Full Vehicle Fusion

Node ID: fullVehicleFusion · Role: Filter · Realtime config: no

Description

Multi-sensor vehicle fusion combining IMU, GNSS, and wheel odometry. Outputs FusedVehiclePoseV2 with position, heading, velocity, and global coordinates.

Algorithm notes

How it works

This node chains the two other vehicle filters into one pipeline. The odometry stage (wheel speed + gyro, corrected by GNSS) produces a robust planar pose that keeps working through GNSS outages. The GNSS-IMU stage then treats that pose as its GNSS input (a “virtual GNSS” stream) and fuses it with the full IMU into the final smooth 3D pose, published on every IMU sample in local and WGS84 coordinates. The result is GNSS accuracy when reception is good and wheel-odometry dead reckoning when it is not.

The settings are the settings of the two stages, prefixed Odo: and GNSS:, plus a Pipeline group that controls the link between them.

What you must configure

The same installation geometry as the standalone filters:

• Odo: IMU-to-Car Rotation and Odo: IMU Turn Rate Axis - IMU mounting for the odometry stage.
• GNSS: IMU-to-Vehicle Rotation - IMU mounting for the GNSS-IMU stage.
• GNSS: GPS Antenna Offset - antenna position relative to the IMU (x forward, y left, z up).
• GNSS: Global Origin (optional) - fixes the local frame origin; otherwise the first fix is used.

Get these right before touching any tuning value - a wrong mounting rotation looks exactly like a badly tuned filter.

How it starts

The odometry stage initializes first: it needs an RTK Fixed position and a heading, from a dual-antenna receiver or from driving straight above Odo: Init Velocity Threshold. The GNSS-IMU stage then initializes from the virtual fixes. Expect no output until both stages are ready.

Tuning

The Pipeline defaults rarely need changing:

• Use Direct GNSS feeds real receiver fixes to the GNSS-IMU stage instead of the virtual stream. This gives up the outage coasting, so use it only with a reliable receiver.
• Keep Gate Height on RTK Fix and GNSS: Use Reported Accuracy on in the default virtual mode; they stop the second stage from over-trusting the synthesized fixes.
• Leave GNSS: Estimate GNSS-IMU Time Delay off in virtual mode - there is no real receiver to calibrate against.

Sensor trust is tuned per stage, exactly as in the standalone filters: the Odo: error values balance wheel/gyro dead reckoning against GNSS, the GNSS: error values balance the IMU against the virtual fixes.

Troubleshooting

• No output - the IMU stream stopped (output stops entirely), or the odometry stage never initialized (no RTK fix, or the vehicle never drove straight above the initialization speed).
• Output pauses after a jump in the odometry stage - the continuity check holds the second stage until Stable Samples Required clean samples arrive; usually a bad wheel-speed signal or repeated GNSS outages.
• Altitude jumps when the fix quality changes - keep Gate Height on RTK Fix on.
• Periodic freezes with marginal RTK - the filter cycles through RTK loss, settle and re-convergence; see GNSS: RTK Fix Lost Timeout (ms) and GNSS: RTK Settle After Restore (ms).
• To see which stage misbehaves, enable Output Intermediate Results and compare the odometry stage’s pose with the final output.

Inputs / Outputs

• Inputs: Imu, Gnss, VehicleSpeed
• Outputs: FusedPose, FusedVehiclePose, FusedVehiclePoseV2, GlobalFusedPose, FusionStateInt

Config aliases

FullVehicleFusionFilter, fullVehicleFusionFilter, fullVehicleFusion

Required feature

vehicular_fusion

Properties

Each row shows the setting’s label in the node’s Properties panel and, in code, its key in the node’s settings object in the config file. A setting omitted from the config file uses the default shown here.

Pipeline

Odometry - Core Tuning

Odometry - Outlier Handling

Odometry - Wheel Odometry & Turn Rate

Odometry - Orientation & Heading

Odometry - Stopped Detection

Odometry - Initialization & Convergence

Odometry - RTK & GNSS Quality

Odometry - IMU Mounting & Frames

GNSS - Core Tuning

GNSS - Outlier Handling

GNSS - Orientation & Heading

GNSS - Gravity & Velocity Updates

GNSS - Stopped Detection & ZUPT

GNSS - Initialization & Convergence

GNSS - RTK & GNSS Quality

GNSS - IMU Mounting & Frames

GNSS - Timing & Advanced Process Noise

GNSS - Output & Diagnostics

Example node definition

A minimal entry in config.json looks like the block below. Paste it under the sinks key, keyed by an instance name of your choice. All settings are optional: anything not listed under settings uses the default from the Properties table above. See The configuration file for how the sections and endpoint wiring work.

{
  "sinks": {
    "fullVehicleFusion": {
      "dataEndpoint": "inproc://fullVehicleFusion_data",
      "inputEndpoints": [
        "inproc://imu_data",
        "inproc://gnss_data",
        "inproc://vehicleSpeed_data"
      ],
      "inputDataFilter": [
        "Imu",
        "Gnss",
        "VehicleSpeed"
      ],
      "settings": {
        "odometryImuFusion": {
          "imuToCarRotation": {
            "w": 1,
            "x": 0,
            "y": 0,
            "z": 0
          },
          "imuTurnRateAxis": {
            "x": 0,
            "y": 0,
            "z": 1
          }
        },
        "gnssImuFusion": {
          "imuToCarRotation": {
            "w": 1,
            "x": 0,
            "y": 0,
            "z": 0
          },
          "gpsAntennaOffset": {
            "x": 0,
            "y": 0,
            "z": 0
          }
        }
      }
    }
  }
}