Gazebo and VBS4
behind one JSON-RPC.
Spawn multi-vehicle UAV and UGV fleets over Gazebo or VBS4 with one JSON-RPC interface. Ground-truth telemetry streams straight into the autopilot — deterministic tests, no EKF in the loop.
CrabSim
Dashboard preview coming soonGazebo and VBS4. Same control plane.
The autopilot stays backend-agnostic. CrabBridge protocol talks to either side — flip a flag, keep the test suite.
Gazebo
Open Robotics — HarmonicOpen-source, ODE / DART physics. CrabSim auto-launches gz sim with the world you choose, pipes telemetry from /gz-transport into the autopilot via SimBridge.
Lockstep clock, deterministic replay
Custom worlds via gazebo_terrain_generator
Camera + lidar + IMU sensor plugins
Headless in CI, GUI in development
VBS4
Bohemia Interactive SimulationsHigh-fidelity defence simulator. CrabBridge plugin exposes scenario, entity, environment and control surfaces over WebSocket JSON-RPC. CrabSim drives it the same way it drives Gazebo.
Bohemia-published terrain (multi-continent coverage)
Multi-vehicle scenarios shipped with VBS4
JSON or msgpack on the wire, per-connection
No SQF / ArmA scripting required
Spawn vehicles by JSON-RPC. Ground truth at 10 Hz. Auto-launches the backend.
Everything you need to put many vehicles in front of many tests without rebuilding the harness each release.
Multi-vehicle scenarios
Spawn copters, planes, AGVs and surface vessels in one world. Each gets its own MAVLink endpoint, system ID and ground-truth feed.
JSON-RPC control plane
WebSocket API for spawn, despawn, teleport, weather, time-of-day. Built-in dashboard at localhost:9000 mirrors the same calls.
Ground-truth telemetry
Bypass the EKF for deterministic tests. SimBridge streams perfect pose, velocity and orientation straight into the autopilot.
Backend-agnostic autopilot
crab-sitl --features crabsim never knows whether Gazebo or VBS4 is on the other end. CrabBridge protocol is the only contract.
Repeatable mission tests
Author scenarios as YAML or code. Replay against every PR with golden trajectories — catch regressions before they ship.
Fleet orchestration
Multiple vehicles, multiple GCS endpoints, single dashboard. C2 testing, swarm coordination, mission rehearsal.
How it works
CrabSim is the control plane. SimBridge is the protocol. The autopilot does not change.
Data flow
Gazebo or VBS4
pose, sensors, sceneSimBridge (UDP :9501)
CrabBridge protocol — ground truth + commandscrab-sitl --features crabsim
ground-truth replacement for EKFMAVLink → CrabStation / CrabCommander
fleet operator UISpawn a vehicle
Talk to ws://localhost:9000/ws with standard JSON-RPC 2.0. No client SDK required.
// Spawn a copter via JSON-RPC over WebSocket
{
"jsonrpc": "2.0",
"method": "spawn",
"params": {
"kind": "vehicle",
"vehicle_type": "copter",
"type": "ownship",
"system_id": 1,
"lat": 47.397742,
"lon": 8.545594,
"alt": 0.0,
"heading": 0.0
},
"id": 1
}Who runs CrabSim
Research
Validate new controllers, planners, and fusion stacks against repeatable scenarios. Swap from Gazebo to VBS4 without changing your test code.
Defence rehearsal
VBS4 terrain for mission rehearsal. Drive vehicles from any MAVLink-speaking C2 — no SQF required.
Continuous integration
Headless multi-vehicle SITL inside your pipeline. Catch regressions before they reach a real airframe.
Tell us your sim backend (Gazebo / VBS4 / in-house) — we'll quote bring-up.
CrabSim is commercial. Pricing depends on backend (Gazebo / VBS4 / in-house) and scenario count. Email info@crabpilot.dev for a quote.
Backend bring-up — Gazebo, VBS4, or your in-house simulator
Custom scenario authoring and automation hooks
CI integration: headless multi-vehicle tests in your pipeline
C2 + Commander integration for fleet exercises
Ongoing integration and feature work