Quadrant based friction compensation for tire load estimation in steering systems

A method to estimate a tire load in a steering system, the method comprising:

• receiving, as an input torque, motor-torque that is generated by a motor of the steering system;
• computing an efficiency factor for a gear of the steering system based on the input torque and an angular motor velocity;
• adjusting the input torque by scaling the input torque with the efficiency factor;
• and
• estimating the tire load based on the adjusted input torque.

A steering system comprising:

• a steering gear;
• a processor configured to compute a tire load estimate by performing a method comprising:
• receiving, as an input torque, motor-torque that is generated by a motor of the steering system;
• computing an efficiency factor for a gear of the steering system based on the input torque and an angular motor velocity;
• adjusting the input torque by scaling the input torque with the efficiency factor;
• and
• estimating the tire load based on the adjusted input torque.