A New Slip Controller to Reduce Braking Distance by Means of Active Shock Absorbers

This paper presents a control algorithm for semi-active suspensions to reduce the braking distance of passenger cars. Active shock absorbers are controlled and used to influence the vertical dynamics during ABS-controlled full braking.

The core of the approach presented in this paper is based on a switching control logic which sets the car's body damping to one of the two extrema hard and soft. The control algorithm is implemented in a compact class passenger car. Test drives on a real road, using a braking machine for reproducibility reasons, have been executed.

It could be shown that it is possible to reduce the braking distance by affecting on the vertical dynamics of a passenger car in general. This is the first published experimental result of its kind. The amount of reduction depends on the height profile of the testing track. On a road with an unevenness comparable to the one on a typical German Autobahn a reduction of typically 1.3 %, compared to the best passive damping, was achieved. On a very rough road, the average braking distance was reduced by 3.5 %, compared to the best passive damping.