Tire Dynamic Rolling Radius Compensation Algorithm Based on Ax Sensor Offset Estimation for i-TPMS

Indirect Tire Pressure Monitoring System (i-TPMS) monitors inflation pressures in pneumatic tires using wheel speed sensor signals acquired from Anti-lock Braking System (ABS). In order to monitor the tire pressures indirectly, frequency analysis and wheel radius analysis are operating in parallel. This manuscript focuses on the wheel radius analysis. Changes in vehicle weight can influence the difference in rolling radius of the front and rear tires. In this manuscript, a tire rolling radius compensation algorithm using a longitudinal acceleration (Ax) sensor is proposed, without any additional cost. The Ax sensor offset caused by loaded mass is estimated when the vehicle is standstill as well as in motion. The tire rolling radius can be compensated using the estimated offset of the Ax sensor. The compensation amount of the tire rolling radius can be obtained based on the difference between the estimated value from the TPMS learning phase and the value from the TPMS detecting phase. Vehicle tests have been conducted in order to evaluate the proposed estimation algorithm. It has been shown from the test results that the proposed method provides satisfactory performance for compensating the tire rolling radius for the changes in vehicle weight.