ASR - Traction Control - A Logical Extension of ABS 870337
Control of a car is lost, or considerably reduced, whenever one or more of the wheels exceed the stability limit during braking or accelerating due to excessive brake or drive slip.
The problem of ensuring optimum stability, steerability and brake distance of a car during hard braking is solved by means of the well-known Anti-lock Braking System (ABS). The task to guarantee stability, steerability and optimum traction during acceleration, particularly on asymmetrical road surfaces and during cornering maneuvers, is being performed by the traction control system (ASR).
Several means to provide an optimum traction control are described, e. g the control of engine torque by influencing the throttle plate and/or the ignition and/or the fuel injection. Besides these means serving mainly the car's stability, means for the optimization of the traction, especially on split u surfaces, through brake-force control of the driven wheels or through a variable limited-slip differential are explained.
Closed-loop control of the engine drag torque (MSR) is an advantageous addition to ABS in order to guarantee stability and steerability, especially on cars with manual transmissions.
Several ASR-system configurations are described and evaluated.