scholarly journals Applying Eigenstructure Assignment to Inner-Loop Flight Control Laws for a Multibody Aircraft

2021 ◽  
Author(s):  
Alexander Köthe ◽  
Robert Luckner
Keyword(s):  
Rigid Body ◽  
Flight Control ◽  
Reference Model ◽  
Equations Of Motion ◽  
Unmanned Aircraft ◽  
Control Law ◽  
Eigenstructure Assignment ◽  
Control Laws ◽  
Target Model ◽  
Alternative Technologies

AbstractUnmanned aircraft used as high-altitude platform system has been studied in research and industry as alternative technologies to satellites. Regarding actual operation and flight performance of such systems, multibody aircraft seems to be a promising aircraft configuration. In terms of flight dynamics, this aircraft strongly differs from classical rigid-body and flexible aircraft, because a strong interference between flight mechanic and formation modes occurs. For unmanned operation in the stratosphere, flight control laws are required. While control theory generally provides a number of approaches, the specific flight physics characteristics can be only partially considered. This paper addresses a flight control law approach based on a physically exact target model of the multibody aircraft dynamics rather than conventionally considering the system dynamics only. In the target model, hypothetical spring and damping elements at the joints are included into the equations of motion to transfer the configuration of a highly flexible multibody aircraft into one similar to a classical rigid-body aircraft. The differences between both types of aircraft are reflected in the eigenvalues and eigenvectors. Using the eigenstructure assignment, the desired damping and stiffness are established by the inner-loop flight control law. In contrast to other methods, this procedure allows a straightforward control law design for a multibody aircraft based on a physical reference model.

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.

Continuum of Motion Equations and Control Laws for the Inverted Pendulum Cart and Rotary Pendulum

2020 ◽  
Author(s):  
Constance Lare ◽  
Warren N. White
Keyword(s):  
Inverted Pendulum ◽  
Equations Of Motion ◽  
Control Law ◽  
Control Laws ◽  
Motion Equations ◽  
Base Radius ◽  
Limiting Condition ◽  
And Control ◽  
The Given ◽  
Insight Into

Abstract This paper questions whether the controller properties for a given rigid body mechanical system still apply as the given system is changed. As a first attempt in this investigation, the controller for the underactuated rotary pendulum is investigated as the system morphs into an underactuated inverted pendulum cart. As the limiting condition of the inverted pendulum cart is approached, the investigation allows the controller to also morph. The authors show that, as the pendulum base radius grows, the rotary pendulum equations of motion morph into the inverted pendulum cart dynamics. The paper presents necessary conditions for the successful morphing of the dynamic equations. The morphing process for the controller tests the idea whether the control law also satisfies the same continuum basis as the motion equations. The paper presents a framework for the class of controllers investigated for providing insight into when the controller morphing may be successful. This paper presents dimensionless quantities that render the equations of motion and controller for the inverted pendulum cart and rotary pendulum into dimensionless form. These dimensionless quantities allow comparison of controllers and systems that are not possible through simple inspection. This comparison ability is especially useful for quantifying the nonlinearities of a given system and controller compared to another system and controller having different parameter sizes, a comparison rarely seen in the control literature.

A continuation design framework for nonlinear flight control problems

2006 ◽  
Vol 110 (1104) ◽  
pp. 85-96 ◽  
Author(s):  
T. S. Richardson ◽  
M. H. Lowenberg
Keyword(s):  
Flight Control ◽  
Systematic Approach ◽  
Control Law ◽  
Control Problems ◽  
Eigenstructure Assignment ◽  
Design Framework ◽  
Aircraft Control ◽  
Fighter Aircraft ◽  
Highly Nonlinear ◽  
Fifth Order

Abstract A methodology referred to as the continuation design framework is developed for application to nonlinear flight control problems. This forms the basis of a systematic approach to control system design for aircraft operating in highly nonlinear regions of the flight envelope. The essence of the continuation design framework is to combine bifurcation analysis with modern control methods such as eigenstructure assignment. Theoretical and practical issues of the approach are discussed with particular reference to the problems posed by agile fighter aircraft. The proposed methodology is applied to a fifth order hypothetical aircraft model and is shown to provide a visible, flexible and logical approach to nonlinear aircraft control law design.

