Patent ID: 7199541

Claim:
A method of controlling an electric motor with oscillating output shaft, for automobile wiper systems, characterized in that the output shaft of the motor swings first to one end stop, the direction of the rotation of the motor then changes, whereupon the output shaft is returned at a constant speed to the opposite stop, whilst in the same pre-selected constant time intervals its angular position is measured between the two stops; taking into account the size of the angle between the two stops, the measurement data on the angular position are converted into angle increments in individual, measured, constant time intervals, from which a calibration curve is made of the sensor used for measuring the angular position of the output shaft of the motor and from this calibration curve is then determined the absolute value of the output variable of the sensor used, for any angle of the actual position of the output shaft of the motor, whereupon the required time behaviour behavior of the angular position of the electric motor is determined, and then continuously at certain time intervals depending upon the required number of swings per time unit, data on the angular position of the output shaft of the motor are taken, in accordance with the calibration curve the data are converted into the actual angular value of the position of the output shaft, and if a deviation is discovered from the required time behavior at any given moment, a correction is made in the speed of the electric motor depending upon the direction and magnitude of this deviation.