Estimation of Airship Aerodynamic Forces and Torques Using Extended Kalman Filter

Muhammad Wasim,Ahsan Ali

doi:10.1109/access.2020.2986190

Abstract

An airship is a lighter than air, aerial vehicle whose model is based on dynamic, aerodynamic, aerostatic and propulsion forces and torques. Apart from other, aerodynamic forces and toques are difficult to measure. In this work, an estimation scheme for aerodynamic forces and torques based on the Extended Kalman Filter (EKF) is presented. It is assumed that the airship attitude and position estimates are available. EKF estimates the airship body axes linear and angular velocities and aerodynamic forces and torques. As the method measures a complete aerodynamic model instead of measuring its individual parameters by utilizing minimum auxiliary state variables, it is computationally non-intensive and can provide online aerodynamic model information that can be used in controller implementation in a real-time environment. Nonlinear simulation environment is developed for the experimental airship and EKF performance is evaluated. For validating the estimator's performance, 3-σ uncertainty bounds and error analysis, estimator convergence analysis and it's closed-loop simulations with Sliding Mode Controller have been performed. The simulation results show that EKF successfully estimates the airship states and aerodynamic forces and torques with minimum estimation error enhancing the model-based nonlinear controller performance.

Highlights

Unmanned Aerial Vehicles (UAVs) are an area of interest in the modern age due to their numerous applications in monitoring, surveillance, transportation, exploration and photography tasks
This paper addresses the problem of estimating airship states and aerodynamic forces and torques using Extended Kalman Filter (EKF)
Airship body axes linear velocities, angular velocities, and aerodynamic forces and torques have been successfully estimated with small estimation error

Summary

Introduction

Unmanned Aerial Vehicles (UAVs) are an area of interest in the modern age due to their numerous applications in monitoring, surveillance, transportation, exploration and photography tasks In this context, an airship can provide a suitable UAV platform for these applications and many others due to some of its inherent and unique characteristics [1]. Airship has the ability to stay aloft with minimum power consumption and it has high payload capacity It can move with slow speed at low heights with long durations of flight and is intrinsically more stable than other platforms. The applications for which airship can be a potential candidate require different autonomous flight missions including path following, trajectory tracking, hovering, and attitude control, etc These missions can be performed by developing a reliable controller

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