Wireless Train Control Project

The project involved the wireless automation of a model railway with independant CPU-controlled trains and signals. The project mainly consisted of a bespoke communication and control protocol, with the main concerns centering on Medium Access Control and constrained hardware environments.

The system was implemented using the Cyan Technology eCog1k development boards and RadioMetrix TDL2i wireless modems. A 4-layer network model and control system was written in the C programming language. A Linux PC was used as a monitoring and command station.

Downloads

Presentation: 10-minute overview of some aspects of the project. Download (PDF)

Presentation: Guaranteeing Network Message Delivery in Memory Limited Real Time Systems. Download (PDF)

Photos

The project involved modification of OO gauge (Hornby) trains. The electrical pickups on each train were isolated and train motors controlled using the development board, pulse-width-modulation and motor drivers. Each train carried its own power supply. In true prototype style, no effort was made to hide or shrink the electronics!

Since the focus of the project was on communication protocols and control, it would have been hugely undesirable to build a radio from scratch or implement low-level modulation algorithms. Instead, these plug-in RS232 radio modules were utilised from RadioMetrix. The TDL2i provides a transparent serial link. Multiple end-point support was added manually in the software protocols.

To implement signalling, a train detection system was built using the existing tracks. Adjacent track zones were electrically isolated and the train axles were soldered to ensure that trains shorted-out the rails in each zone. Thus the signals could detect the presence of a train. Each signal provided reports to adjacent sections to enable 3-phase signalling (yellow indication). The intention was to implant barcodes on the track so that trains could determine the distance and identify of the next signal.