Bendix explains stability control confusion

| 8/1/2008

Electronic safety equipment that helps a driver correct after a sensor tells the truck to do so sounds simple. In truth, unless you have an engineer’s brain, it’s extremely complicated technology.

Bendix has released a “white paper” to familiarize truck buyers and users with full vehicle stability control systems, known as ESP or ESC (electronic stability program or electronic stability control) and how they differ from lower cost roll stability programming or control (RSP or RSC).

“There is confusion about stability programs,” said Fred Andursky, Bendix director of marketing for controls.

In a media conference this week in Elyria, OH, Andursky said even truck dealers were confused.

“While 81 percent of dealers knew of stability systems, only 28 percent recognized the differences between the two,” he said.

All stability systems start with the truck’s ABS system. Roll stability systems have a single sensor to measure changes in lateral acceleration, while Bendix’ full stability control systems, ESP or ESC, include yaw sensors, steering input sensors, load sensors and brake pressure sensors.

The yaw rate sensor measures what the truck is doing. The load sensors help proportion the forces to be applied by the electronic controls. The steering angle sensor and the brake pressure sensor measure driver intent, so the computers actually assist the driver in maintaining stability by increasing the truck’s stability margin.

Rather than taking control from the driver, ESP/ESC helps good drivers do a better job during unanticipated events. The systems are always on, but are not intrusive. They have proven effective in 68 percent of incidents during testing.

No matter how good any system is, these stability systems cannot overcome the laws of physics. In many cases, they mitigate crashes rather than preventing them, turning what might have been an injury crash into a fender bender.

Full stability systems like ESP/ESC are more effective because not all rollovers occur on curves. Crash causation studies show that about 53 percent of the 13,000 annual total take place on straight roads, when drivers swerve to get back into their lane or to avoid a car, pothole or other obstacle. These systems can help reduce rollovers, at a cost of about one percent of the price of a truck.

Bendix expects ESP/ESC to list in the $1,600 to $1,900 range, compared to $800 to $1,000 for RSC. A bill currently in Congress, HR3820, will provide tax incentives for such safety devices, if it passes.

– By Paul Abelson, senior technical editor
Paul Abelson can be reached at