Friction estimation for steering maneuvers for stationary or slow-rolling automobiles

A device for estimating a friction coefficient between a road surface and an automotive tire through determination of a steering torque during a steering maneuver of a slow-rolling or stationary vehicle, comprising:

• a computer configured for constructing a brush model for a description of the steering torque across a contact patch between the automotive tire and road surface, the steering torque being a torque acting on a steering axis required to overcome resistance to tire twisting on the road surface at a wheel velocity and a steering rate, the steering torque depending on a tire brush vertical load distribution and relative motion of tire brushes on the tire and the road surface;
• sensors for measuring the wheel velocity and the steering rate;
• and
• mechanism for measurements or estimation of the steering torque;
• the computer further adapted for estimating the friction coefficient based on the measurements or estimation of the steering torque and the brush model;
• wherein the wheel velocity is not greater than a predetermined value.