Automatic real-time speed limit warning based on radio frequency identification

An in–vehicle automatic speed limit warning system can help to prevent a significant number of speeding, which is one of the major causes of road accidents. However, current systems ae not providing satisfactory and consistent performance. This paper seeks to design speed limit reading system based on radio frequency identification (RFID) technologies for two different types of deployment, large scale permanent deployment and small scale temporary deployment. The aim of the designs is to provide a reliable and affordable solution for future driver warning systems or autonomous vehicle control systems to retrieve the speed limit information from roadside without involving any upper link services. For the system designs, we identified and tackled three primary issues, which are the tag location and deployment pattern for passive RFID adoption and the tag confusion in active RFID adoption. A prototype system was developed and validated in both laboratory test and an on–road field–trial.