Smartphone-Based Vehicular Tire Pressure and Condition Monitoring

Proper tire maintenance is key to the safe and efficient operation of vehicles. Without frequent inspection, pressure can drop and tread can wear down, increasing drag and reducing traction. While modern cars make use of Tire Pressure Monitoring Systems (TPMS), these systems may only identify differential changes in pressure and older vehicles lack sensing entirely. To address this problem, we applied mobile phone accelerometer and GPS data to calculate predicted and true wheel rotational frequencies, and therefore infer tire circumference and related pressure or tread depth. Through tree-based classification, we were able to identify from among five tire states with 20% increases or decreases in tire pressure with 80% accuracy using only a mobile phone. The models demonstrated are robust to road surface and the main differentiating element, the GPS/accelerometer velocity ratio, has proven generalizable across vehicle makes, models, and tire sizes.