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Co-authored-by: Hamish Willee <hamishwillee@gmail.com> Signed-off-by: Ramon Roche <mrpollo@gmail.com>
185 lines
8.5 KiB
Markdown
185 lines
8.5 KiB
Markdown
# Hardware in the Loop Simulation (HITL)
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:::warning
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HITL is [community supported and maintained](../simulation/community_supported_simulators.md).
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It may or may not work with current versions of PX4.
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See [Toolchain Installation](../dev_setup/dev_env.md) for information about the environments and tools supported by the core development team.
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:::
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Hardware-in-the-Loop (HITL or HIL) is a simulation mode in which normal PX4 firmware is run on real flight controller hardware.
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This approach has the benefit of testing most of the actual flight code on the real hardware.
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PX4 supports HITL for multicopters (using [jMAVSim](../sim_jmavsim/index.md) or [Gazebo Classic](../sim_gazebo_classic/index.md)) and VTOL (using Gazebo Classic).
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For a comparison of HITL and SIH on hardware, see [Hardware Simulation](../simulation/hardware.md).
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## HITL-Compatible Airframes {#compatible_airframe}
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The set of compatible airframes vs simulators is:
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| Airframe | `SYS_AUTOSTART` | Gazebo Classic | jMAVSim |
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| ---------------------------------------------------------------------------------------------------------------- | --------------- | -------------- | ------- |
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| [HIL Quadcopter X](../airframes/airframe_reference.md#copter_simulation_hil_quadcopter_x) | 1001 | Y | Y |
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| [HIL Standard VTOL QuadPlane](../airframes/airframe_reference.md#vtol_standard_vtol_hil_standard_vtol_quadplane) | 1002 | Y | |
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## HITL Simulation Environment {#simulation_environment}
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With Hardware-in-the-Loop (HITL) simulation the normal PX4 firmware is run on real hardware.
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JMAVSim or Gazebo Classic (running on a development computer) are connected to the flight controller hardware via USB/UART.
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The simulator acts as gateway to share MAVLink data between PX4 and _QGroundControl_.
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::: info
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The simulator can also be connected via UDP if the flight controller has networking support and uses a stable, low-latency connection (e.g. a wired Ethernet connection - WiFi is usually not sufficiently reliable).
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For example, this configuration has been tested with PX4 running on a Raspberry Pi connected via Ethernet to the computer (a startup configuration that includes the command for running jMAVSim can be found in [px4_hil.config](https://github.com/PX4/PX4-Autopilot/blob/main/posix-configs/rpi/px4_hil.config)).
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:::
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The diagram below shows the simulation environment:
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- A HITL configuration is selected (via _QGroundControl_) that doesn't start any real sensors.
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- _jMAVSim_ or _Gazebo Classic_ are connected to the flight controller via USB.
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- The simulator is connected to _QGroundControl_ via UDP and bridges its MAVLink messages to PX4.
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- _Gazebo Classic_ and _jMAVSim_ can also connect to an offboard API and bridge MAVLink messages to PX4.
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- (Optional) A serial connection can be used to connect Joystick/Gamepad hardware via _QGroundControl_.
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## HITL vs SITL
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SITL runs on a development computer in a simulated environment, and uses firmware specifically generated for that environment.
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Other than simulation drivers to provide fake environmental data from the simulator the system behaves normally.
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By contrast, HITL runs normal PX4 firmware in "HITL mode", on normal hardware.
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The simulation data enters the system at a different point than for SITL.
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Core modules like commander and sensors have HITL modes at startup that bypass some of the normal functionality.
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In summary, HITL runs PX4 on the actual hardware using standard firmware, but SITL actually executes more of the standard system code.
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## Setting up HITL
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## Check if HITL is in Firmware
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The module required for HITL ([`pwm_out_sim`](../modules/modules_driver.md#pwm-out-sim)) is not built into all PX4 firmware by default.
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To check if the module is present on your Flight Controller:
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1. Open QGroundControl
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2. Open **Analyze Tools > Mavlink Console**.
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3. Type the following command in the console:
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```sh
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pwm_out_sim status
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```
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4. If the returned value is `nsh: pwm_out_sim: command not found`, then you don't have the module installed.
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If `pwm_out_sim` is not present you will need to add it to the firmware in order to use HITL simulation.
