Vehicle systems control for improving stability
Improved methods of controlling the stability of a vehicle are provided via the cooperative operation of vehicle stability control systems such as an Active Yaw Control system, Antilock Braking System, and Traction Control System. These methods use recognition of road surface information including the road friction coefficient (mu), wheel slippage, and yaw deviations. The methods then modify the settings of the active damping system and/or the distribution of drive torque, as necessary, to increase/reduce damping in the suspension and shift torque application at the wheels, thus preventing a significant shift of load in the vehicle and/or improving vehicle drivability and comfort. The adjustments of the active damping system or torque distribution temporarily override any characteristics that were pre-selected by the driver.
1. A cooperative Active Damping System (ADS) method for providing enhanced stability of a vehicle travelling on a road, comprising the steps of:
providing an Active Damping System (ADS) for adjusting suspension characteristics on the vehicle;
providing an Antilock Braking System (ABS) on the vehicle;
providing a Traction Control System (TCS) on the vehicle;
providing an Active Yaw Control (AYC) system on the vehicle;
inferring a high coefficient of friction of the road surface when an operational (Activating/Not activating) status of at least one of the TCS and AYC systems is “Activating” and a vector representation of the vehicle's longitudinal and lateral acceleration is greater than 0.5 g, and inferring a low coefficient of friction of the road surface when the operational status of at least one of the TCS and AYC systems is “Activating” and the vector representation of acceleration is below 0.3 g; and
upon inferring a high coefficient of road surface friction, adjusting a damping state of the ADS to a high damping setting; and
upon inferring a low coefficient of road surface friction, adjusting the damping state of the ADS to a low damping setting.
2. The method of claim 1 , wherein after a fixed period of time of between 1 and 3 seconds, returning the ADS to a damping state prior to inferring road conditions.
3. The method of claim 1 , wherein the adjustments to the damping state of the ADS override a driver pre-selected damping state of the ADS.
4. The method of claim 1 , wherein the ADS includes electronically controlled, fast-acting Magneto-Rheological fluid dampers.
5. A method for providing enhanced vehicle stability comprising the steps of:
providing a vehicle with all wheel drive;
providing a Vehicle Stability Assist (VSA) system on the vehicle;
providing a Traction Control system (TCS) on the vehicle;
providing an Active Yaw Control (AYC) system on the vehicle;
inferring a high coefficient of friction of a road surface when an operational (Activating/Not activating) status of at least one of the TCS and AYC systems is On and a vector representation of the vehicle's longitudinal and lateral acceleration is greater than 0.5 g and inferring a low coefficient of friction of the road surface when the operational status of each of the TCS and AYC systems is “Activating” and the vector representation of acceleration is below 0.3 g; and
upon inferring the coefficient of friction of the road, changing thea distribution of torque amongst vehicle wheels as follows:
if the coefficient of friction is high, implementing a strong side to side and front to rear torque bias; and
if the coefficient of friction is low, implementing a moderate side to side and front to rear torque bias.
6. The method of claim 5 , wherein after a fixed period of time between 1 and 3 seconds, returning the distribution of drive torque to a state prior to inferring road conditions.
7. The method of claim 5 , wherein changes to the distribution of drive torque overrides any driver pre-selected distribution of drive torque.