Steering method for an autonomously steered vehicle

A servo-assisted steering assembly for an autonomously steered vehicle having a hybrid steering system, comprising

• at least one hydraulic servo valve that functions as a hydraulic steering assistance system and includes an actuator for controlling the steering assistance system in dependence upon a relative rotation of an input shaft with respect to an output shaft;
• at least one electromechanical steering assistance system that functions as a superimposed steering system, wherein the superimposed steering system boosts the supporting steering torque in response to a boost curve;
• and
• a control unit for monitoring and controlling the driving procedure of the vehicle;
• wherein the control unit is configured so that upon recognizing a malfunction during an autonomous driving procedure the steering task is switched to a steering braking procedure, and
• wherein the servo-assisted steering assembly is coordinated so that frictional torques that occur above the hydraulic servo valve do not have any influence on the hydraulic pressures that are acting in the chambers of the hydraulic steering assistance and consequently do not subject the steering braking procedure to a counter torque.