A motor vehicle power steering mechanism with an electric motor for steering assist and/or steering, and a steering controller, which controls the electric motor with a position control mode for autonomous driving and/or automatic steering and a torque control mode for manual steering by a driver. The steering controller includes a steering column reference controller, an arbitration unit, a column torque controller, a steering algorithm, and the steering system. The steering column reference controller calculates for position control based on a reference position and a measured position, and a first reference steering column torque. A steering algorithm calculates for torque control based on a measured column torque and a second reference steering column torque. The arbitration unit weights and adds the first and second reference steering column torques, and the output of the arbitration unit is input to the column torque controller.