US Patent 7845218 Tire state estimator and tire state estimation method

A tire state estimator includes a lateral force upper limit estimating section, a lateral force estimating section, and a tire slip angle estimating section. The lateral force upper limit estimating section calculates an estimated tire lateral force upper limit, on a basis of an estimated tire slip angle and a measured tire self aligning torque. The lateral force estimating section calculates an estimated tire lateral force, on a basis of the estimated tire lateral force upper limit calculated by the lateral force upper limit estimating section and the estimated tire slip angle. The tire slip angle estimating section calculates the estimated tire slip angle, on a basis of the estimated tire lateral force calculated by the lateral force estimating section and a measured vehicle state.