Abstract: In controlling valves, it is desirable for identical stroke changes to result in identical flow changes. To produce a non-linearity between the positioning signal and the valve opening, linearity is achieved between the positioning signal and the quantity of flow. In this case, the required positioning signal, in order to achieve a given opening stroke, is selected so that a linear function is produced between the quantity of flow and the positioning signal. The thus found setting signal is entered into the position regulator to control the valve. The position regulator is equipped for this purpose with a microprocessor circuit which acquires and processes the results of the ascertainment of the working characteristic of the installation.