Digital Rail

Digital Rail is an interlocking system for model railways. It aims to be as realistic as possible and is based on the German railway system. It is written in Java and is designed to be used on a Raspberry Pi (Zero).

Basis of the interlocking is a graph using an adjacency list. By using the depth first search algorithm, the interlocking is able to determine all possible paths in the graph. Not every path makes logically sense for a train, so we need to filter them out. Keep in mind that if there are several paths between two nodes, the interlocking will only use the first one it finds. This will be solved in the future.

It uses a declarative API to define just anything. The following example shows how a signal could look like:

apiVersion: rail.yannick.sh/v1alpha1
kind: Signal

metadata:
    name: signal-A

    labels:
        rail.yannick.sh/displayName: A
        rail.yannick.sh/raspberry: rpi
        rail.yannick.sh/raspberry-stop-pin: 19
        rail.yannick.sh/raspberry-clear-pin: 26

spec:
    indication: stop

You can find all example resources in ./examples.

State of Development

• 🚧 Interlocking
  • ✅ Find all paths (Spurplan)
  • ✅ Determine indication/position of signals/switches on a path
  • ✅ Lock all elements on a path and transmit the indication/position of signals/switches to the concentrator
  • ✅ Release single elements on a path
  • ⛔ Find the best path (currently: first path)
  • ⛔️ Provide flank protection (Flankenschutz)
  • ✅ Allocate elements in specific order (switches -> flank protective signals -> signals -> starting signal)
  • ⛔️ Communication between interlocking systems
• 🚧 Track Field Concentrator (Gleisfeldkonzentrator, GFK)
• 🚧 CLI
• ⛔️ UI
• ⛔️ Decoders
• ⛔️ Track vacancy detection system (Gleisfreimeldeanlage)
• ⛔ Documentation (I'm so sorry ...)

Current look and feel

Right now, I have implemented a simple track graph on a breadboard using LEDs both for signals and switches. As I want to cover motors for the switches at a later point, I have used a relay to simulate the motor. If the switch should point to its alternate position, the blue LED is on. If the switch should point to its base position, the red LED is off. The image below shows my setup:

The above state can be achieved by typing A.P2 into the CLI. The track graph looks like this:

flowchart LR
    toLeft --- A
    A --- SW1
    SW1 --- N2
    N2 --- P2
    P2 --- SW2
    SW1 --- N1
    N1 --- P1
    P1 --- SW2
    SW2 --- F
    F --- toRight

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Usage

Build

mvn clean package

Run

# On the Pi
scp -r distribution user@pi:/home/user
sudo ./distribution/run.sh # in /home/user

# On your machine
java -jar digital-rail-interlocking/target/digital-rail-interlocking-1.0.0-SNAPSHOT.jar
java -jar digital-rail-cli/target/digital-rail-cli-1.0.0-SNAPSHOT-jar-with-dependencies.jar

Architecture

Real World Architecture

The goal is to create a topology inspired by Digitale Schiene Deutschland (digital rail Germany). This would result in the following architecture:

flowchart TD
    UI -- Ethernet --- Interlocking
    Interlocking -- Ethernet --- Concentrator1[Field Track Concentrator]
    Concentrator1 --- Element1[Track Element]
    Element1 --- Element2[Track Element]
    Element2 --- Element3[Track Element]
    Element3 -- Ethernet --- Concentrator1
    Interlocking -- Ethernet --- Concentrator2[Field Track Concentrator]
    Interlocking -- Ethernet --- Concentrator3[...]

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Current Architecture

The current architecture is a bit different, as the project is under development. The following diagram shows the current architecture:

flowchart TD
    CLI -- Ethernet --- Interlocking
    Interlocking -- Socket --- Concentrator[Field Track Concentrator RPI]
    Concentrator -- GPIO --- Element1[Track Element]
    Concentrator -- GPIO --- Element2[Track Element]
    Concentrator -- GPIO --- Element3[Track Element]

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