Aircraft Maneuver Design using Bifurcation Analysis and Nonlinear Control Techniques
04 Jan 2011-
TL;DR: In this paper, a constrained bifurcation analysis based procedure is used to determine the level flight and level turn steady states for an F-18/HARV model, and a Nonlinear Dynamic Inversion (NDI) based controller is designed to perform the closed loop simulation of a constant speed, level, coordinated turn maneuver from a straight and level flight to the maximum sustained turn rate flight conditions.
Abstract: In this paper, we present a methodology using bifurcation analysis and nonlinear control techniques to design aircraft maneuvers. As an illustrative example, maneuvering of an aircraft from a steady level flight to level turn flights is attempted. A constrained bifurcation analysis based procedure is used to determine the level flight and level turn steady states for an F-18/HARV model. Using the available states from bifurcation analysis results as setpoints, a Nonlinear Dynamic Inversion (NDI) technique based controller is designed to perform the closed loop simulation of a constant speed, level, coordinated turn maneuver from a straight and level flight to the maximum sustained turn rate flight conditions. Successful implementation of the technique while satisfying the prescribed constraints shows usefulness of the approach.
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TL;DR: A new longitudinal short-period deep-stall model is established in the presence of time-varying distributed delays and an improved finite-time control law is developed to avoid the singularity problem in traditional finite- time control.
Abstract: In this paper, the problem of deep-stall recovery will be studied for the aircraft without longitudinal static stability. A new longitudinal short-period deep-stall model is established in the presence of time-varying distributed delays. Based on bifurcation analysis method, the effects of actuator fault on deep stall are analyzed in depth. Considering the system uncertainty, actuator fault, input saturation and unsteady disturbance, a finite-time prescribed performance deep-stall recovery law is designed according to the bifurcation analysis results. Further, to avoid the singularity problem in traditional finite-time control, an improved finite-time control law is developed. Stability of the closed-loop system is proved by common Lyapunov functional method. And simulations are given to illustrate the validity of the proposed deep-stall recovery control scheme.
9 citations
Cites methods from "Aircraft Maneuver Design using Bifu..."
...Bifurcation analysis technology has been widely used in the analysis of aircraft dynamic characteristics, and was applied to the design of flight control laws [9]–[11]....
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TL;DR: In this study, the stall point and bifurcation point are confirmed using the b ifurcation analysis, and the results show that the aircraft will stall when excessive elevator movement is commanded.
Abstract: Loss of control (LOC) is considered one of the leading causes of fatal aircraft accidents worldwide. Reducing LOC is critical to improve flight safety. Although it is still vaguely defined, LOC is generally associated with a flight state that is outside the safety envelope, with nonlinear influences of aircraft dynamics and incorrect handling by the flight crew. We have studied how nonlinear factors and pilot operations contribute to LOC. In this study, the stall point and bifurcation point are confirmed using the bifurcation analysis, and the results show that the aircraft will stall when excessive elevator movement is commanded. Moreover, even though there may be an equilibrium state in one of the elevator deflections, the flight state may still be outside the flight safety envelope. When the flight state is near the edge of the flight safety envelope, the strategy to regulate the elevator deflection is super-sensitive, and a slight change in the elevator deflection may contribute to a flight state outside the safety envelope. To solve this issue, the differential manifold theory is introduced to determine the safety envelope. Examples are provided using NASA’s generic transport model.
5 citations
Cites background from "Aircraft Maneuver Design using Bifu..."
...Therefore, it will be helpful in guiding operation, reducing the accidents attributed to LOC along with the loss of life and the large financial costs (Khatri and Sinha, 2011; Engelbrecht et al., 2012)....
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17 Dec 2020
TL;DR: In this paper, a backstepping control is designed to autonomously execute the high alpha cobra maneuver under significant lateral c.g. shift, and the simulation results show the maneuver performance under lateral asymmetry to be almost the same as that without any asymmetry.
Abstract: Asymmetric release of payload or partial damage of wing shifts the center-of-gravity (c.g.) of a fighter aircraft to new positions resulting in a highly coupled and nonlinear asymmetric dynamics. Since controlling the aircraft becomes much more challenging when it tries to perform some high alpha maneuver with such lateral asymmetry, implementation of nonlinear control becomes mandatory for the safety of the aircraft. In the present paper, the highly coupled asymmetric dynamics is first converted to the strict feedback form and thereafter a backstepping control is designed to autonomously execute the high alpha cobra maneuver under significant lateral c.g. shift. The simulation results show the maneuver performance under lateral asymmetry to be almost the same as that without any asymmetry.
1 citations
16 Jul 2021
TL;DR: In this article, a backstepping control scheme is implemented to execute high alpha-first maneuver under significant lateral center-of-gravity shift, which is almost similar as that without any asymmetry.
