The Design Of Tire Pressure Monitoring System Based On Wireless Transmission

Tire pressure monitor system (TPMS) is one of the important guarantee measures for the vehicles'safe steering. So it has extensive application foreground to research.Nowadays there are mainly two categories: indirect and direct TPMS. Direct system is prior to indirect system in terms of the aspects of measure accuracy and real time. In this thesis indirect TPMS is studied. Direct TPMS uses the pressure sensors to measure the pressure and transmits to the monitor which is installed in the driving platform by radio frequency modulation. The sensors are installed in the tires and powered by the Lisocl2 battery. The monitor shows the pressure and temperature momentarily, so the driver can master every tire's pressure condition easily. When the pressure is abnormal, the alarm works automatically.Guaranteeing the reliability in wireless communications and promoting the battery life in the transmitter are the technical difficulties for direct TPMS. Regarding these two points several aspects are studied:1. Analyze the parameters of the antenna's radiation resistance, wastage resistance, and inductance in direct TPMS. And then design the matching network according to them. Analyze the transmission circuits and the hub acting on the antenna's electromagnetism radiation direction and input impedance by using the simulation software.2. Research the low power consumption radio frequency circuits. Discuss how to make use of the switching characteristic of the audion and the interelectrode capacitance to achieve 2FSK modulation and the way to realize frequency multiplied and modulation by using the phase-locked loop. Consequently present the simulation results of the 2FSK modulation.3. Analyze the Heterodyne Doppler Frequency Shifts'effect on the receiving performance caused by the high velocity.4. Present the software and hardware designs of TPMS which include data acquisition, data processing, and the circuits of transmission, receiving and display. Optimize the software design to low the power of Remote Tire Pressure Monitoring, which based on low power hardware. And then do some experiments to validate the scheme's feasibility presented in this paper.