Boning up on safety

Cars could be fitted with a scanning system to estimate the occupant’s bone strength and tune the seatbelt and airbags accordingly to improve safety during crashes and reduce injuries caused by the restraints.

The system, being developed by a consortium including Nissan’s European technical centre and the Cranfield Impact Centre, consists of an ultrasound finger scanner and processor. It would take the finger reading and use it to estimate the skeletal strength of the rest of the body — in particular the chest, which can be injured by seatbelts contracting too forcibly during accidents.

Sensor systems to adjust the deployment of airbags to the size and seating position of drivers and passengers are already being developed by car makers and their suppliers. But these systems provide only limited information.

By scanning the bone strength of each occupant, the system would be able to assess their injury tolerance limits. This would allow it to offer the maximum protection for a specific impact without damaging the weaker ribs of children and pensioners.

The system could be built into the dashboard or the driver’s door, or if miniaturised sufficiently could even be integrated into the gear lever, said Roger Hardy, technical director of the Cranfield Impact Centre, a consultants specialising in vehicle crashworthiness owned by Cranfield University. It would be used each time the car’s engine was switched on, before the driver was able to move off, he said.

‘In its crudest form it would be a hole into which you put your finger, and the instrument would then be powered to lightly grip the finger, take the reading and then release,’ he said.

‘This would then feed into the restraint system, part of a processing unit in the car, in addition to what is routinely used to detect a go/no-go situation for firing airbags.’

The system would decide what level of force the seatbelt pretensioner should apply, and if necessary reduce this force slightly to ensure that it gives a little once the car has begun to decelerate. For cars with dual-stage airbags, the system would decide whether to fire both stages, just one, or introduce a time delay before the second stage is fired.

In hospitals ultrasound scanners are used with gel to improve their signal, but this would obviously be impossible in a car, so the team is investigating the use of a gelimpregnated pad. This has so far proved difficult, and will require further work, said Hardy.

Ultrasound was chosen for the scanner as it uses no ionising radiation, making it a safer and lighter option as it does not require a heavy power source to generate sufficient energy. As ultrasound is used routinely in foetal scans, it is also likely to be more readily accepted by the public.

The scanner uses quite high voltages, but works in pulses so would not interfere with the engine management system, said Hardy.

The Bone Scanning for Occupant Safety (BOSCOS) project, received funding under the SMMTled Foresight Vehicle programme, and also includes TRW Automotive, car safety systems specialist Autoliv, UK ultrasound bone measuring system developer McCue, and Cranfield and Loughborough universities.

The team is now putting together its final report on the project, and the consortium partners will then assess whether the concept requires further investigation, or if the technology is ready to be developed into a commercial device.

The system is likely to be fitted to cars at the top end of the market initially, although its cost would be no higher than many other options facing new car buyers, according to Hardy.