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### Adding HITL modules to the Firmware
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Add the following key to the configuration file for your flight controller to include the required module (for an example see [boards/px4/fmu-v6x/default.px4board](https://github.com/PX4/PX4-Autopilot/blob/main/boards/px4/fmu-v6x/default.px4board)).
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Then re-build the firmware and flash it to the board.
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```text
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CONFIG_MODULES_SIMULATION_PWM_OUT_SIM=y
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```
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You can alternatively use the following command to launch a GUI configuration tool, and interactively enable them at the path: **modules > Simulation > pwm_out_sim**.
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For example, to update fmu-v6x you would use:
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```sh
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make px4_fmu-v6x boardconfig
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```
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### PX4 Configuration
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1. Connect the autopilot directly to _QGroundControl_ via USB.
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2. Select Airframe
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1. Open **Setup > Airframes**
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2. Select a [compatible airframe](#compatible_airframe) you want to test.
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Then click **Apply and Restart** on top-right of the _Airframe Setup_ page.
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3. Calibrate your [Manual Controller](../config/manual_control.md) (RC or Joystick), if needed.
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4. Setup UDP
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1. Under the _General_ tab of the settings menu, uncheck all _AutoConnect_ boxes except for **UDP**.
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5. (Optional) Configure your manual controller priority and failsafe:
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- [Enable a mode in `COM_RC_IN_MODE` that enables and prioritises the controllers you want to use](../config/manual_control.md#px4-configuration).
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The default `RC or MAVLink keep first` should work if you plan to only have a Joystick (no RC).
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- You can set [NAV_RCL_ACT](../advanced_config/parameter_reference.md#NAV_RCL_ACT) to disable manual control loss failsafe while flying in a simulation.
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:::tip
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The _QGroundControl User Guide_ also has instructions on [Joystick](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/setup_view/joystick.html) and [Virtual Joystick](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/settings_view/virtual_joystick.html) setup.
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:::
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Once configuration is complete, **close** _QGroundControl_ and disconnect the flight controller hardware from the computer.
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### Simulator-Specific Setup
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Follow the appropriate setup steps for the specific simulator in the following sections.
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#### Gazebo Classic
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::: info
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Make sure _QGroundControl_ is not running!
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:::
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1. Build PX4 with [Gazebo Classic](../sim_gazebo_classic/index.md) (in order to build the Gazebo Classic plugins).
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```sh
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cd <PX4-Autopilot clone>
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DONT_RUN=1 make px4_sitl_default gazebo-classic
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```
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2. Open the vehicle model's sdf file (e.g. **Tools/simulation/gazebo-classic/sitl_gazebo-classic/models/iris_hitl/iris_hitl.sdf**).
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3. Replace the `serialDevice` parameter (`/dev/ttyACM0`) if necessary.
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::: info
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The serial device depends on what port is used to connect the vehicle to the computer (this is usually `/dev/ttyACM0`).
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An easy way to check on Ubuntu is to plug in the autopilot, open up a terminal, and type `dmesg | grep "tty"`.
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The correct device will be the last one shown.
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:::
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4. Set up the environment variables:
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```sh
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source Tools/simulation/gazebo-classic/setup_gazebo.bash $(pwd) $(pwd)/build/px4_sitl_default
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```
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and run Gazebo Classic in HITL mode:
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```sh
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gazebo Tools/simulation/gazebo-classic/sitl_gazebo-classic/worlds/hitl_iris.world
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```
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5. Start _QGroundControl_.
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It should autoconnect to PX4 and Gazebo Classic.
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#### jMAVSim (Quadrotor only)
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::: info
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Make sure _QGroundControl_ is not running!
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:::
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1. Connect the flight controller to the computer and wait for it to boot.
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2. Run jMAVSim in HITL mode:
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```sh
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./Tools/simulation/jmavsim/jmavsim_run.sh -q -s -d /dev/ttyACM0 -b 921600 -r 250
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```
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::: info
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Replace the serial port name `/dev/ttyACM0` as appropriate.
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On macOS this port would be `/dev/tty.usbmodem1`.
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On Windows (including Cygwin) it would be the COM1 or another port - check the connection in the Windows Device Manager.
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:::
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3. Start _QGroundControl_.
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It should autoconnect to PX4 and jMAVSim.
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## Fly an Autonomous Mission in HITL
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You should be able to use _QGroundControl_ to [run missions](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/fly_view/fly_view.html#missions) and otherwise control the vehicle.
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