Mandatory Stability Control

Mandatory STABILITY CONTROL

ROUNDUP

Are future motorcycles going to have government-mandated electronic safety features?

KEVIN CAMERON

STABILITY CONTROL MEANS ONE thing for cars and quite another for bikes. For cars, it means placing a yaw-sensing device near the

vehicle's center of gravity, which detects over-rapid rotation around the vertical axis, indicating the vehicle is spinning out as a result of either over-braking or wheelspin. The vehicle's computer then takes appropriate action to end the cause of the rapid vehicle rotation.

The National Highway Traffic Safety Administration believes that such an Electronic Stability Control can eliminate 26 percent of single-car crashes and cut 48 percent of single SUV crashes. It is for such reasons that ESC is to become mandatory on U.S. autos in 2012.

First applied by Mercedes in 1995, ESC is said by Consumer Reports to be already implemented as of 2009 on 73 percent of all cars and on 99 percent of SUVs. Note that such systems can be helpfiul only if the undesired yaw is being caused by wheelspin or overbrak ing. ESC cannot create extra traction where there is too little, so if you drive your ESC-equipped car into a turn too fast for the available grip, farewellyou're on your own, Schumie.

In 2007, along came BMW with a motorcycle system they call ASC, or Automatic Stability Control. It does not include a yaw sensor, so in that sense it is not a yaw-control system. Instead, it attempts in a unified way to stop deviations that could lead to yaw before it occurs. It includes wheelie "lift-off detection and intervention" and wheelspin detection and interven tion during rapid acceleration. But if, in the middle of a turn, the motorcycle begins to slide out at front or rear, this system cannot detect the sliding or take action against it.

Why no yaw control for motor cycles? Almost 20 years ago, thenChief Engineer of Harley-Davidson Earl Werner proposed the rhetorical question, "Why not yaw control for motorcycles?"

For starters, motorcycles must lean over to go around turns, and having short wheelbases, sliding mo torcycles can yaw beyond control in the twiniding of an eye. Valentino Rossi is a magical stability system, for which Yamaha pays him all those millions. A simple yaw sensor would need to know the machine's roll angle in order to measure yaw, and an effective recovery system would have to control the machine's steering. Now that even mighty Toyota is suspected of software glitches, is anyone ready for motorcycle steer-by-wire? And that might not be enough, because we know that expert riders recover from undesired yaw using a variety of techniques, including the fabled knee save, judicious-but-counterintuitive application of throttle (are you listening, Freddie?) and vigorous body English. Hard to imagine an electronic system with knees and a human body.

"Valentine Rossi is a magical stability system, for which Yamaha pays him all those millions."

This makes it appear that BMW's lim ited approach-stopping potential causes of unwanted yaw before it appears-is all that can currently be economically justified. Even on cars, there has to be some limit to how much electronic trickery the average person's transportation budget can afford. That leaves us with a lim ited motorcycle system based onABS, anti-spin and anti-wheelie, orchestrated to a common purpose.

It is estimated that 40 percent of the price of autos is now associated with "compliance"-fuel conservation, emissions, mandated durability, on board diagnostics and soon ESC. Safety is certainly desirable, but at some point, automatic devices begin to foster the opposite-complacency. Remember the pilots who dozed as their commercial airliner overflew its destination in Japan and headed for China? That airplane was so automated that there wasn't enough pilot workload left to keep the crew awake.