Drive slip control system

Drive slip control system for a vehicle having an engine which transmits torque to the driven wheels through a transmission having a plurality of gear ratios, said system comprising

• wheel speed sensors for determining speeds of the driven wheels and generating sensed wheel speed signals corresponding to the determined speeds,
• means for determining actual accelerations of the driven wheels from the sensed wheel speed signals and generating actual wheel acceleration signals,
• means for determining an average wheel speed of the driven wheels from said sensed wheel speed signals,
• means for determining engine speed,
• means for generating an actual quotient from the average wheel speed and the engine speed,
• means for determining and storing a plurality of constant values based on respective gear ratios,
• means for comparing the actual quotient to the closest constant value and generating an output signal corresponding to said closest constant value when a prescribed deviation between said actual quotient and said closest constant value is exceeded,
• means for generating a reference wheel speed signal from said output signal corresponding to said closest constant value and said engine speed,
• means for generating a reference wheel acceleration signal from said reference wheel speed signal, and
• evaluation circuit means which receives said actual wheel acceleration signals and said reference wheel acceleration signal, limits the actual wheel acceleration signals by the reference wheel acceleration signal, determines slippage of said driven wheels from the actual wheel acceleration signals, and generates control signals for at least one of braking at least one of said driven wheels and decreasing the engine torque when slippage is determined.