Sensing devices for intelligent tire that can measure friction coefficient of a road are researched so as to improve the performance of vehicle motion control systems such as ABS (anti-lock braking system). However, previous devices need complicated systems and do not have enough performance. This study proposes a simple tactile sensor that can measure the friction coefficient between a tire and road surface. The sensor is composed of a cantilever called “whisker” that is fixed to a base. The base is an elastic plate, and two strain gauges are attached to its surface. The whisker is passed through the hole opened to the tread of a tire and the sensor is attached to its inner surface. The whisker is covered by a domed rubber; the tip surface is used as the contact part. When the tire slips on a road and the contact part comes in contact with the surface, the vertical load and frictional force are applied to the contact part. Then, whisker is compressed and bended, so that the base is deformed elastically. The induced strains at the base from such deformation are measured by the abovementioned strain gauges. The study proposes the method determining the value of the vertical load and frictional force that acting on the tire from the measured strains and fabricates the prototype tactile sensor to confirm its availability.
