Patent ID: 8560178

Claim:
A system for providing steering torque assistance to an electrically-powered steering apparatus of a vehicle, the system comprising: one or more safety sensors; a torque assistance motor coupled to the electrically-powered steering apparatus; and a steering controller in communication with the torque assistance motor; the steering controller being configured to cause the torque assistance motor to apply a commanded level of steering torque assistance to the electrically-powered steering apparatus; the torque assistance motor being positioned and configured so as to apply the commanded level of steering torque assistance to the electrically-powered steering apparatus in response to commands from the steering controller; the one or more safety sensors positioned and configured so as to provide a feedback signal to the steering controller, the feedback signal being indicative of a safety parameter associated with the electrically-powered steering apparatus or the torque assistance motor; the steering controller being configured to determine the commanded level of steering torque assistance based on a product of a scheduled level of steering torque assistance and a torque assistance scale factor; the scheduled level of steering torque assistance being determined from a scheduled torque assistance characteristic having a nominal assist; the steering controller being configured to determine a scaled assist based on the feedback signal, the scaled assist configured for respecting a predefined system limitation; and the torque assistance scale factor being determined as a ratio of the scaled assist and the nominal assist.