Smarter car algorithm shows radio interference risk

An experiment at the Massachussetts Institute of Technology has highlighted some of the hidden risks inherent in (supposedly) smart cars that will depend on radio-based Intelligent Transport Systems (ITS) for extra safety on the road.

In an ITS system, in-car computers communicate with each other over vehicle-to-vehicle (V2V) microwave radio links, while the cars also communicate with traffic lights and roadside speed sensors over a vehicle-to-infrastructure (V2I) radio signalling system (the infrastructure transmits information about cars that are too old to have ITS systems fitted). When two cars are approaching a junction and the V2V/V2I speed signals suggest they are going to crash, a warning can be sounded or a software algorithm can choose to make one of the cars brake, for instance.

I tried this out on the Millbrook test track in Bedfordshire, UK, in 2007: speeding towards a junction in a Saab my brakes were automatically applied to allow a speeding Opel to pass in front of me. It was by turns scary and impressive. But if it hadn't worked I'd have been toast.
But MIT engineer Domitilla Del Vecchio says such systems can be over-protective, taking braking action when there is no real threat. "It's tempting to treat every vehicle on the road as an agent that's playing against you," she says in an MIT research brief issued today.

So she and researcher Rajeev Verma set out to design an algorithm that doesn't over-react - and to test it with model vehicles in a lab. Their trick was simple: calculate not speed but acceleration and deceleration as cars approach a junction, allowing a much finer calculation of the risk. In 97 out of 100 circuits, the collision avoidance technology worked fine.

But in three cases, there were two near-misses and one collision. The reason? Nothing to do with the algorithm: it was due to delays in V2V and V2I radio communication. This highlights the risk of depending upon a complex safety system like ITS - especially a radio-based one which could easily be jammed or electromagnetically interfered with because of the wireless technologies which proliferate in our built environment.

There is only so much that researchers can do against a phenomenon as difficult to predict as radio interference.
The takehome message? ITS technology will doubtless do much to improve road safety - but sometimes it won't. It's never going to substitute for driver alertness.

Source New Scientist