Steering toward greater stability - WIP - Continental-Teves North America demonstrates its ESP II stability system

Automotive Design & Production, Dec, 2002 by Christopher A. Sawyer

Continental-Teves North America [Auburn Hills, MI) is demonstrating its ESP II stability system, but keeping mum about its customers. It has all of the expected Features--AB5, traction control, electronic brake Force distribution, and yaw control--and an important new Feature, electro-hydraulic steering [EHS]. EHS can be programmed to do a number of things, including changing responsiveness with speed and steering angle (think parallel parking versus highway driving), and responding to external Forces in such a way that vehicle directional stability is enhanced. It's this Feature that sets ESP II apart From its predecessor. And I recently had the opportunity to prove this to myself.

The First braking run on the split-coefficient surface was made in a vehicle Fitted with the First generation system. Just as expected, it was necessary to enter a quick counter-steer Force, and adjust steering input as the car came to a stop. Nothing dramatic--steering angles hit peaks between 200 and 400 per second-and easy to control. Switching the EHS system produced dramatic results. Entering the course at the same speed and braking at the same point produced...no drama at all. Steering angle peaks Fell into the to 5[degrees] to 10[degrees] per second range, with Far Fewer steering inputs necessary to stabilize the car. The reason For the difference was simple, on surfaces with different Friction coefficients, the EHS system actively counter steers to maintain directional stability. Repeating the entire exercise only served to illustrate just how dramatic a difference adding the steering into the control equation made to driver comfort and vehicle stability. And, says William Kozyra, president of Contine ntal-Teves North America, "Not only does this technology reduce stopping distances on these surfaces, the system can be expanded to include an extension that adds control of an active suspension system For even greater safety and responsiveness."

Though reticent to name automakers who are using the system before the official announcement, Continental-Teves will be supplying BMW with electro-hydraulic steering systems For the next generation BMW 5-Series. It's only a small leap to assume ESP II will be part of that car's vehicle dynamics package.