Method and device for estimating a friction coefficient between a tire and a road surface

A device for estimating a friction coefficient between a tire of a vehicle and a road surface, comprising:

• a state variable input section for obtaining state variable data representing conditions of the vehicle by using RPM sensors equipped on the vehicle;
• a friction coefficient estimator for estimating the friction coefficient by using the state variable data;
• a friction coefficient value storage keeping therein the estimated friction coefficient;
• a braking/steering monitoring section for monitoring a braking action and a steering action of the vehicle and generating signals when either of the braking action and the steering action are applied to the vehicle;
• and
• a control section receiving the signals from the braking/steering monitoring section and outputting the friction coefficient stored in the friction coefficient value storage when both or either of the braking action and the steering action are applied to the vehicle, and outputting the friction coefficient estimated by the friction coefficient estimator when the braking action and the steering action are not applied to the vehicle.

A method for estimating a friction coefficient between a tire of a vehicle and a road surface, comprising:

• generating at least one vehicle state variable data signal representative of the vehicle operational state;
• selectively filtering noise from said at least one data signal;
• mathematically modeling turbine torque based on said at least one data signal;
• estimating driving torque based on said modeled turbine torque and said at least one data signal;
• calculating a vehicle slip ratio based on said at least one data signal;
• and
• estimating the friction coefficient based on said slip ratio, driving torque and at least one data signal.

An apparatus for estimating and outputting a friction coefficient between a tire of a vehicle and a road surface for use in safety distance calculations in an adaptive vehicle, comprising at least one processor, the processor communicating with plural vehicle sensors to receive signals representative of the vehicle operational state, wherein said processor is programmed to:

• mathematically model turbine torque based said data signals;
• estimate driving torque based on said modeled turbine torque and selected data signals;
• calculate a vehicle slip ratio based on selected data signals;
• and
• estimate the friction coefficient based on said slip ratio, driving torque and data signals.

A method for estimating a friction coefficient between a vehicle tire and a road surface, comprising:

• generating at least one angular velocity data signal representative of an operational state of a vehicle;
• selectively filtering noise from said at least one angular velocity data signal;
• mathematically modeling turbine torque based on said at least one angular velocity data signal;
• estimating driving torque based on said turbine torque and said at least one angular velocity data signal;
• calculating a vehicle slip ratio based on said at least one angular velocity data signal;
• and
• estimating a friction coefficient based on said slip ratio, said driving torque, and said at least one angular velocity data signal.