luxury vehicles use radar or laser sensors to measure distances to other vehicles. However, these sensors have two drawbacks: they cannot measure distances of less than 1 meter, and a typical radar distance measuring unit can cost over $1000. In comparison, the AMR sensors can measure distances of less than a meter and cost less than $10.

By further improving these sensors and tailoring them for commercial use, the researchers envision that the sensors could be applied all around a vehicle’s body, where they could detect nearby vehicles in all directions.

“The sensors will be useful for detecting an imminent collision,” Rajamani said. “The sensors will provide information on the relative velocity and position of the impending crash on the vehicle. This could be used to pre-tighten seat belts, inflate airbags and deploy other active structural enhancement measures that can protect the occupants in the car during the crash.”

Source: physorg.comAdded: 20 October 2011