Veloxity ROScopter Sim End-to-End¶

This guide runs the Veloxity Rust firmware inside the ROSflight standalone multirotor simulator, initializes that firmware through rosflight_io, then starts ROScopter autonomy and loads a waypoint mission.

Terminal Layout¶

Use separate terminals so long-running nodes stay visible.

Phase 1: Build The Shim¶

Terminal 1

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/Veloxity
source scripts/build_and_source_ros2_shim.zsh

This builds:

• target/debug/libsim.a: Rust sim firmware static library
• veloxity_sil_board_shim: ROS 2 C++ FFI bridge

Optional compile-only check:

cargo test -p sim
zsh scripts/build_and_source_ros2_shim.zsh

Phase 2: Start The Simulator And Rust Firmware¶

Terminal 1

export ROS_LOG_DIR=/tmp/veloxity-ros-log

ros2 launch veloxity_sil_board_shim multirotor_standalone_sil.launch.py \
  use_rviz:=true

The launch defaults to:

firmware:=veloxity

That means the simulator uses the Rust firmware endpoint:

/veloxity_sil_board

instead of upstream C firmware:

/sil_board

Both provide the sil_board/run service expected by rosflight_sil_manager.

Expected startup lines:

veloxity_sil_board ready: service=sil_board/run, pwm=sim/pwm_output
rosflight_io: Connecting over UDP to "localhost:14525", from "localhost:14520"
rosflight_io: Got HEARTBEAT, connected.
rosflight_io: Received all parameters

Compare Against C Firmware¶

Use this only when you specifically want the upstream ROSflight C firmware endpoint:

ros2 launch veloxity_sil_board_shim multirotor_standalone_sil.launch.py \
  firmware:=c \
  use_rviz:=true

Run the same firmware init, mission load, arm, and override sequence for both endpoints when checking parity. The Veloxity FFI shim is expected to present the same ROSflight SIL boundary as the C firmware: rosflight_sil_manager calls sil_board/run, sensor data enters through the standalone sim topics, MAVLink goes through unmodified rosflight_io, and motor output is published on sim/pwm_output.

One important detail is the IMU handoff. The shim latches the latest IMU sample after the first sim/sensors/imu/data message and includes that sample on every firmware step. This avoids false ROScopter IMU silence warnings caused by phase drift between the 400 Hz IMU publisher and the 400 Hz sil_board/run service timer. Lower-rate sensors remain availability-gated.

Brief Autopilot ERROR: Unhealthy estimator messages can occur around computer-control and mode transitions with both the Veloxity endpoint and upstream C endpoint. Treat those as ROSflight/C parity behavior unless they are paired with persistent ROScopter sensor silence warnings.

Phase 3: Initialize The Running Firmware¶

The firmware process is already running in Terminal 1. This phase sends setup commands to it through rosflight_io.

Terminal 2

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/Veloxity
source workspace/install/setup.zsh

Verify the simulator and Rust firmware endpoint are visible:

ros2 node list

You should see at least:

/rosflight_io
/veloxity_sil_board

Recommended: Veloxity Convenience Init¶

Run:

ros2 launch veloxity_sil_board_shim veloxity_multirotor_init_firmware.launch.py

This sends the following service calls in order:

1. /param_load_from_file
2. /calibrate_imu
3. /calibrate_baro
4. /param_write

Optional arguments:

ros2 launch veloxity_sil_board_shim veloxity_multirotor_init_firmware.launch.py \
  param_file:=/path/to/multirotor_combined.yaml \
  write_delay_s:=10

Manual Init Equivalent¶

Use this when debugging individual service calls.

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/rosflight/workspace/src/rosflight_ros_pkgs/rosflight_sim/params

ros2 service call /param_load_from_file rosflight_msgs/srv/ParamFile \
  "{filename: $(pwd)/multirotor_firmware/multirotor_combined.yaml}"

ros2 service call /calibrate_imu std_srvs/srv/Trigger
ros2 service call /calibrate_baro std_srvs/srv/Trigger
ros2 service call /param_write std_srvs/srv/Trigger

Watch Terminal 1 during init. You should see parameter traffic and the startup calibration errors recover.

Motor Output Isolation¶

Use MTR_OUT_MASK when checking motor order one output at a time. The mask is applied inside Veloxity after normal arming and idle-throttle handling, so disabled motor outputs stay at zero command even if ARM_SPIN_MOTORS is enabled.

