A new approach to car alarms gets vehicles to watch each others鈥� backs like a herd of animals under threat from predators.
The security system relies on networks of cars constantly gossiping with their neighbours using concealed wireless transmitters. The cars raise the alarm when a thief tries to make a getaway with any of their number.
鈥淢ultiple sensors hidden within the car would make it difficult, if not impossible, for a car thief to disable the system in a short period of time,鈥� says from Frostburg State University, Maryland, US, who designed the system 鈥� called SVATS (Sensor-network-based Vehicle Anti-theft System) 鈥� with colleagues at Pennsylvania State University.
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The design of the network should also produce fewer false alerts than traditional car alarms, he says.
Talking cars
Before leaving a vehicle, its driver uses a remote control to switch on the transmitters inside it. They send out a 鈥渏oin鈥� message to all the nearby cars.
After communicating with other vehicles, the car chooses its nearest neighbours to act as its sentinels. It does this by choosing partners that need the lowest signal strength for communication, to prevent the system sapping too much energy from the car鈥檚 battery.
The car sends out periodic 鈥渁live鈥� signals to these watchers, until the owner returns when it sends a 鈥済oodbye鈥� message. If the 鈥渁live鈥� messages cease without a farewell, then the watching cars report a theft by relaying a message to a central base station.
An alarm would then notify the security guard of the car park, the owners of the vehicle, or the police.
Vote of alarm
The system can also detect when a car is moving unexpectedly by measuring the signal strength of any 鈥渁live鈥� messages. If a car detects significant changes in signal strength, it sends a warning message to other cars monitoring the same vehicle, because it is likely to be moving.
However, it is only when a watching car receives more than three such warning signals from different sources that it will send out a theft alarm message to the base station. Ensuring that multiple cars must agree on a threat before the alarm is raised should cut out the false alarms that plague other anti-theft systems, say the researchers.
The system was tested using a small number of cars, with researchers driving off in some cars to see what would happen. SVATS detected all such 鈥渢hefts鈥� within just 4 to 9 seconds. It also seemed resistant to false alarms caused by weather, or people walking around the car park, both of which can affect the signals between sensors.
Accidental benefits
Paul Burnley, a car security expert from automotive consultancy , points out that most thefts occur when a car鈥檚 keys are stolen, which would likely mean they could legitimately disable the system.
He points out, however, that the kind of communication system imagined would have other valuable uses besides security, such as reporting car crashes on the motorway. 鈥淚t鈥檚 an interesting idea that does have some merit,鈥� he says.
(pdf) was presented at the in Phoenix, Arizona, US.
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