Abstract: A tool spindle is driven by a motor and is connected to an angle of rotation transmitter. The signal of the transmitter connected to the tool spindle represents the desired value for the drive of a work piece spindle. The angle of rotation of the workpiece spindle is measured with another transmitter. A control deviation signal which is fed into a servo amplifier of the workpiece spindle drive via a controller is formed from both transmitter signals. A variable observer circuit into which the control deviation signal is also fed is arranged in parallel to the controller. The control deviation signal is stored sequentially in several sample and hold circuits by means of a multiplexer circuit during one tool revolution. The content of each sample and hold circuit is integrated by means of a respective integrator. During the following cycle, a correction signal, which is added to the output signal of the controller, is formed by sequential interrogation of the integrators by means of a demultiplexer circuit.