BACKUP CONTROL OF ELECTRIC POWER STEERING SYSTEM WHEN SENSOR FAILURE OCCURS

Systems and methods for controlling an electric power steering system. The system includes an electric motor configured to provide a torque to a steering mechanism of a vehicle, a torsion bar torque sensor, a vehicle speed sensor, and a steering angle sensor. The system also includes an electronic controller configured to determine a failure of the torsion bar torque sensor, receive a vehicle speed from the vehicle speed sensor and a steering angle from the steering angle sensor, calculate a steering assistance torque based on the vehicle speed and the steering angle, calculate a hysteresis torque based on the steering angle, sum the steering assistance torque and the hysteresis torque to determine a turning torque, calculate a return torque and sum the turning torque and return torque to obtain an output torque, and generate a command for the electric motor to provide the output torque to the steering mechanism.