Abstract: Asymmetric dynamics of a combat aircraft becomes highly coupled when center-of-gravity (c.g.) of an aircraft shifts to new position because of either partial wing damage or asymmetric release of store. It becomes difficult for an aircraft to execute high angle maneuvering under asymmetric center- of-gravity shift as nonlinearity and dynamics get more complex, under such situation implementation of nonlinear control becomes inevitable. In the present study, dynamics is first converted into strict feedback form and then backstepping control scheme is implemented to execute high alpha herbst maneuver under significant lateral center-of- gravity shift. The simulation result obtained by the present study advocates the maneuver performance under lateral asymmetry to be almost similar as that without any asymmetry.
References
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01 Jan 2007
1,532 citations
01 Jan 1997
TL;DR: This is a guide to the software package AUTO for continuation and bifurcation problems in ordinary differential equations and the development of HomCont has much benefitted from various pieces of help and advice from, among others, W. W. Norton.
Abstract: Preface This is a guide to the software package AUTO for continuation and bifurcation problems in ordinary differential equations. graphics program PLAUT and the pendula animation program. An earlier graphical user interface for AUTO on SGI machines was written by Taylor & Kevrekidis (1989). Special thanks are due to Sheila Shull, California Institute of Technology, for her cheerful assistance in the distribution of AUTO over a long period of time. Over the years, the development of AUTO has been supported by various agencies through the California Institute of Technology. Work on this updated version was supported by a general research grant from NSERC (Canada). The development of HomCont has much benefitted from various pieces of help and advice from, among others, W. This manual uses the following conventions. command This font is used for commands which you can type in. PAR This font is used for AUTO parameters. filename This font is used for file and directory names. variable This font is used for environment variable. site This font is used for world wide web and ftp sites. function This font is used for function names.
1,417 citations
TL;DR: In this article, the authors discuss the use of nonlinear dynamic inversion in the design of a flight control system for a Superman aircraft and compare it with a more conventional, gain-scheduled system and yield better performance in terms of lateral acceleration, sideslip, and control deflections.
Abstract: Nonlinear dynamic inversion affords the control system designer a straightforward means of deriving control laws for nonlinear systems. The control inputs are used to cancel unwanted terms in the equations of motion using negative feedback of these terms. In this paper, we discuss the use of nonlinear dynamic inversion in the design of a flight control system for a Supermaneuvera ble aircraft. First, the dynamics to be controlled are separated into fast and slow variables. The fast variables are the three angular rates and the slow variables are the angle of attack, sideslip angle, and bank angle. A dynamic inversion control law is designed for the fast variables using the aerodynamic control surfaces and thrust vectoring control as inputs. Next, dynamic inversion is applied to the control of the slow states using commands for the fast states as inputs. The dynamic inversion system was compared with a more conventional, gain-scheduled system and was shown to yield better performance in terms of lateral acceleration, sideslip, and control deflections.
579 citations
TL;DR: In this article, a new approach for analyzing nonlinear and high-a dynamic behavior and stability of aircraft is presented, which involves the application of bifurcation analysis and catastrophe theory methodology to specific phenomena such as stall, departure, spin entry, flat and steep spin, nose slice, and wing rock.
Abstract: A new approach is presented for analyzing nonlinear and high-a dynamic behavior and stability of aircraft. This approach involves the application of bifurcation analysis and catastrophe theory methodology to specific phenomena such as stall, departure, spin entry, flat and steep spin, nose slice, and wing rock. Quantitative results of a global nature are presented, using numerical techniques based on parametric continuation. It is shown how our methodology provides a complete representation of the aircraft equilibrium and bifurcation surfaces in the state-control space, using a rigid body model with aerodynamic controls. Also presented is a particularly useful extension of continuation methods to the detection and stability analysis of stable attracting orbits (limit cycles). The use of this methodology for understanding high-a phenomena, especially spin-related behavior, is discussed. RENDS in fighter aircraft design over the past few decades have resulted in configuration s noted for their high speed and performance capability. The cost of achieving this capability has been a drastic, often fatal loss of positive control of the aircraft as the pilot operates at or near the extremes of the flight envelope. This is especially true for aircraft motion at high angles of attack (a), where large deviations both in the state and control variables limits the application of the usual linearized analysis techniques. There is a conspicuous lack of techniques for analyzing global stability and large maneuver response of aircraft. While certain phenomena (e.g., roll coupling) have been analyzed in an isolated manner, there exists a clear need for a unified approach to analyze systematically global aircraft behavior at high a.
205 citations
TL;DR: Bifurcation theory has been used to study the nonlinear dynamics of the F-14, and a simple feedback control system was designed to eliminate the wing rock and spiral divergence as mentioned in this paper.
Abstract: Bifurcation theory has been used to study Ihe nonlinear dynamics of the F-14. An 8 degree-of-freedom model
that does not include the control system present in operational F-14's has been analyzed. The aerodynamic
model, supplied by NASA, includes nonlinearlties as functions of the angles of attack and sideslip, the rotation
rate about the velocity vector, and the elevator deflection. A continuation method has been used to calculate
the steady states of the F -14 as continuous functions of the elevator deflection. Bifurcations of these steady states
have been used to predict the onset of wing rock, spiral divergence, and jump phenomena that cause the aircraft
to enter a spin. A simple feedback control system was designed to eliminate the wing rock and spiral divergence
instabilities. The predictions were verified with numerical simulations.
147 citations