Motorcycle Safety Achievment in Design
Motorcycle safety equipment has come a long way from the pudding-bowl helmets and unreinforced leathers of yesteryear, providing significantly better protection with plastic armor inserts, abrasion-resistant materials, range-limiting joint and neck protection, and of course, superior helmets. However, injuries still occur, sometimes serious.
Ten years in the making, the Dainese D-Air shoulder, neck and collarbone protector deploys in the event of an accident, offering additional padding against impacts as well as restricting hyper-extension of the neck- an event often responsible for spinal cord injury.
Mounted to the shoulders of a specially adapted leather racing suit, D-Air replaces the suit’s usual aerodynamic hump with a self-contained housing weighing about 25 ounces. The new hump holds a GPS receiver, various accelerometers, a hybrid gas generator, a processor to evaluate data (and trigger the airbag infl ator), lithium batteries, and the airbag envelope.
As well as the obvious packaging issues, the operation of a motorcycle rider-based airbag is an extremely challenging concept. There are some accidents when the sudden ballooning of a cushion at the rider’s shoulders might do more harm than good, by initiating a tumbling motion when the rider was already sliding harmlessly. Determining exactly when to deploy the airbag is the crucial decision, and it is a judgment that is not easily made.
A considerable amount of research went into computer simulations, and into instrumented crashes with dummies and stunt riders aboard. To help the engineers recognize accident thresholds, data logging was carried out on riders racing at various venues (including the Isle of Man) to determine what could be considered normal motion signatures.
Alessandro Bellati, one of the D-Air’s development engineers, explains: "What we discovered during the development was that the system shouldn’t trigger during just any crash. During certain crashes, it is better that the rider just slide-away, because regular protection behaves well enough and an airbag system wouldn’t help the rider to assume the correct position for sliding. In this scenario, the system behaved well,
because we were able to tune it to react only to certain sufficiently strong events. We discovered that not only was it possible to distinguish data between regular riding and crashes, but also between different kinds of crashes. So, then we could tune the system accordingly."
Because processing speed is so high, the computer continues to monitor incoming data after a crash threshold is recognized. The system waits for confi rmation before triggering the on-board hybrid gas generator to infl ate the airbag in 1/25th of a second.
Various conditions have to be met for a real crash to be identified. Compare that to a car airbag system, where accelerometers simply respond to a violent deceleration event. In the D-Air, the processor is looking at the GPS sensor for speed and position, at three angular velocity sensors for rotational data, and at three linear accelerometers.
It is a wealth of information to analyze, and the rest is software tweaking to arrive at the appropriate algorithm; but the simplicity of that statement belies the magnitude of the challenge. As Bellati admits, "In the very early stages of development, nobody was sure if it was even possible to identify the crash of a rider while it was happening."
Compare that to the situation at the MotoGP races at Valencia in 2007, where three prominent riders used D-Air Racing systems, and where all of them experienced airbag deployments in real crashes. For racers, an added benefi t of the D-Air Racing device is that it can be quickly removed should the rider wish to remount and continue. Similar systems for road motorcyclists, called D-Air Strada, will soon be available.
Crashing is certainly a topic we all prefer to keep a theoretical concept, rather than a practical issue. To our benefit, the Dainese D-Air Motorcycle Airbag System converted the theoretical to the practical, with the promise of saving lives and maintaining body integrity when the unthinkable happens. ULTIMATE MOTORCYCLING FEBRUARY / MARCH 2009