Simulation Quick Start

What the Sim Covers

• Physics — collisions, bouncing, gravity, ramps
• Game pieces — intake, hold, shoot, score
• Full robot control — drivetrain + all mechanisms
• Limelight AprilTag simulation — simulated vision pose estimates

Setup

git clone https://github.com/feds201/feds-central.git

Run the Sim

You can launch the simulator from the terminal or from VS Code.

Terminal:

cd robot/2026-rebuilt
./gradlew simulateJava

VS Code (menu):

1. Click the three-dot menu (···) in the top-right of the WPILib sidebar (or the WPILib icon in the top-right corner)
2. Select “Simulate Robot Code”
3. Choose “Sim GUI”

VS Code (command palette):

1. Ctrl+Shift+P → type “WPILib”
2. Select “Simulate Robot Code”
3. Choose “Sim GUI”

Either way, a WPILib simulation GUI window will open. Don’t close it — you’ll need it in a moment.

Set Up the Sim GUI

In the WPILib simulation GUI that opened:

1. Connect a controller:
   • Xbox / gamepad: Plug it in — it should appear automatically
   • No controller? Drag “Keyboard 0” onto “Joystick 0”
2. Click “Teleoperated” to enable the robot

Set Up AdvantageScope

1. Open AdvantageScope (installed with WPILib)
2. Connect via NetworkTables 4 (AdvantageKit)
3. Click the + button (top right) → select 3D Field
4. In the bottom-right Field section, select this year’s game
5. Add the robot:
   • In the left panel, expand RealOutputs → Sim → Drivetrain
   • Drag Pose3d into the Poses section (bottom center)
   • From the dropdown, select a robot model (use KitBot for now — instructions for adding our real robot model coming soon)
6. Add game pieces (2026 example — “Fuel” is the REBUILT ball):
   • In the left panel, find RealOutputs → Sim → GamePieces → Fuel
   • Drag it into the Poses section
   • From the dropdown, select Game Pieces → Fuel

You should now see the field, robot, and game pieces rendered in 3D.

Drive!

Useful Flags

Save Log Files (simLogging)

By default, the sim doesn’t write .wpilog files. To enable logging (useful for SysID characterization or offline analysis):

./gradlew simulateJava -PsimLogging=true

Logs are saved to the logs/ directory.

Simulation Speed

The sim runs in real-time by default. The speed multiplier is set in RebuiltSimManager.java:

SimulatedArena.overrideSimulationTimings(Seconds.of(DT), 1);
//                                                        ^ change this

Change the second argument to 2 for 2x speed, 5 for 5x, etc. (There’s no command-line flag for this yet — see future improvements below.)

Future Improvements

• More realistic AprilTag sim (currently reports perfect odometry with fake detections)
• Simulated ball detection for Limelight
• Command-line flag for time speedup
• More realistic intake (game pieces currently just disappear)
• Magnus effect on shot balls
• Better ramp physics (robot can’t “fly off” yet)
• Reduce ground physics jitter on settled balls
• Faster initialization