Method for controlling a motor vehicle in emergency steering mode by means of front wheel brake-based torque vectoring

A method for controlling a steer-by-wire steering system for a motor vehicle in an emergency steering mode, wherein the motor vehicle comprises two axles each with two wheels, wherein the two front wheels are steerable with a front-wheel steering system and are connected to one another via a steering tie rod of a steering system of the front-wheel steering system, wherein the motor vehicle comprises a single wheel drive that is assigned to one of the two axles and that drives the two wheels of the one axle via a differential, wherein the single wheel drive comprises a single actuator, wherein the motor vehicle comprises a brake system, the method comprising:

• checking the steering system for the presence of a fault state;
• and
• implementing an emergency steering mode upon detection of a fault state, wherein the following steps are performed in the emergency steering mode:
• determining a setpoint position of the steering tie rod using a setpoint wheel steering angle,
• determining a front wheel to be braked and a brake pressure to attain the setpoint position with a control unit,
• transmitting the front wheel to be braked and the brake pressure to the brake system,
• braking the front wheel to be braked, and
• increasing a torque provided by the single wheel drive to compensate for a loss of speed of the motor vehicle caused by the braking of the front wheel to be braked;
• wherein the single wheel drive is a front-wheel drive with an open differential, wherein the method comprises in the emergency steering mode driving with the front-wheel drive a non-braked front wheel such that a sum of torques of the two front wheels and the increased torque compensating for the loss of speed of the motor vehicle;
• wherein the following applies while the motor vehicle travels through a right-hand bend:
• TFL+TFR=2*TFL+Tped,br,
• wherein TFL is a torque of a left-hand front wheel,
• wherein TFR is a torque of a right-hand front wheel,
• wherein Tped,br is a braking torque introduced into the front wheel to be braked.