Abstract: A method of operating an electric power steering system installed on a vehicle. The electric power steering system includes a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to an electric motor. The method includes the step of controlling the electric motor to achieve a nominal value of power steering assist torque when the electrical power available to the motor is sufficient to achieve the nominal value of power steering assist torque. The method further includes the step of controlling the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the electrical power available to the motor is not sufficient to achieve the nominal value of power steering assist torque.

Abstract: A method of operating an electric power steering system installed on a vehicle. The electric power steering system includes a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to an electric motor. The method includes the step of controlling the electric motor to achieve a nominal value of power steering assist torque when the electrical power available to the motor is sufficient to achieve the nominal value of power steering assist torque. The method further includes the step of controlling the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the electrical power available to the motor is not sufficient to achieve the nominal value of power steering assist torque.

Abstract: A steering system for an autonomously driven vehicle and methods of steering the vehicle are disclosed. A main controller signals a secondary steering assembly to operate in a first phase when a power steering controller is in a first mode and a second phase to steer the vehicle when the power steering controller is in a second mode. The main controller signals a friction device to actuate to a disengaged position when the power steering controller is in the first mode and the secondary steering assembly is in the first phase, and to signal the friction device to actuate to an engaged position to secure a steering wheel in an initial position when the power steering controller is in the second mode and the secondary steering assembly is in the second phase to allow the secondary steering assembly to steer the vehicle.

Abstract: A steering system for an autonomously driven vehicle and methods of steering the vehicle are disclosed. A main controller signals a secondary steering assembly to operate in a first phase when a power steering controller is in a first mode and a second phase to steer the vehicle when the power steering controller is in a second mode. The main controller signals a friction device to actuate to a disengaged position when the power steering controller is in the first mode and the secondary steering assembly is in the first phase, and to signal the friction device to actuate to an engaged position to secure a steering wheel in an initial position when the power steering controller is in the second mode and the secondary steering assembly is in the second phase to allow the secondary steering assembly to steer the vehicle.

Abstract: A steering system for an autonomously driven vehicle and methods of steering the vehicle are disclosed. A brake device is operable in a first phase to brake the vehicle when a power steering controller is in a first mode and operable in a second phase to steer the vehicle when the power steering controller is in a second mode. A main controller is in communication with a friction device to signal the friction device to actuate to a disengaged position when the power steering controller is in the first mode and the brake device is in the first phase, and signal the friction device to actuate to an engaged position to secure a steering wheel in an initial position when the power steering controller is in the second mode and the brake device is in the second phase to allow the brake device to steer the vehicle.

Abstract: A method for improving a failure mode diagnostic of an electric power steering system by overcoming a motor electric lock condition due to position sensor signal corruption or other motor faults. If certain conditions are met, the method determines that the motor is in an electric lock condition, and then reduces a torque current command to the motor so that it is able to be rotated by a vehicle hand-wheel. Once the motor is able to be rotated, then the method determines whether certain conditions have been met to determine whether the position sensor is malfunctioning.

Abstract: A method for improving a failure mode diagnostic of an electric power steering system by overcoming a motor electric lock condition due to position sensor signal corruption or other motor faults. If certain conditions are met, the method determines that the motor is in an electric lock condition, and then reduces a torque current command to the motor so that it is able to be rotated by a vehicle hand-wheel. Once the motor is able to be rotated, then the method determines whether certain conditions have been met to determine whether the position sensor is malfunctioning.