| 摘要 |
A method and apparatus for adapting powertrain braking to mass, grade, and brake temperature. Vehicle mass is determined using a vehicle speed sensor and an tractive effort model based on engine-torque delivered, torque converter multiplications, and transmission ratio and tire rolling radius effects. Road grade is continuously calculated and altitude change is calculated based on grade and distance traveled. To achieve an ideal amount of powertrain braking, powertrain braking is directed towards a designed coast performance target based on deceleration as a function of vehicle speed. Fuzzy logic is used to evaluate driver intentions, grade load conditions, terrain conditions, brake conditions and other vehicle information to determine the actual, optimal powertrain braking control. A real time brake thermal model is developed to provide increased powertrain under extreme brake conditions. The powertrain braking efforts are limited when restricted by available tractive efforts. |
