The Research And Realization Of The Collision Early—warning Assistant System For Train

ABSTRACT:With the acceleration of modernization and urbanization in our country, urban rail transit entered a period of rapid development because of urban transit characters. And its security has drawn public attention increasingly. Since trains might run without Automatic Train Protection (ATP) in reality, the operating safety was greatly reduced while traditional telephone block system is difficult to fully ensure the safe operation. Therefore, this thesis studied and designed the Collision Early-warning Assistant System for Train based on wireless ranging technology, applied on the trains without ATP.Firstly, the thesis introduces the technical requirements for the system and researchs several kinds of exisiting main wireless ranging technology. Considering it is more suitable for urban rail transit operating conditions, the wireless ranging technology based on chirp spread spectrum (CSS) signal and Symmetric Double Sided Two-Way Ranging method is elected to achieve the program after their feasibility has been analyzed and proved. On this basis, the thesis describes the structure and operating principle of the system.Secondly, the system design process is divided into two major parts, hardware and software, in the paper. The hardware design chapter detailedly explains each module circuit of the three main components of the system, the Ranging Terminal, the System Host and the Information Terminal. These module circuits include the power isolation conversion circuit, the signal conditioning circuit, the CPU circuit, the relay driver circuit and so on. The software design chapter expounds the realization of the system operating logic.Finally, functionality experiments of the system were conducted. The Ranging Terminal was tested through the dynamic and static experiments. On the other hand, several experiments were finished to test the functionality of the System Host and the Information Terminal. The results show that the Collision Early-warning Assistant System meets the design requirements, providing a benefit reference for the future safety program of urban rail transit.