Determination of a correcting variable for controlling a moment regulator in a vehicle steering system

1. A method for determining an actuating variable for actuating a torque control element in an electric vehicle steering system as a function of a predefined target torsion-bar torque (MD, ref), comprising:

detecting an actual torsion-bar torque (MD);

deriving a differential torque from the predefined target torsion-bar torque (MD,ref) and the actual torsion-bar torque (MD); and

determining the actuating variable with an output feedback controller based on a function of the differential torque.

2. A method according to claim 1 , wherein the actual torsion-bar torque (MD) is filtered, and instead of the actual torsion-bar torque (MD), the filtered actual torsion-bar torque (MD) is used to find the differential torque.

3. A method according to claim 1 , wherein the target torsion-bar torque (MD,ref) is filtered, and instead of the target torsion-bar torque (MD,ref), the filtered target torsion-bar torque (MD,ref) is used to find the differential torque.

4. A method according to claim 1 , wherein the actual torsion-bar torque (MD) and the target torsion-bar torque (MD,ref) are fed to the output feedback controller, and the differential torque is generated in the output feedback controller.

5. A method according to claim 1 , wherein the actuating variable is additionally determined as a function of a current actuating variable.

6. A control device for controlling a steering system in a vehicle, the steering system comprising a torque control element, and the control device comprising means for actuating the torque control element by way of an actuating signal, and means for determining the actuating signal as a function of a predefined target torsion-bar torque (MD,ref), wherein the control device comprises means for finding a differential torque from the target torsion-bar torque (MD,ref) and an actual torsion-bar torque (MD); and an output feedback controller is provided in the control device, with an actuating variable being determined by means of the output feedback controller as a function of the differential torque.

7. A control device according to claim 6 , wherein a filter element for filtering the actual torsion-bar torque (MD) is provided in the control device, and the control device comprises means for finding the differential torque from the filtered actual torsion-bar torque (MD), instead of the actual torsion-bar torque (MD).

8. A control device according to claim 6 , wherein a filter element for filtering the target torsion-bar torque (MD,ref) is provided in the control device, and the control device comprises means for finding the differential torque from the filtered target torsion-bar torque (MD,ref), instead of the target torsion-bar torque (MD,ref).

9. A control device according to claim 6 , wherein the output feedback controller comprises means for finding the differential torque.

10. A control device according to claim 6 , wherein the actuating variable can additionally be determined as a function of a current actuating variable.

11. A non-transient computer-readable medium having a computer program product which can be executed on a control device for controlling a steering system, the control device comprising a microprocessor configured for executing the computer program product, wherein the computer program product programs the control device to carry out the method according to claim 1 .

12. A non-transient computer-readable medium according to claim 11 , wherein the computer program product is stored on a memory element.