Abstract: An apparatus and method for determining operational parameters of a tire in terrestrial vehicles are described. Velocity of a vehicle is determined, for example, by using the global positioning system. A free-rolling radius of a free-rolling wheel is determined from the velocity and angular velocity of the free-rolling wheel, which is determined with a wheel sensing unit when angular acceleration is negligible. Absolute velocity and acceleration are determined from the free-rolling radius and the angular velocity. Longitudinal stiffness and effective radius of the tire on a monitored wheel are determined. For a free-rolling wheel, these parameters may be determined separately. For a driven wheel, these parameters are determined simultaneously when the vehicle is accelerating using a nonlinear estimation algorithm.

Abstract: A method for determining a sideslip angle of a terrestrial vehicle that moves on wheels by using a global positioning system (GPS) receiver. The GPS receiver is mounted in the vehicle and measures the horizontal velocity of the vehicle as well as its attitude. The sideslip angle of the vehicle at the GPS receiver is obtained from these measurements. The body sideslip angle and tire sideslip angles are derived by translating the sideslip angle at the GPS receiver to the center of gravity and to the wheels. Alternatively, an on-board gyroscope is provided for measuring vehicle attitude while the horizontal velocity is obtained from the GPS receiver. The method is extended to derive wheel slip and tire cornering stiffness. The vehicle states derived by the method can be used in a stability control system for stabilizing the motion of the vehicle.

Abstract: A method for determining a sideslip angle of a terrestrial vehicle that moves on wheels by using a global positioning system (GPS) receiver. The GPS receiver is mounted in the vehicle and measures the horizontal velocity of the vehicle as well as its attitude. The sideslip angle of the vehicle at the GPS receiver is obtained from these measurements. The body sideslip angle and tire sideslip angles are derived by translating the sideslip angle at the GPS receiver to the center of gravity and to the wheels. Alternatively, an on-board gyroscope is provided for measuring vehicle attitude while the horizontal velocity is obtained from the GPS receiver. The method is extended to derive wheel slip and tire cornering stiffness. The vehicle states derived by the method can be used in a stability control system for stabilizing the motion of the vehicle.