Mask values are 0-based bitmasks:

-1: normal, all motor outputs pass through
 0: all motor outputs forced to zero
 1: only motor/output 0 enabled
 2: only motor/output 1 enabled
 4: only motor/output 2 enabled
 8: only motor/output 3 enabled

Set the mask through unmodified rosflight_io:

ros2 service call /param_set rosflight_msgs/srv/ParamSet \
  "{name: MTR_OUT_MASK, value: 1.0}"

Then arm the firmware and watch the physical motor or the sim output topic:

ros2 service call /toggle_arm std_srvs/srv/Trigger
ros2 topic echo /sim/pwm_output --once

In the simulator, a disabled motor channel should read 1000 us. The enabled motor channel should rise above 1000 us when the vehicle is armed and idle spin or throttle command is active. For hardware tests, remove props, start with MTR_OUT_MASK=0, then step through masks 1, 2, 4, and 8.

Return to normal operation when finished:

ros2 service call /param_set rosflight_msgs/srv/ParamSet \
  "{name: MTR_OUT_MASK, value: -1.0}"

Persistent Veloxity Params¶

Veloxity FFI sim parameters are saved through VELOXITY_SIM_PARAM_DIR.

The multirotor standalone launch defaults to:

/tmp/veloxity-sim-params/multirotor

Use a persistent path if you want params to survive cleanup of /tmp:

ros2 launch veloxity_sil_board_shim multirotor_standalone_sil.launch.py \
  veloxity_param_dir:=/some/persistent/path

Phase 4: Launch ROScopter Autonomy¶

Keep Terminal 1 running.

use_builtin_rc:=true

Terminal 3

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/Veloxity
source workspace/install/setup.zsh

ros2 launch roscopter_sim sim.launch.py

Expected ROScopter nodes include:

/autopilot
/estimator
/external_attitude_transcriber
/path_manager
/path_planner
/roscopter_truth
/trajectory_follower

Check with:

ros2 node list

Phase 5: Load A Mission¶

Terminal 4

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/Veloxity
source workspace/install/setup.zsh

Optional waypoint visualization:

ros2 run roscopter_gcs rviz_waypoint_publisher

Load the default ROScopter mission:

cd /home/skink/projects/ROSflight/.distrobox-home/ROSflight/rosflight/workspace/src/roscopter/roscopter/params

ros2 service call /path_planner/load_mission_from_file rosflight_msgs/srv/ParamFile \
  "{filename: $(pwd)/multirotor_mission.yaml}"

Verify waypoints:

ros2 topic echo /waypoints

Publish the next queued waypoint:

ros2 service call /path_planner/publish_next_waypoint std_srvs/srv/Trigger

Publish all initial waypoints:

ros2 param set /path_planner num_waypoints_to_publish_at_start 100

Manual waypoint example:

ros2 service call /path_planner/add_waypoint roscopter_msgs/srv/AddWaypoint \
  "{wp: {type: 1, w: [5.0, 5.0, -4.0], speed: 4.0, psi: 0.0, use_lla: false}, publish_now: true}"

Phase 6: Enable Autonomous Flight¶

If rc.py is running and you are not using VimFly or a transmitter:

ros2 service call /toggle_arm std_srvs/srv/Trigger
ros2 service call /toggle_override std_srvs/srv/Trigger

Phase 7: Monitor Flight¶

Useful topic echoes:

ros2 topic echo /estimated_state
ros2 topic echo /high_level_command
ros2 topic echo /command
ros2 topic echo /status

Useful rate checks:

ros2 topic hz /command
ros2 topic hz /sim/pwm_output
ros2 topic hz /imu/data
ros2 topic hz /sim/truth_state

If the vehicle drifts or you need to reset the standalone sim state:

ros2 service call /dynamics/set_sim_state rosflight_msgs/srv/SetSimState

Debug Checks¶

Use these before blaming ROScopter:

ros2 topic echo /sim/truth_state --once
ros2 topic echo /imu/data --once
ros2 topic echo /baro --once
ros2 topic echo /status --once
ros2 topic echo /rc_raw --once
ros2 topic echo /sim/pwm_output --once

References¶

• ROSflight manual sim tutorial: https://docs.rosflight.org/latest/user-guide/tutorials/manually-flying-rosflight-sim/
• ROSflight ROScopter sim tutorial: https://docs.rosflight.org/latest/user-guide/tutorials/setting-up-roscopter-in-sim/