Tire Pressure Monitoring System For Automobiles

With the development of the economy and society, automobile security has been attaching great importance. There are two kinds of automobile security. One is called the active security and the other is the passive security. Active security refers to the automobile's ability to avoid traffic accident while the passive security refers to the safeguard for the passenger or driver when accident happens. The technique of active security is used in wider applications due to its ability to avoid traffic accident. As one of the technique for active security, the technique of automobile tire pressure monitoring have taking important roles in the avoidance of traffic accident.A tire pressure monitoring system (TPMS) with high usability is developed in this thesis. There are direct and indirect TPMS due to their different ways of getting data. The direct method for data acquisition is adopted in this thesis because of the inferior inherent reliability of the indirect methods under certain circumstance. A high measurement precision is achieved.The developed TPMS in this thesis is composed of two core modules. One is the tire module and the other is central receiving station. Tire module is made up of by transducer unit, controlling unit and radiofrequency (RF) transmission unit. As the product of MEMS technique, the transducer unit integrates the sensors of pressure and temperature and digital interface. The enhanced 51 series microcontroller P87LPC767 and single integrated PLL transmitter are chosen for the controlling unit and radiofrequency transmission unit respectively. The detailed methods for data acquisition of pressure and temperature and the software flowchart are provided in this thesis. The dynamic half-partition approaching algorithm is used in data acquisition. The power consumption is reduced and the data acquisition is speeded up by use this algorithm. The hardware design, the coding and format of the transmitted signal are given based on the full and accurate analysis of the working mode and inner function of the integrated PLL transmitter. RF receiver, voice playing unit, liquid display unit, keyboard and debugging interface constitute the central receiving station. The software and hardware implementation of the RF receiver is described in detail. The essential for the hardware and software of the voice playing unit, liquid display unit, keyboard, and debugging interface is given respectively. The test result is given and analyzed. The results show that this TPMS achieves the performance of practicability for automobiles. The improvement of the system is discussed and the future development trend of the system is presented.