A High-Gain Observer Approach to Robust Trajectory Estimation and Tracking for a Multi-rotor UAV

TL;DR

This paper presents a robust high-gain observer-based control strategy for multi-rotor UAVs that effectively estimates unmeasured states and disturbances, enabling accurate trajectory tracking and landing on moving targets despite uncertainties.

Contribution

It introduces an extended high-gain observer framework combined with a robust output feedback controller for improved UAV trajectory estimation and tracking under disturbances and model uncertainties.

Findings

Successful numerical simulations demonstrating accurate trajectory tracking.

Experimental validation showing effective landing on moving ground vehicles.

Theoretical stability analysis confirming robustness of the control approach.

Abstract

Using the context of trajectory estimation and tracking for multi-rotor unmanned aerial vehicles (UAVs), we explore the challenges in applying high-gain observers to highly dynamic systems. The multi-rotor will operate in the presence of external disturbances and modeling errors. At the same time, the reference trajectory is unknown and generated from a reference system with unknown or partially known dynamics. We assume the only measurements that are available are the position and orientation of the multi-rotor and the position of the reference system. We adopt an extended high-gain observer (EHGO) estimation framework to estimate the unmeasured multi-rotor states, modeling errors, external disturbances, and the reference trajectory. We design a robust output feedback controller for trajectory tracking that comprises a feedback linearizing controller and the EHGO. The proposed control method is rigorously analyzed to establish its stability properties. Finally, we illustrate our theoretical results through numerical simulation and experimental validation in which a multi-rotor tracks a moving ground vehicle with an unknown trajectory and dynamics and successfully lands on the vehicle while in motion.