Software-In-The-Loop Simulation (SITL)

Introduction

Software-in-the-loop simulation creates a software simulation environment on a computer, simulating a real aircraft through a six-degree-of-freedom model; all sensors are virtual.

Note: software-in-the-loop simulation only supports UDP communication connections.

Simulation Environment Setup

• Operating system: Windows;
• Software: QEMU, ground control station.

Installing QEMU

1. Download QEMU for Windows – Installers (64 bit); version 7.1.0 or later is recommended;

2. Double-click the installer; the default installation on the C drive is fine;

3. After installation, add the QEMU installation directory C:\Program Files\qemu to the environment variables.

4. Open a Windows terminal and enter the following command to confirm the installation succeeded

   qemu-system-x86_64 --version

Installing the Ground Control Station

On the Downloads page, download and install the ground control station; installing it on the D drive is recommended.

Starting the Simulation

Creating a Connection

In the General section of the left sidebar of the ground station, click Device Connection; once on the device connection screen, click the Add button.

On the newly created device connection screen, click the product drop-down list and select Simulation, change the local port to 14550, and click OK.

Then click Connect to start the simulation and establish a communication link with the simulated UAV.

Main Screen

After starting the simulation, the UAV is shown on the map on the main screen.

The default airframe is a VTOL fixed-wing.

QEMU Terminal

In the Tools section of the left sidebar of the ground station, click Link Device; the link device screen shows the simulation terminal.

You can enter autopilot debug commands in the dialog box at the bottom, for example:

• View current processes

  ps

• View MAVLink communication status

  mavlink status info

Common Operations

Modifying Parameters

In the Tools section, click Autopilot Setup, then click All Parameters on the autopilot setup screen. Enter a keyword to find the corresponding parameter.

Saving Parameters

Click Save Parameters in the top-right corner.

Viewing Logs

In the SITL Scripts section, download the log extraction script extract_sd.bat, then place it in the SimulationBin folder under the ground station installation root directory, and copy sd_14550.bin and rename it to sd.bin.

Double-click the extract_sd.bat script to extract and create an sd folder in the current directory; flight logs can be found in that folder.

Before running extract_sd.bat, 7-Zip must be installed to the default path!