Wheel grip factor estimation apparatus

A vehicle motion control apparatus having an apparatus for estimating a grip factor of a vehicle wheel comprising:

• steering factor detection means for detecting at least one of steering factors including a steering torque and steering effort applied to a steering system from a steering wheel to a suspension of said vehicle;
• aligning torque estimation means for estimating an aligning torque produced on at least a wheel of said vehicle on the basis of the steering factor detected by said steering factor detection means;
• vehicle state variable detection means for detecting a state variable of said vehicle;
• wheel factor estimation means for estimating at least one of wheel factors including a side force and slip angle applied to said wheel on the basis of the state variable detected by said vehicle state variable detection means;
• and
• grip factor estimation means for estimating a grip factor of at least a tire of said wheel, in accordance with a relationship between the aligning torque estimated by said aligning torque estimation means and the wheel factor estimated by said wheel factor estimation means, and
• said vehicle motion control apparatus further comprising;
• control means for controlling at least one of braking force, engine output and shift position of said vehicle at least in response to the state variable detected by said vehicle state variable detection means, said control means controlling at least one of the braking force, engine output and shift position of said vehicle when the grip factor estimated by said grip factor estimation means becomes less than a predetermined value, to reduce a speed of said vehicle.