Design of Dynamic Inversion and Explicit Model Following Flight Control Laws for Quadrotor UAS

2020 ◽  
Vol 65 (3) ◽  
pp. 1-16
Author(s):  
Umberto Saetti ◽  
Joseph F. Horn ◽  
Sagar Lakhmani ◽  
Constantino Lagoa ◽  
Tom F. Berger
Keyword(s):  
Flight Control ◽  
Flight Test ◽  
Parametric Model ◽  
Unmanned Aerial Systems ◽  
Model Parameters ◽  
Dynamic Inversion ◽  
Explicit Model ◽  
Control Laws ◽  
Model Following ◽  
Novel Approach

The objectives of this paper are to advance dynamic inversion (DI) and explicit model following (EMF) flight control laws for quadrotor unmanned aerial systems (UAS) and to develop an efficient strategy to compute the stability and performance robustness statistics of such control laws given parametric model uncertainty. For this purpose, a parametric model of a quadrotor is identified from flight-test data. The identified model is validated both in frequency and time domains. Next, DI and EMF flight control laws are designed for both inner attitude and outer velocity loops. Finally, a novel approach based on an unscented transform is used to evaluate the statistics of the controller's performance based on the statistics of the uncertain model parameters.

Flight Control Law Using Nonlinear Dynamic Inversion Combined With Quantitative Feedback Theory

1998 ◽  
Vol 120 (2) ◽  
pp. 208-215 ◽  
Author(s):  
S. A. Snell ◽  
P. W. Stout
Keyword(s):  
Flight Control ◽  
High Performance ◽  
Large Angle ◽  
Dynamic Inversion ◽  
Control Law ◽  
Pitching Moment ◽  
Quantitative Feedback Theory ◽  
Control Laws ◽  
Nonlinear Version ◽  
Plant Uncertainty

A method of designing control laws for uncertain nonlinear systems is presented. Dynamic inversion is used to partially linearize the dynamics and then a nonlinear version of quantitative feedback theory (QFT) is applied to the resulting system which assures robustness to plant uncertainty. The design yields good performance with low bandwidth. An application to the design of flight control laws for a high performance aircraft is presented. The control laws demonstrate good performance by accurately following large angle of attack commands at flight speeds ranging from 53 to 150 m/s. Robustness is verified by including ±20 percent variations in pitching moment derivatives. The reduced bandwidth compared to a fixed-gain, linear design, leads to greatly reduced actuator transients, which should give improved reliability and longer life for the actuators and associated structure.

Stalling transport aircraft

2013 ◽  
Vol 117 (1198) ◽  
pp. 1183-1206 ◽  
Author(s):  
P. J. Bolds-Moorehead ◽  
V. G. Chaney ◽  
T. Lutz ◽  
S. Vaux
Keyword(s):  
Wind Tunnel ◽  
Flight Control ◽  
Flight Test ◽  
High Angle ◽  
Flight Testing ◽  
Control Laws ◽  
Transport Aircraft ◽  
Wind Tunnel Data ◽  
Predictive Validation ◽  
Flight Deck

Abstract Airbus and Boeing are cooperatively presenting this topic dealing with transport aircraft stalls. The paper will begin by defining a stall, followed by a review of requirements, predictive validation and flight testing. There are various ways of designing modern jet transports for the stall regime such as aerodynamic approaches, flight deck indications, and augmentation control laws to deal with the high angle-of-attack (α) arena. The goal of augmented control laws for high α is common – no full aerodynamic stall or loss of climb performance should occur in the operational flight envelope, in Normal flight control modes. The validation techniques employed in preparation for a flight test campaign will follow. These include flight characteristic predictions based on wind-tunnel data as well as pilot-in-the-loop simulation rehearsals. The preparation for flight testing will be reviewed from both the engineer and pilot viewpoints. This will be followed by a review of various flight testing that has been conducted. The paper will close with a brief foray into what the future of transport stalls could be – perhaps protection features in degraded flight control modes? What are the benefits as well as drawbacks to increased augmentation for high α?

Incremental Nonlinear Dynamic Inversion for the Apache AH-64 Helicopter Control

2020 ◽  
Vol 65 (2) ◽  
pp. 1-16
Author(s):  
Marilena D. Pavel ◽  
Perumal Shanthakumaran ◽  
Qiping Chu ◽  
Olaf Stroosma ◽  
Mike Wolfe ◽  
...  
Keyword(s):  
Flight Control ◽  
Nonlinear Dynamic ◽  
Visual Environment ◽  
Model Parameters ◽  
Dynamic Inversion ◽  
Partial Control ◽  
Handling Qualities ◽  
Control Effectiveness ◽  
Effectiveness Model ◽  
Nonlinear Dynamic Inversion

Incremental nonlinear dynamic inversion (INDI)-based controller is a promising technique that can be adopted to control dynamic systems with high nonlinearities and extended cross-coupling effects. This paper presents the incremental strategy adopted as a sensor-based controller approach for the Apache AH-64D Longbow helicopter. The strength of the INDI sensor– based approach is that it does not require a detailed vehicle model as it uses only a control effectiveness model and estimates of the vehicle angular accelerations replacing the rest of the model. The weakness is its sensitivity to measurement and actuator delays, demanding additional estimations of model parameters and control effectiveness tuning. Using the Boeing FLYRT Apache model to simulate the vehicle dynamics, the paper has developed three adaptation schemes connecting the INDI sensor–based approach to the Apache partial control authority set as ±20% authority in all axes. The goal was to redesign the existing Apache's flight control systems and demonstrate handling qualities improvements for hover and low-speed flight in normal and degraded visual environment. Implementing the attitude command attitude hold and translational rate command response types in the system through the INDI controller, the paper demonstrates that improvements from Level 2 to Level 1 handling qualities can be achieved when flying the Aeronautical Design Standard-33 (ADS-33E-PRF) hover and pirouette maneuvers in a degraded visual environment.

scholarly journals Historical Overview of Research in Reconfigurable Flight Control

2005 ◽  
Vol 219 (4) ◽  
pp. 263-275 ◽  
Author(s):  
M Steinberg
Keyword(s):  
Intelligent Control ◽  
Flight Control ◽  
Flight Test ◽  
Historical Overview ◽  
Reconfigurable Control ◽  
Control Laws ◽  
Loop Control ◽  
Software Algorithms ◽  
Lifting Surfaces ◽  
Initial Research

This article presents a historical overview of research in reconfigurable flight control. For the purpose of this article, the term ‘reconfigurable flight control’ is used to refer to software algorithms designed specifically to compensate for failures or damage of flight control effectors or lifting surfaces, using the remaining effectors to generate compensating forces and moments. This article will discuss initial research and flight testing of approaches based on explicit fault detection, isolation, and estimation, as well as later approaches based on continuously adaptive and intelligent control algorithms. In addition, approaches for trajectory reshaping of an impaired aircraft with reconfigurable inner loop control laws will be briefly discussed. Finally, there will be some discussion on current implementations of reconfigurable control to improve safety on production and flight test aircraft and remaining challenges to enable broader use of the technology, such as the difficulties of flight certification of these types of approaches.

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