# SIGMA-Free Introduction

## What is SIGMA-Free?

**SIGMA (Swarm Intelligence General Machine Learning Environment for Unmanned Aerial Vehicles)** is an open-source and free simulation platform jointly developed by the Swarm Intelligence Research Group at Beijing Institute of Technology and Beijing Daxiang Aviation Technology Co., Ltd. The system is specifically designed for flight simulation of low-altitude (≤500 m), low-speed (≤50 m/s), and small-size (wingspan ≤2 m, mass ≤20 kg) UAVs—collectively referred to as "low-slow-small" platforms—as well as commonly used small rotary-wing aircraft. SIGMA Free enables intuitive visualization of theoretical knowledge such as aerodynamics and flight control principles, and supports both single-UAV and swarm-level control and decision-making algorithms. It also provides full data interfaces for code debugging and development.

## What is SIGMA-Free designed for?

**SIGMA Free** is primarily designed for undergraduate and graduate students in science and engineering disciplines. It supports a wide range of applications, including routine learning in areas such as aircraft design, flight control, and programming in C++ or Python. The platform can also be used for algorithm reproduction, performance validation, and data processing in research projects. In addition, it provides high-fidelity image and video generation, supports continuous image capture, and can be used for pre-flight rehearsal of field experiments. SIGMA Free further enables advanced use cases such as real-map reconstruction, AI-based adversarial simulation, and deformable aircraft design.

## Why SIGMA-Free?

**SIGMA Free** includes two fixed-wing aircraft models and one rotary-wing aircraft model. The aerodynamic models have been optimized through experimental data identification, ensuring greater fidelity. All algorithms in the flight controllers are fully integrated into the simulation loop, allowing relevant parameters and control logic to be directly transferred to real-world flight tests.

<div><figure><img src="/files/P5IK7Ec5QPlJP5mwzTSy" alt=""><figcaption></figcaption></figure> <figure><img src="/files/3vRd2pqEMGERGyZko34M" alt=""><figcaption></figcaption></figure></div>

**SIGMA Free** adopts Unreal Engine 4 (UE4) as its rendering engine, enabling detailed and dynamic modeling of the physical characteristics and lighting properties of the aircraft, as well as the surrounding flight environment and target features. It also provides a dedicated rendering video channel that supports frame-by-frame image processing.

<figure><img src="/files/VGBVJr3qit4te9p6aUOZ" alt=""><figcaption></figcaption></figure>

**SIGMA Free** is a byproduct of a larger research project undertaken by our team. It supports the entire workflow—from aircraft design and controller development to real-world flight testing; from single-aircraft operations to swarm flight and swarm decision-making algorithm validation; from undergraduate projects to master's theses and doctoral research. We've experienced it all, and SIGMA Free is designed to help beginners get started quickly while offering advanced features that even experienced users will appreciate.

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## SIGMA-Free is permanently free!!

Download the Software:

{% embed url="<https://e.gitee.com/beijing-daxiang-airlines/repos/beijing-daxiang-airlines/SigmaInstaller>" %}

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Installation Guide and Related Documentation：

{% content-ref url="/pages/9U80CoIVFkYhXMCee060" %}
[Installation Guide](/tutorials-for-sigma-free/sigma-free-introduction/installation-guide.md)
{% endcontent-ref %}

Quick Start Guide：

{% content-ref url="/pages/NdLyIh9OhakJ8d1LKjQu" %}
[Quick Start](/tutorials-for-sigma-free/sigma-free-introduction/quick-start.md)
{% endcontent-ref %}


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