Traction control system using estimated road surface friction coefficient

A traction control system for a motor vehicle, having driving wheels and driven wheels, comprising:

• means for detecting a speed of each of the driving wheels of the vehicle and calculating an acceleration of the driving wheels;
• means for detecting a speed of each of the driven wheels of the vehicle and calculating an acceleration of the driven wheels;
• means for detecting an engine output;
• means for calculating a slip value of the driving wheels based on the speeds of the driving and driven wheels detected;
• traction control means for controlling the driving wheels so that the slip value of the driving wheels is equal to a predetermined desired slip value when the slip value of the driving wheels is greater than a predetermined slip value for starting a traction control operation;
• and
• means for estimating a friction coefficient of a road surface which is employed when the predetermined desired slip value is determined, said friction coefficient estimating means estimating the friction coefficient of the road surface based on the engine output only when the speeds of the driven wheels are not greater than a predetermined value and the acceleration of the driving wheels is greater than a predetermined value, said friction coefficient estimating means estimating the friction coefficient of the road surface based on the acceleration of the driven wheels when the speeds of the driven wheels are greater than the predetermined value.

A traction control system for a motor vehicle, having driving wheels and driven wheels, said vehicle having an auotmatic transmission with a torque converter by which an engine output is transmitted to the driving wheels, said system comprising:

• means for detecting a speed of each of the driving wheels of the vehicle and calculating an acceleration of the driving wheels;
• means for detecting a speed of each of the driven wheels of the vehicle;
• means for detecting an engine speed;
• means for calculating a slip value of the driving wheels based on the speeds of the driving and driven wheels detected;
• traction control means for controlling the driving wheels so that the slip value of the driving wheels is equal to a predetermined desired slip value when the slip value of the driving wheels is greater than a predetermined slip value for starting a traction control operation;
• and
• means for estimating a friction coefficient of a road surface which is employed when the predetermined desired slip value is determined, said friction coefficient estimating means estimating the friction coefficient of the road surface based on the engine speed only when the vehicle is starting and the acceleration of the driving wheels is greater than a predetermined value.