Abstract: A method for controlling/regulating a rotatory drive of a working unit of a track maintenance machine includes using a sensor to record a measurement parameter with an approximately periodic history function derived from a rotation of the drive. A frequency or period duration of the history function is determined with an evaluation device, and the frequency or period duration is compared with a target parameter for stipulating a control signal. A number of time-discrete measurement values is formed for the measurement parameter and an auto-correlation of these measurement values is carried out by a calculation unit for determining the frequency or the period duration. As compared to a conventional method with zero stage recording, a precise recording of frequency changes is therefore also possible between two zero stages. A device for carrying out the method is also provided.