Method and apparatus to regulate illumination range of a motor vehicle

Method to regulate an illumination range of a motor vehicle in which signals are measured from a position on a front axle and a position on a rear axle which depend upon a relative position of a motor-vehicle body to the front axle and the rear axle, with a difference signal formation between the signal of the front axle and that of the rear axle being accomplished, the resulting difference signal, as a nominal-value signal, being filtered to a first, average, nominal value, whereby a time for development of the first, average, nominal value is determined by a first filter time constant, with portions of adjusting elements being thereby regulated when the first, filtered, nominal value deviates from a predetermined set value, wherein the improvement that:

• simultaneously with formation of the first, average, nominal value, producing a second average value of the nominal-value signal with a second, short, filter time constant and a third average value of the nominal-value signal with a third, long, filter time constant;
• comparing the thusly-produced second, filtered, nominal-value signal with the thusly-produced third, filtered, nominal-value signal;
• and, upon the presence of a difference between the second, filtered, nominal-value signal and the third, filtered, nominal-value signal, switching the regulation from the first, filtered, nominal-value signal over to the third, filtered, nominal-value signal and, upon a termination of said difference, gain switching regulation over from the third, filtered, nominal-value signal to the first, filtered, nominal-value signal.