Research On Automatic Location And Intelligent Bus Stop Announcement For Public Transport Vehicles

Intelligent transportation system (ITS) is the most important approach accepted worldwide to solve the problem of traffic congestions in cities with a very low cost-effectiveness ratio. Advanced public transport system is one of the most important parts in the urban transportation system, and many researches and attempts related to the intelligent public transport vehicles have come forth during recent years. However, many problems deal with bus location and stop announcement are urgent to be solved. Based on analysis of odometer positioning technology, combining the good characteristics of beacon positioning, using wireless sensor networks, an error correction algorithm of odometer reckoning with station beacons is presented. Aiming to improving the sound quality of bus stop reporter and making updating media data easy, an intelligent stop announcement design based on MP3/U disk is introduced. Based on CC1000 wireless sensor networks development platform, the odometer location error is corrected by measuring RSSI parameter and using maximum signal method. Research shows that the location error can be limited within 15m. Using advanced MCU AT89C51SND1C as the core of as OBU (On Board Unit), the MP3 format audio data is broadcasted with embedded MP3 hardwired decoder. Using STC12C54 series MCU as the CPU of RSU (Road Side Unit), the byte-alignment problem in receiving wireless RF data is analyzed, and a solution for it under SPI driving mode with manchester code is proposed. In order to improve the reliability of wireless communication, the characteristics of wireless links is studied, and a new measurement method based on MVI (Manchester Violation Indication) is suggested. Results show that the correction between MVI and PRR is up to -0.94. In conclusion, MVI is obviously superior to RSSI and better than LQI on the performance of measurement of link communication quality. It is suggested that MVI can be used as 4th measurement scale in measurement of wireless link quality. In addition, MCU operation system A51OS and CRC table lookup algorithm are also introduced.