New Project: Model Trains

Ok, this isn't actually a new project as I've been working on it for months now. The aim is to create a model railway that operates in a decentralised automonous way. Here is the basics of how I want it to work:

• Each train will be controlled by an on-board Mote. These are basically small circuits with a microcontroller and radio chip. Trains can communicate with each other wirelessly and form a peer-to-peer mesh network. I am using the (now discontinued) Moteiv tMote Sky model of Mote, as I have five available to me. They have a TI MSP430 MCU and CC2420 2.4GHz radio chip.
• Fixed track features such as points, signals and level crossings will each have a small PIC-based controller. These will all be connected together using a wired RS-485 bus. A single Mote will also be connected to this bus and will act as a wireless interface to all of the fixed features.
• Trains will have knowledge of the track layout, which will be divided up into blocks. The boundary between blocks will have some form of marker embedded under the track so that trains know when they have entered a block. Trains will use dead-reckoning within blocks to estimate their position.
• Each train will allow its schedule to be programmed into it. This will consist of a list of waypoints (stations) that it should visit. Trains will use their knowledge of the track layout to plan a route and follow their schedule.
• Trains will communicate wirelessly to ensure that no block of track is occupied by more than one train at once. This will be done with a token passing protocol, where trains may hold the token for a number of track segments and pass them to other trains as required.
• The fixed track features (e.g. points) will be controlled by the trains themselves by sending messages on the radio to the Mote that is acting as an interface to the fixed features. For example, if a train holds the control token for a block of track with a set of points in, it will be able to set the points as required by its route.

The key aims of the project are that, aside from programming schedules, trains operate autonomously and without any central controlling computer.

Now for a really boring video that showed my progress some months ago. It shows a Mote controling a train and simply moving it backwards and forwards by a fixed amount. Nothing very special at this stage...