Vehicle Stability Control System and Method

Abstract

A vehicle stability control system comprises a 5-sensor cluster and a stability controller configured to communicate with the 5-sensor cluster and receive signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate from the 5-sensor cluster. The stability controller can also be configured to determine a braking amount or a throttle amount to maintain vehicle stability. The system also comprises a brake controller configured to communicate with the stability controller and receive a braking request from the stability controller, and a throttle controller configured to communicate with the stability controller and receive a throttle request from the stability controller. The system may also comprise a braking or throttling command computed based on various scenarios detected by measured and calculated signals.

1 . A vehicle stability control system, comprising:
 a 5-sensor cluster;   a stability controller configured to communicate with the 5-sensor cluster and receive signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate from the 5-sensor cluster, the stability controller also configured to determine a braking amount or a throttle amount to maintain vehicle stability;   a brake controller configured to communicate with the stability controller and receive a braking request from the stability controller; and   a throttle controller configured to communicate with the stability controller and receive a throttle request from the stability controller.   
     
     
         2 . The vehicle stability control system of  claim 1 , wherein the stability controller is configured to receive signals corresponding to a sideslip angle, a vehicle longitudinal velocity, wheel speeds, a throttle input, a transmission status, and a brake status. 
     
     
         3 . The vehicle stability control system of  claim 2 , wherein the stability controller is configured to receive signals corresponding to a clutch status. 
     
     
         4 . The vehicle stability control system of  claim 2 , wherein the brake status includes a foot brake stratus and a parking brake status. 
     
     
         5 . The vehicle stability control system of  claim 1 , wherein the stability controller comprises a state estimator. 
     
     
         6 . The vehicle stability control system of  claim 1 , wherein the state estimator is configured to receive signals corresponding to the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate from the 5-sensor cluster. 
     
     
         7 . The vehicle stability control system of  claim 6 , wherein the state estimator is configured to determine road grade based on inputs from the 5-sensor cluster. 
     
     
         8 . The vehicle stability control system of  claim 7 , wherein the state estimator is configured to use the road grade to determine whether the vehicle's throttle or brakes should be activated via a throttle request or braking request, respectively. 
     
     
         9 . A method for performing hill hold control, the method comprising:
 receiving signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate;   calculating a vehicle pitch angle from the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate;   calculating a road grade from the vehicle pitch angle; and   determining whether to apply brakes of a vehicle based on the road grade, a vehicle speed or wheel speeds, a transmission status, a throttle input, and a brake status.   
     
     
         10 . The method of  claim 9 , wherein determining whether to apply brakes of the vehicle is based additionally on a sideslip angle. 
     
     
         11 . The method of  claim 9 , wherein determining whether to apply brakes of the vehicle is based additionally on a clutch status. 
     
     
         12 . The method of  claim 9 , further including applying brakes of the vehicle when appropriate until driver applies brakes or presses throttle when in gear. 
     
     
         13 . The method of  claim 9 , wherein the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate are received from a 5-sensor cluster. 
     
     
         14 . A method for maintaining a driver's intended speed of a vehicle during hill driving, the method comprising:
 receiving signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate;   calculating a vehicle pitch angle from the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate;   calculating a longitudinal velocity gradient from the vehicle pitch angle;   determining whether the longitudinal velocity gradient is substantially close to zero; and   changing a throttle input of the vehicle to change the vehicle's velocity if the longitudinal velocity gradient is not substantially close to zero.   
     
     
         15 . The method of  claim 14 , further comprising applying brakes of the vehicle to change the vehicle's velocity if the longitudinal velocity gradient is not substantially the same as a driver's intended speed. 
     
     
         16 . The method of  claim 14 , wherein the signals corresponding to the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate are received from a 5-sensor cluster. 
     
     
         17 . A method for maintaining a constant speed for a vehicle, the method comprising:
 receiving signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate;   calculating a vehicle pitch angle from the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate;   calculating a longitudinal velocity gradient from the vehicle pitch angle; and   maintaining the longitudinal velocity substantially at zero.   
     
     
         18 . The method of  claim 17 , wherein the longitudinal velocity gradient is maintained substantially at zero by changing a throttle input of the vehicle. 
     
     
         19 . The method of  claim 17 , wherein the longitudinal velocity gradient is maintained substantially at zero by applying brakes of the vehicle. 
     
     
         20 . The method of  claim 17 , wherein the signals corresponding to the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate are received from a 5-sensor cluster. 
     
     
         21 . The vehicle stability control system of  claim 1 , wherein the stability controller is configured to detect a vehicle sliding into a loss of control. 
     
     
         22 . A method for detecting a vehicle sliding into loss of control, the method comprising:
 receiving signals corresponding to a lateral acceleration, a longitudinal acceleration, a yaw rate, a roll rate, and a pitch rate;   calculating a vehicle pitch angle from the lateral acceleration, the longitudinal acceleration, the yaw rate, the roll rate, and the pitch rate;   calculating a longitudinal velocity gradient from the vehicle pitch angle;   calculating a signed longitudinal velocity based on the longitudinal velocity gradient;   calculating a sideslip angle;   comparing the magnitude of the sideslip angle with a first threshold indicative of the vehicle's motion trend;   comparing the magnitude of the longitudinal velocity gradient with a second threshold indicative of lateral motion of the vehicle.   
     
     
         23 . A vehicle stability control system for controlling a vehicle's sliding into loss of control, the system comprising:
 detecting the vehicle's sliding into loss of control by comparing the vehicle's longitudinal velocity gradient with a reference speed computed from wheel speed sensors inputs;   detecting a lateral velocity of the vehicle and a longitudinal velocity of the vehicle when vehicle sliding is detected;   calculating a sliding velocity vector of the vehicle from the lateral velocity of the vehicle and the longitudinal velocity of the vehicle;   braking the vehicle such that tire forces of the vehicle are aligned in a direction opposite the vehicle sliding velocity vector to remove a sliding energy of the vehicle.