Patent ID: 7502676

Claim:
A tire grip level estimation apparatus comprising: self-aligning torque acquisition means which estimates or detects self-aligning torque generated on the grounding surface of wheels; lateral direction quantity-of-state computation means which computes lateral direction quantity of state generated in said wheels; front-rear direction quantity-of-state computation means which computes front-rear direction quantity of state generated in said wheels; self-aligning model value computation means which computes self-aligning torque model value on the basis of said lateral direction quantity of state and one or more tire parameters; ratio computation means which computes self-aligning ratio, which is the ratio between the self-aligning torque estimated or detected by said self-aligning torque acquisition means and the self-aligning torque model value computed by said self-aligning model value computation means; and grip level estimation means which estimates a grip level of the tires on the basis of said self-aligning ratio and said front-rear direction quantity of state from a predetermined map representing the relationship between the self-aligning ratio, the front-rear direction quantity of state, and the grip level, wherein said front-rear direction quantity of state is front-rear force or quotient obtained by dividing the front-rear force by the cornering power.