GM Leads the Way in Vehicle Stability Enhancement Systems
FOR RELEASE: May 9, 2002GM Leads the Way in Vehicle Stability Enhancement Systems
Detroit, Mich. - General Motors leads the industry in bringing the safety advantages of vehicle stability enhancement systems to more people in more market segments.
Since the introduction of StabiliTrak on three 1997 Cadillac models, GM has continued to refine its stability enhancement systems and expand them to other model lines. Overall, GM has nearly 1 million vehicles equipped with stability enhancement systems on the road today. GM's stability enhancement systems are known as StabiliTrak, Precision Control System and Active Handling.
The system has been added to GM's full-size sport utility lineup for 2003. The new four-channel StabiliTrak in these vehicles operate with the antilock brake and traction control systems to selectively apply any of the four brakes to help the driver counteract and diffuse potentially dangerous handling situations, such as severe oversteer or understeer.
Stability enhancement helps a driver maintain control of the vehicle, a key factor in crash-avoidance. While loss of control is most likely to happen on ice, snow, wet pavement or gravel roads, these systems help improve stability on a variety of surfaces and speeds, as well as in emergency lane changes or avoidance maneuvers.
As impressive as these systems are, it is important to remember that they cannot override physics. There will be circumstances in which this technology will not be able to overcome gross driver error or other road hazards.
Today's stability enhancement systems are the result of an ongoing evolution in chassis controls at GM that began with the introduction of antilock braking systems (ABS) on the 1986 Corvette. The evolution continued with innovations such as electronic traction control, electronic throttle controls, variable assist steering and variable suspension systems.
The integration of these chassis systems enabled GM to create its first stability enhancement system, StabiliTrak, by adding two additional sensors - measuring yaw rate and lateral acceleration - along with an updated steering angle sensor and new software.
With a vehicle stability enhancement system, a digital steering-angle sensor precisely measures the driver's intended path. The yaw of the vehicle body - the rate at which it is actually turning - is measured by a solid-state yaw rate sensor that uses a pair of tiny ceramic tuning forks to convert the turning motion of the body into a signal the computer can read.
A third sensor, which measures lateral acceleration, helps the computer determine whether available traction has been exceeded. Information is also gathered on vehicle speed. This allows the computer to fine-tune corrections to match the cornering speeds and available traction.
The same computer that operates the anti-lock brakes and traction control system also operates the stability enhancement system. Using these various inputs, the system compares the driver's intended path with the vehicle's actual path, and adjusts the brake and throttle to help bring the vehicle back under control.
Real-world maneuvers, such as an emergency lane change, may involve several quick steering inputs. Throughout these maneuvers, the stability enhancement system calculates the desired direction of travel and adjusts the individual brakes and throttle in fractions of a second to optimize stability and control.
The system also enhances the stability of the vehicle where the yaw rate of the vehicle doesn't correspond with the steering inputs from the driver. If the vehicle starts to skid because of snow, ice, gravel or standing water, the onboard computer gently applies the correct corner brake to maintain the driver's intended path. If the driver enters a corner or off-ramp too quickly, the system helps the driver bring the vehicle under control.
General Motors , the world's largest vehicle manufacturer, designs, builds and markets cars and trucks worldwide. In 2001, GM earned $1.5 billion on sales of $177.3 billion, excluding special items. It employs about 362,000 people globally.
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Stability Enhancement System: Fact sheet
What is a stability enhancement system?
GM's vehicle stability enhancement systems (VSES) improve vehicle stability on a variety of road surfaces, particularly on slick surfaces or during emergency maneuvers. The system maximizes handling and braking dynamics by using a combination of software and sensors, including ABS, traction control and electronic powertrain controls.
How do these systems work?
An array of sensors continually monitor the driver's intended vehicle path, measuring steering angle, wheel speed, brake pressure, lateral acceleration, longitudinal acceleration and yaw rate. This information is provided to an electronic control module that continually monitors vehicle dynamics and is programmed for intervention thresholds. The system intervenes when it senses one or more of the wheels slipping, loss of lateral traction (side slip), or detects understeer (snow-plowing) or oversteer (fish-tailing). Automatically, the system adjusts engine torque or brake pressure to help to steer the vehicle in the intended path, as determined by the driver's steering inputs.
In what type of situations does the stability enhancement system become active?
It helps control or minimizes fishtailing on snowy or wet roads, improving stability and handling. The system assists the driver in maintaining control while cornering on wet roads or uneven road surfaces, such as puddles or snow piles. It also helps the vehicle respond more naturally and predictably to the driver's steering commands, even in avoidance maneuvers.
Which GM vehicles are equipped with StabiliTrak, Precision Control or Active Handling?
GM offers stability enhancement systems on 11 2002 model year North American products. By the 2006 model year, this feature will be available on many more of the vehicles in our portfolio.
For 2002, GM offers stability enhancement systems in the following segments:
- Performance: Chevrolet Corvette (Active Handling)
- Family sedan: Oldsmobile Intrigue (Precision Control System)
- Large sedan: Pontiac Bonneville (StabiliTrak), Oldsmobile Aurora (Precision Control System), Buick LeSabre (StabiliTrak), Buick Park Avenue (StabiliTrak)
- Luxury coupe: Cadillac Eldorado (StabiliTrak)
- Luxury sedan: Cadillac DeVille (StabiliTrak), Cadillac Seville (StabiliTrak)
- Luxury SUV: Cadillac Escalade (StabiliTrak)
- Luxury sport-utility truck: Cadillac Escalade EXT (StabiliTrak)
- New for '03 Full-Size Sport Utility Vehicles,
- Utility Truck: Chevrolet Tahoe, Suburban, Avalanche, GMC Yukon, Yukon XL, Yukon Denali and Yukon Denali XL (all 1500 series)
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