Abstract: A control unit (75) for controlling a first state variable of a system, for example an angle of rotation .phi. of a throttle valve (7) in a throttle device for use in an internal-combustion engine, the system being influenced by a disturbance variable during operation, for example an oscillating loading torque caused by air-flow fluctuations in the throttle device. The control unit includes a disturbance observer (125) for calculating a value of the disturbance variable at a first point in time on the basis of a mathematical model of the system, and a disturbance predictor (128) for predicting a value of the disturbance variable at a second point in time which follows the first point in time by a predetermined time interval. In this manner, a phase shift between the disturbance variable actually influencing the system and the compensation provided by the system for the disturbance variable is prevented at high frequencies of the disturbance variable.