A flatness-based saturated controller design for a quadcopter with experimental validation

TL;DR

This paper introduces a flatness-based control method with input saturation handling for quadcopters, validated through simulations and real-world experiments, ensuring stability, constraint satisfaction, and low computational complexity.

Contribution

It presents a novel flatness-based control scheme explicitly managing input constraints with saturation, validated experimentally on a nano-drone platform.

Findings

Ensures quadcopter stability with input saturation constraints.

Validated control scheme through simulations and real-world experiments.

Achieves low computational complexity suitable for embedded systems.

Abstract

Using the properties of differential flatness, a controllable system, such as a quadcoper model, may be transformed into a linear equivalent system via a coordinate change and an input mapping. This is a straightforward advantage for the quadcopter's controller design and its real-time implementation. However, one significant hindrance is that, while the dynamics become linear in the new coordinates (the flat output space), the input constraints become convoluted. This paper addresses an explicit pre-stabilization based control scheme which handles the input constraints for the quadcopter in the flat output space with a saturation component. The system's stability is shown to hold by Lyapunov-stability arguments. Moreover, the practical viability of the proposed method is validated both in simulation and experiments over a nano-drone platform. Hence, the flatness-based saturated controller not only ensures stability and constraints satisfaction, but also requires very low computational effort, allowing for embedded implementations.