Motion Sensing Techniques and Analysis for Direct Tire Pressure Monitoring

A direct tire pressure monitoring (TPM) system using pressure sensors mounted directly within the tires requires an overall battery life of up to 10 years. This is not easy to achieve with desirable lower cost lithium chemistry batteries with capacities less than 250 mA-hr. One method to extend battery life is to change the monitoring algorithm to a longer sample and/or transmission interval when the vehicle is not in motion. This paper will investigate various means to detect wheel motion, their impact on battery life and their relative cost to the TPM wheel sensor module.