Basic study on measurement of road friction coefficient with strain induced in a tire side face

Abstract

If road surface friction coefficient can be measured in real time, the performance of various vehicle control systems such as ABS (Antilock Braking System) and automatic braking systems can be improved. Therefore, many studies measuring road surface friction coefficient from strain in the bottom of a tire, which is inside of the tire tread and is the only part in contact with a road surface, has been done. However, a sensor installed on the bottom of a tire is easy to peel or damage because large deformation occurs locally on the bottom of a tire by rugged road surface. The authors studied a method of measuring road friction coefficient from strain induced in the tire sidewall. If the strain in the tire sidewall is used, stable measurement is expected because the tire sidewall is harder to deform locally than the bottom of a tire. First, we measured the relationship between vertical and horizontal loads acting on a ground contact surface of a tire and strain induced in the tire sidewall. Second, we established experimental formulas that can express these relations and methods of measuring road friction coefficient. Third, we confirmed that the proposal method can measure road friction coefficient at various ground planes with sufficient accuracy.

Keywords

• road friction coefficient
• side of tire
• measurement
• intelligent tire
• automobile