Measurement of adherence between a vehicle wheel and the roadway

A method for the detection of an adherence characteristic between a tire with a deformable tread and a surface along which it is rolling, comprising the steps of:

• a) providing in the tread at least one first measuring element and at least one second element, each said tread element having a contact surface with the ground, the contact surface of the first measuring element being configured such that, during normal operation of a vehicle wheel equipped with the tire, the surfaces of the first and second elements come into contact with the ground on each revolution of the tire and, at least within a range of rolling conditions to be monitored, the contact surface of the first element slides relative to the ground during its passage through the contact area;
• b) generating a first signal that represents a tangential force in the contact surface of the first measuring element;
• c) detecting a variation of the first signal that characterizes a loss of adherence;
• d) producing an estimate of the friction potential in the contact surface of the first measuring element;
• and
• e) producing an estimate of adherence potential of the tire.

A method for detecting an adherence characteristic between a tire with a deformable tread and a surface over which it is rolling, comprising the steps of:

• a) providing in the tread at least one first measuring element and at least one second element, each said tread element having a contact surface with the ground, the contact surface of the first tread element being configured such that, during normal operation of a vehicle wheel equipped with the tire, the surfaces of the first and second elements come into contact with the ground on each revolution of the tire and, at least within a range of rolling conditions to be monitored, the contact surface of the first measuring element slides relative to the ground during its passage through the contact area;
• b) generating a first signal representing a tangential force in the zone of the contact surface of the first measuring element;
• c) detecting in the first signal the instant when the first measuring element enters the contact area;
• d) detecting in the first signal the instant when the first signal undergoes a variation that characterizes a loss of adherence;
• and
• e) producing an indication that characterizes an available adherence margin from a function of the first signal between the instant when entry into the contact area is detected and the instant when said characteristic variation is detected.