Servotwin® electrohydraulic steering system

The Servotwin® – more steering comfort and driver assistance functions

The Servotwin® electro-hydraulic steering system for automated driving consists of the proven RB-Servocom® ball-and-nut power steering system and a platform-based combination of electric motor with control unit and worm gear transmission. The recirculating ball gear power steering system provides most of the steering assistance. Its design is based on the principle employed in a classic hydraulic power steering system. An oil circuit and a power cylinder provide the hydraulic steering assistance for the steering wheel motions of the driver. Using an electric motor and worm gear, an additional turning moment can be applied to the input shaft of the RB-Servocom® in parallel to the steering wheel's moment. In this way, the manual force needed for steering can be varied depending on the driving situation. The mechanical connection from the steering wheel to the steering linkage is preserved. A turning motion of the steering wheel and the applied steering moment are sensed by turning angle and torque sensors and transmitted to the integrated electronic control unit (ECU).