Active Handling: The Second Generation

In the mid-1998 model year, Active Handling was introduced as an option on Corvette, making it one of the few sports cars in the world to offer such advanced stability control. Working in conjunction with a yaw rate sensor, lateral accelerometer and a variety of other sensors, the antilock braking system (ABS) and traction control system (TCS) (Active Handling) assists the driver in maintaining control under a variety of driving circumstances — whether on wet or dry road surfaces.

For 2001, Active Handling is now standard for all Corvettes, representing a tremendous performance value and a significant advance over the competition. In addition, the second generation of Active Handling has been significantly improved, with a more seamless operation and less intrusion under enthusiastic driving conditions. "Our first-generation Active Handling System was very good," states Dave Hill, Corvette Chief Engineer and Performance Car Vehicle Line Executive. "For 2001, our second-generation Active Handling System is even better," continues Hill. "The Corvette Team's commitment to continuous improvement has resulted in the industry's most sporting stability system."

Staying true to its performance heritage — and in contrast to the more intrusive systems of some competitors — the Corvette Team championed a calibration philosophy based on how Corvette drivers actually drive their cars; a system that would detract from the total Corvette driving experience was not an option. "We felt it was better to calibrate the system around our knowledge of what our customers are going to do, rather than a system that intervenes heavily and slows them down," explains Rizzo. "Our intent was to encourage Corvette drivers to keep the system on. We wanted our Active Handling System to work with the drivers in their driving, rather than against them."

The 2001 Corvette ABS/TCS/AH (Active Handling System) Improvements:

• The ABS/TCS/AH hydraulic modulator technology has changed from the Bosch 5.0 to the Bosch 5.3 modulator. The Bosch 5.3 modulator is reduced in size, transmits less noise, improves cold temperature (-20 degrees Celsius) pressure apply response for Active Handling, and weighs 1.24 kilograms (3.31 pounds) less than the Bosch 5.0, while still providing equivalent performance.

• The ABS/TCS/AH system now has dynamic rear proportioning which electronically proportions hydraulic pressure to the rear brakes to help prevent rear brake bias, or lockup. This software feature eliminates the need for the rear brake circuit proportioning valve, resulting in less assembly parts and fewer brake pipe connections.

• The master cylinder pressure sensor has been integrated into the Bosch 5.3 hydraulic modulator, resulting in fewer assembly parts and brake pipe connections.

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• The ABS/TCS/AH system has added vehicle sideslip angle rate control to its core software algorithm. Vehicle sideslip angle rate control enhances overall system performance during evasive handling maneuvers where the driver is slow to respond to the handling dynamics of the vehicle. Sophisticated calibration algorithms are used to alter vehicle sideslip-angle rate control, based on whether the driver is "ahead" or "behind" the handling dynamics of the vehicle.

• Sophisticated calibration algorithms are used to estimate the friction coefficient of the road surface in order to optimize the vehicle sideslip-angle rate control. Vehicle sideslip angle rate control is magnified for slippery road surfaces, helping the driver to maintain control when road conditions are less than ideal.

• The ABS/TCS/AH system has added a rear brake stability control software feature to assist the driver in maintaining the desired vehicle path during light braking and high lateral acceleration vehicle conditions, such as might be encountered on an exit ramp. The rear brake stability control feature precisely releases the brake pressure on the inside rear wheel during high lateral acceleration vehicle conditions which results in a more predictable vehicle response and requires less work from the driver to keep the vehicle on the driver's intended path. The rear brake stability control feature functions separately from the normal ABS.

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• Competitive mode may now be accessed while driving by holding down the traction control button for five seconds, without having to stop the vehicle. Competitive mode deactivates the traction control system, which may be desirable in autocrosses or other racing events.

Taken as a whole, the new Active Handling System for the 2001 Corvette is smarter, less intrusive, and more adept at making the total driving experience precisely what Corvette owners have come to expect of their cars.

2001 Corvette Active Handling Schematic