Emergency Steer Assist from Continental supports obstacle-avoidance maneuvers

  • 25-Jun-2010 11:52 EDT
Emergency Steer Assist diagram.jpg

Continental says a typical driver traveling 100 km/h (62 mph) on a dry road surface needs to initiate an emergency stop at about 40 m (130 ft) to avoid a stationary obstacle. The distance to avoid a collision with steering alone is about 30% less. Emergency Steer Assist (ESA) helps the driver keep the vehicle on the optimum trajectory during the avoidance maneuver.

“Now!” the engineering expert barks from the passenger seat. I turn the steering wheel hard to the left, then back to the right, and easily avoid the obstacle I was sure to hit—without any hint of oversteer.

The obstacle was only a balloon car and posed no threat even if I had barreled into it. Still, purposely racing straight toward any static object at 90 km/h (55 mph) before making a last-second avoidance maneuver can be intense.

The technology assisting with the near miss, Continental’s Emergency Steer Assist (ESA), interacts with other technologies already available and on board some production vehicles, such as electronic stability control (ESC), electric power steering, electronic air suspension, and actively steered rear axles. This technology integration was demonstrated in a BMW 5 Series on the supplier’s test track near Frankfurt, Germany.

The key to ESA, according to my passenger, Bernd Hartmann, Chassis Systems Advanced Engineering manager in the Chassis & Safety Division, is the integration of sensors. “The main breakthrough came with this idea to combine [existing] chassis systems with surrounding sensor systems to make it intelligent,” he said. “Everything that we’re doing depends on the surrounding sensor system.”

The technology’s first stage will employ only radar sensors, such as those used for adaptive cruise control. The advanced engineering department is working to combine video images from camera systems with the radar signals. The reason is simple: “The more we see, the better the support,” Hartmann said.

Mandatory for ESA is the distance sensor, electric power steering, and ABS/ESC. A chassis and safety controller—a central ECU in the vehicle—can optimize the interaction between the different safety systems. The other technologies merely provide more functionality.

During several passes on the test track, with speeds increasing each lap from 40 km/h (25 mph) up to 90 km/h, the car became increasingly easy to control as Hartmann added more functionality to the system. The rear axle steering (with ±2° movement) increased the car’s agility and made the steering more responsive. Another pass added a torque overlay noticeable through the steering wheel during the initial avoidance maneuver that assisted in keeping the vehicle on the optimum trajectory, and yet another pass added the torque overlay for both emergency turns.

“This is a functionality we can do when one day we have sensor fusion, which means a camera together with the radar,” Hartmann explained. “When we have both, we will see not just the obstacle; we will also see the road. And when we see the road, we can give the driver support during steering in and then later in steering back to keep the vehicle on the road.”

The steering-wheel torque is set according to the automaker’s requirements, noted Dr. Peter Laier, Vice President of the Chassis Components business unit of the Chassis & Safety Division. “So we have the opportunity to set it in different rates…It’s a kind of OEM DNA. Like many safety technologies, the OEMs have different tastes in how they want to apply it.”

As we approached 80 km/h (50 mph) and above—beyond the limits of agility enhancement alone—Hartmann enabled an enhanced ESC setup and adaptive suspension for much improved stability. “I can switch a parameter in the ESC to be much more restrictive,” he explained. “Yaw response of the car has very, very high damping.”

Continental refers to ESA as a “support system” because it waits for driver intention and then provides a “recommendation” (i.e., additional steering torque). It does not operate automatically—yet.

“We start with a very robust specification where the driver is always in the loop and can always overrule the system,” said Hartmann. “Our vision is one day to have a highly automated system. Maybe in 20 years or so, the system takes over, but not at this stage.”

The technology is in the initial development stage now; the next step is series development and customer application. Production readiness is expected in two to three years.

ESA is most beneficial for highway driving; braking is more effective in city driving because vehicle speeds are lower. Continental offers Emergency Brake Assist City, which has been in series production for two years on the Volvo XC60, for such situations.

ESA adds to the portfolio of Continental’s ContiGuard integrated safety concept, on the path toward its ultimate goal of Vision Zero—road traffic with zero accidents and zero fatalities.

“When will we be at zero is for me just a matter of time,” said Dr. Ralf Cramer, Member of the Executive Board, Continental AG, and President of the Chassis & Safety Division. “Whether it is five years, 10 years, or 15 years, we’ll have to see.”

Cramer also believes the trend will continue toward smaller cars worldwide, which adds to the challenge of achieving zero fatalities. “What you need is not more metal; that makes the car heavier…What you need is more sensors and intelligent systems providing a safety shield.”

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