Acceleration-Based Control of Fixed-Wing UAVs for Guidance Applications

TL;DR

This paper develops an acceleration-level control framework for fixed-wing UAVs that translates guidance commands into autopilot-compatible body-rate and thrust commands, enabling advanced navigation strategies like proportional navigation.

Contribution

It introduces a novel outer-loop control method that maps acceleration commands to autopilot inputs, including an empirical thrust-energy relationship derived from flight data.

Findings

Accurate acceleration tracking demonstrated in real-flight tests.

Enables practical implementation of proportional navigation on fixed-wing UAVs.

Provides a mapping from desired accelerations to autopilot commands under flight constraints.

Abstract

Acceleration-commanded guidance laws (e.g., proportional navigation) are attractive for high-level decision making, but their direct deployment on fixed-wing UAVs is challenging because accelerations are not directly actuated and must be realized through attitude and thrust under flight-envelope constraints. This paper presents an acceleration-level outer-loop control framework that converts commanded tangential and normal accelerations into executable body-rate and normalized thrust commands compatible with mainstream autopilots (e.g., PX4/APM). For the normal channel, we derive an engineering mapping from the desired normal acceleration to roll- and pitch-rate commands that regulate the direction and magnitude of the lift vector under small-angle assumptions. For the tangential channel, we introduce an energy-based formulation inspired by total energy control and identify an empirical thrust-energy acceleration relationship directly from flight data, avoiding explicit propulsion modeling or thrust bench calibration. We further discuss priority handling between normal and tangential accelerations under saturation and non-level maneuvers. Extensive real-flight experiments on a VTOL fixed-wing platform demonstrate accurate acceleration tracking and enable practical implementation of proportional navigation using only body-rate and normalized thrust interfaces.