Unscented External Force and Torque Estimation for Quadrotors

TL;DR

This paper introduces an Unscented Quaternion Estimator-based algorithm for accurately estimating external forces and torques on quadrotors, improving robustness and performance in dynamic environments.

Contribution

The paper presents a novel nonlinear estimation algorithm using unit quaternions that outperforms existing methods in force and torque estimation for quadrotors.

Findings

Algorithm outperforms existing methods in simulation

Can generate force and torque profiles from experimental data

Enables quadrotors to stabilize in wind fields from moving fans

Abstract

In this paper, we describe an algorithm, based on the well-known Unscented Quaternion Estimator, to estimate external forces and torques acting on a quadrotor. This formulation uses a non-linear model for the quadrotor dynamics, naturally incorporates process and measurement noise, requires only a few parameters to be tuned manually, and uses singularity-free unit quaternions to represent attitude. We demonstrate in simulation that the proposed algorithm can outperform existing methods. We then highlight how our approach can be used to generate force and torque profiles from experimental data, and how this information can later be used for controller design. Finally, we show how the resulting controllers enable a quadrotor to stay in the wind field of a moving fan.