Smart Tires--Look for new sidewall torsion sensors in an '02 model

Continental AG plans to consummate the marriage of tires and technology early next decade with the debut of its "intelligent tire," the first technology to determine the longitudinal and lateral forces acting on a tire - and translate that information into meaningful vehicle-dynamics enhancement.

The Frankfurt, Germany-based company says its sidewall torsion (SWT) sensor, the primary component of the intelligent tire system because it measures the forces at work between the tire and the road surface, should debut on a production vehicle within the '02-'05 model years. It is estimated that the technology likely will debut on a German automaker's product, probably in Europe, where Continental records 64% of its revenue.

Continental expanded into complex chassis components when it purchased the ITT Automotive Brake and Chassis unit from ITT Industries Inc. in 1998 for $1.93 billion. It showed off a working prototype of the system to the media prior to the Frankfurt auto show last month.

It's the first glimpse of a technology that Continental has been talking up for nearly two years. The company says its system will reduce costs because it eliminates the expensive yaw-rate sensor - currently a crucial item in contemporary stability control systems that actively intervene to correct an under- or oversteering vehicle that's potentially skidding out of control.

Continental also says the SWT should deliver shorter braking distances because of a more "direct" information route between tire contact patch and antilock braking systems. But Continental admits a lot of work remains. "It's still in the development stages. We have a ways to go. But there is potential (to reduce costs and improve function)," says a Continental engineer.

The SWT's responsibility is to deliver more information about the behavior of the tire by measuring the tire's sidewall deformation - a tire deforms around its entire circumference when it transmits lateral (cornering) or longitudinal (acceleration/braking) forces. There are two sensors that collect data from a tire specially made with 96 magnetic fields (located along the tire's inside wall to prevent mechanical problems). Both sensors are attached to the chassis; one is close to the tread, the other is close to the rim. Measuring the difference in magnetic fields at the two sensors provides the required information about tire deformation.

Continental anticipates the intelligent tire can significantly aid other vehicle systems such as adaptive cruise control.