Based on the curvature information for an upcoming road, an automatic speed control system regulates vehicle speed to improve vehicle curve following performance. The road information is extracted from a digitally stored map using the current vehicle position obtained from Global Positioning System (GPS) data. Then, a safe curve speed is determined using the lateral dynamics of vehicle in turn to ensure proper curve handling. Other factors, such as vehicle characteristics, driver preferences, and road and environment conditions are also considered so that vehicle safety and driver comfort are enhanced. An acceleration command is generated from the current vehicle speed and the desired curve speed profile. Driving mode, such as conservative, normal, or aggressive mode, can be selected from the console for a desired driving style. The gain and preview time to determine the vehicle cornering speed are selected according to driver’s preference. The functional blocks of the system include computation of the road curvature, determination of a desired curve speed profile for the best cornering performance for an upcoming curve, and regulation of vehicle speed toward the desired speed. Signal input blocks and actuator control blocks are added to interface with the bus oriented sensors and actuators. The entrance and exit conditions block checks for various vehicle status signals to enter or exit the curve speed control mode gracefully. It also generates a diagnostic message when map data is absent or an error occurs on acceleration command computation. The vehicle studies indicated that the curve speed control system is effective in regulating vehicle speed during curve following maneuvers.

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