Motorcycle Monitor Accelerometers make it possible to know when a motorcycle is crashing and then fire a jacket airbag before the driver strikes the ground.

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Motorcycle Monitor Accelerometers make it possible to know when a motorcycle is crashing and then fire a jacket airbag before the driver strikes the ground.

Charles J. Murray, Senior Technical Editor, Electronics &Test -- Design News, March 1, 2011 For motorcyclists, few thoughts provoke more terror than the idea of flying headlong over the handlebars. Under those circumstances, they're at the mercy of velocity and impact, as well as the free-body forces that are generated when flesh and bones strike asphalt surfaces, concrete curbs and occasional moving vehicles.
Using accelerometers, the motorcycle determines if crash forces warrant firing of the airbag. Source: The Bering Co.
The good news, however, is that one clothing manufacturer understands the physics of the situation, and has a solution. The Bering Co., a French firm that specializes in wearable motorcycle gear, has rolled out a jacket that doubles as an airbag. Send it a firing signal and the jacket will puff up with 21 l of compressed helium, cushioning the cyclist's body before it strikes the bone-breaking surfaces.
"We can't stop the accidents, but we can provide the drivers with something protective to wear," says Francois Nicolas, a spokesman for Bering. "And the best way to do that is to give them an airbag jacket."
Indeed, a jacket does seem to be the most logical solution. Unlike car and truck drivers, who are tethered to their seats, motorcyclists are essentially projectiles, free from the confinement and safety of an enclosed vehicle interior. That's why a study conducted by the European Assn. of Motorcycle Manufacturers concluded that the risk of being killed in a motorcycle accident is 20 times higher than the risk in a passenger car.
Bering's new jacket isn't the first to try to deal with those dangers, but it is the first to apply wireless technology to the problem. It's also the first to allow the bike itself to decide whether it's time to fire the bag.
"We think the best way to identify an accident is to let the vehicle make the decision," Nicolas says. From the time of the crash to inflation of the airbag takes just 80 msec. Source: The Bering Co.
Building on Experience To be sure, others have also developed airbag jackets, but have made them work by fastening a cable between the jacket and the bike. As a result, those jackets actually use the airborne motorcyclist as a means to help determine whether a crash is imminent.
In contrast, Bering's airbag jacket calls for a team effort involving both the bike and the jacket. To make its decision on whether to activate the airbag, the product uses two key parameters: impact and loss of control. Working with engineers from U.S.-based Freescale Semiconductor, a major automotive supplier, Bering developed specialized modules to help detect a crash or a slide. A six-channel crash module, attached to the fork of the bike, uses a pair of two-axis accelerometers and a pair of single-axis accelerometers to look for deceleration in three axes (the devices are used in pairs for redundancy). When the accelerometers sense impact, they send analog signals that are processed by an 8-bit Freescale microcontroller on board the module. The module then sends the digitized data across a CAN databus to a separate interface module on the bike's steering bar. There, a 16-bit microcontroller processes the data yet again, using the firing algorithm to determine whether the airbag needs to be activated. If it decides to fire, then the interface module uses an RF link to "talk" to the jacket.
Freescale, which has worked on airbags since the inception of the technology two decades ago, says that the crash sensor is the same one used by the auto industry. "They had nearly the same needs as the automakers," says Matthieu Reze, automotive technical marketer for Freescale. "And since we had done it for automakers for so long, we knew exactly what they needed."
The airbag jacket uses accelerometers in the motorcycle's fork for sensing impact, and uses accelerometers under the seat to sense loss of control. Those modules send their data to an interface module on the steering bar. If a crash occurs, the interface module wirelessly notifies a microcontroller inside the jacket. Source: Freescale Semiconductor Click here for larger image.
Still, engineers found that motorcycle airbags had their own set of challenges. While the crash sensor looks for impact, a separate module under the seat watches for loss of control. Using an accelerometer and 8-bit microcontroller, this module analyzes whether the motorcycle is tilting too much. Here, Bering has departed from traditional automotive techniques, which are more likely to look for yaw than for tilt. To do that, however, the jacket maker had to study how loss-of-control accidents occur.
"They came up with a lot of different tests for professional bikers to do on test tracks," Reze says. "They had to determine what (tilt) angles were acceptable for the driver, and at what point the biker starts to lose control."
If the cycle exceeds that prescribed angle, the loss-of-control module takes note. Like the crash module, it sends its data via a CANbus to the interface module on the steering bar. The interface module "looks" at data from both modules, then decides whether to fire the bag.
If it does decide to fire, the interface module uses a wireless transmitter. It sends a signal to an 8-bit microcontroller in the jacket, which initiates airbag inflation.
Jacket inflation is accomplished by using a switch to open a small valve on a metallic helium bottle inside the jacket. When the valve opens, the jacket's lining fills with 21 l of cold helium gas. Bering says it used helium for good reason: A pyrotechnic explosion, typically used in car airbags, would burn the wearer of the jacket. Moreover, the helium solution offers another advantage: The airbag is filled - not just for a half-second or so, as is the case with a car airbag - but for a full six seconds, thus protecting drivers if they are thrown from the bike.
From the onset of the accident to the airbag inflation, the entire process takes just 80 msec, Bering says.

Freescale engineers believe the technology plows new ground. "This is not the first to have an accelerometer on the motorcycle's fork," Reze says. "But it's the first to have loss-of-control detection and it's the first to use a wireless solution." In the case of an accident, 21ℓ of helium gas flows into the jacket. Source: The Bering Co.

Testing the Market In November, Bering rolled out the Wireless Airbag Safety System to motorcyclists in France, and has since sold about 500 of them at a price of about 590 Euros apiece. Because the product is an aftermarket device, Bering has partnered with an electronics supplier, Tecno Globe, to do installation of the modules on motorcycles, and to program the bikes to work with the jackets.

"When you buy the jacket, you buy all the modules," Reze says. "Installation is done by professionals. You can't do it yourself."

Bering believes that the jacket has arrived just in time to help Europe deal with a proliferation of small scooters and motorbikes on its streets. "In France, scooters and little bikes are everywhere," Nicolas says. "People drive these motorcycles without any information or even a license. We think the best thing we can do is give them some protection."

For now, the technology is available only in France. The airbags in the jackets can be used multiple times before replacement is necessary, Nicolas says. Two jackets can be purchased per bike to allow for passengers.

Nicolas says that Bering has talked with motorcycle manufacturers about installing and selling the technology on newly manufactured bikes. "We've discussed the possibility with them," Nicolas says. "Kawasaki was the first to take notice, but we still don't know how it would work."

In the meantime, Bering and many motorcycle manufacturers will undoubtedly be watching to see how the public receives the new technology. "We'll do it in France and see how it works here," Nicolas says. "If it goes well, then we hope to do it for export."