scholarly journals Three-axis coupled flight control law design for flying wing aircraft using eigenstructure assignment method

2020 ◽  
Vol 33 (10) ◽  
pp. 2510-2526
Author(s):  
Lixin WANG ◽  
Ning ZHANG ◽  
Ting YUE ◽  
Hailiang LIU ◽  
Jianghui ZHU ◽  
...  
Keyword(s):  
Flight Control ◽  
Control Law ◽  
Eigenstructure Assignment ◽  
Assignment Method

Case Studies of System Identification Modeling for Flight Control Design

2013 ◽  
Vol 58 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Christina M. Ivler ◽  
Mark B. Tischler
Keyword(s):  
System Identification ◽  
Flight Control ◽  
Control Design ◽  
Flight Test ◽  
Unmanned Aircraft ◽  
Integrated System ◽  
Control Law ◽  
Dynamics Model ◽  
Identification Methods ◽  
Flight Dynamics Model

Flight control design and analysis requires an accurate flight dynamics model of the bare airframe and its associated uncertainties, as well as the integrated system model (block diagrams), across the frequency range of interest. Frequency response system identification methods have proven to efficiently fulfill these modeling requirements in recent rotorcraft flight control applications. This paper presents integrated system identification methods for control law design with flight-test examples of the Fire Scout MQ-8B, S-76, and ARH-70A. The paper also looks toward how system identification could be used in new modeling challenges such as large tilt-rotors and uniquely configured unmanned aircraft.

Autonomous Mission Management Based Nonlinear Flight Control Design for a Class of Hybrid Unmanned Aerial Vehicles

2021 ◽  
Vol 01 (02) ◽  
pp. 2150009
Author(s):  
Kemao Peng
Keyword(s):  
Flight Control ◽  
Closed Loop ◽  
Main Idea ◽  
Loop System ◽  
Control Law ◽  
Closed Loop System ◽  
Control Laws ◽  
Mission Management ◽  
Rotary Wing ◽  
Transition Flight

In this paper, a nonlinear flight control law is designed for a hybrid unmanned aerial vehicle (UAV) to achieve the advanced flight performances with the autonomous mission management (AMM). The hybrid UAV is capable of hovering like quadrotors and maneuvering as fixed-wing aircraft. The main idea is to design the flight control laws in modules. Those modules are organized online by the autonomous mission management. Such online organization will improve the UAV autonomy. One of the challenges is to execute the transition flight between the rotary-wing and fixed-wing modes. The resulting closed-loop system with the designed flight control law is verified in simulation and the simulation results demonstrate that the resulting closed-loop system can successfully complete the designated flight missions including the transition flight between the rotary-wing and fixed-wing modes.

Model-Based Sliding Mode Control for a Robot With SMA Actuators

2005 ◽  
Author(s):  
Hashem Ashrafiuon ◽  
Jala Vijay Reddy
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Equations Of Motion ◽  
Constitutive Law ◽  
Control Law ◽  
Robot Arm ◽  
Control Laws ◽  
Sma Actuators ◽  
Model Based ◽  
Mode Control

This paper presents a model-based sliding mode control law for a planar three-degree-of-freedom robot arm actuated by two rotary Shape Memory Alloy (SMA) actuators and a servomotor. The SMA actuators use a combination of SMA wires and pulleys to produce rotational motion. A model of the robot is developed which combines robot equations of motion with the SMA wire heat convection, constitutive law, and phase transformation equations. Two second-order sliding surfaces are defined leading to derivation of asymptotically stable control laws within the actuation region of the SMA wires. Outside the actuation region, constant inputs are used based on the one-way nature of the SMA actuators. The control law is shown to be effective in several simulations for both set point and trajectory tracking of the robot.

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