Numerical Simulation Of Aircraft Prescribed Maneuvers (original) (raw)

Multidisciplinary Simulation of the Maneuvering of an Aircraft

Engineering With Computers, 2001

A computational methodology for the simulation of the transient aeroelastic response of an unrestrained and flexible aircraft during high-G maneuvers is presented. The key components of this methodology are: (a) a three-field formulation for coupled fluid/structure interaction problems; (b) a second-order time-accurate and geometrically conservative flow solver for CFD computations on unstructured dynamic meshes; (c) a corotational finite element method for the solution of geometrically nonlinear and unrestrained structural dynamics problems; (d) a robust method for updating an unrestrained and unstructured moving fluid mesh; and (e) a second-order time-accurate staggered algorithm for time-integrating the coupled fluid/structure semi-discrete equations of motion. This computational methodology is illustrated with the simulation on a parallel processor of several three-dimensional high-G pullup maneuvers of the Langley Fighter in the transonic regime, using a detailed finite element aeroelastic model.

Generalized dynamic inversion for multiaxial nonlinear flight control

Proceedings of the 2011 American Control Conference, 2011

The nonlinear problem of aircraft trajectory tracking is tackled in the framework of multiple linear time-varying constrained control using the newly developed paradigm of generalized dynamic inversion. The time differential forms of the multiple constraints encapsulate the control objectives, and are inverted to obtain the reference trajectory-realizing control law. The inversion process utilizes the Moore-Penrose generalized inverse, and it predictably involves the problematic generalized inversion singularity. Thus, a singularity avoidance scheme based on a new type of dynamic scaling factors is introduced that guarantees asymptotically stable tracking and singularity avoidance. The steady state closed loop system allows for two inherently noninterfering control actions working towards a unified goal to exploit the aircraft's control authority over the entire state space. One control action is performed on the range space of the constraint generalized inverse matrix, and it works to impose the prescribed aircraft constrained dynamics. The other control action is performed on the complementary orthogonal nullspace of the constraint matrix, and it provides aircraft's global inner stability using a novel type of dynamically scaled nullprojection control Lyapunov functions. Numerical simulations of a multiaxial aircraft coordinated maneuver verify the efficacy of designing nonlinear flight control systems via this technique.

Studies on the Limitation of Fighter Aircraft Maneuver Caused by Automatic Control Design

In 1950, fighter aircraft were not able to make a shape maneuver in very high speed. Later, it became possible in 1980 caused by progress in technology. However, the maneuver was unstable. The control systems couldn’t perform perfectly and became very expensive when it applied to fighter aircraft. In this paper, we analyzed a non-linear and a linear model of fighter aircraft. We used Sweden JAS-39 fighter aircraft. As we know that this fighter aircraft can perform shape maneuver in supersonic speed during flight. To perform this kind maneuver, it needs good control system to assist pilot when “drive” the aircraft. Based on this problem, we design a linear controller based on a non-linear model of fighter aircraft and applied it to the dynamic non-linear model of fighter aircraft. Finally, we inspected it performance based on the angle of attack and the sideslip angle of fighter aircraft

STEERING OF FLEXIBLE MULTIBODY MODELS WITH APPLICATION TO THE SIMULATION OF MANEUVERING FLIGHT

Nonlinear flexible multibody dynamics enables the high-fidelity simulation of rotorcraft vehicles. In this work we focus on the problem of simulating extreme maneuvering flight conditions. In fact, limiting design factors such as maximum loads, vibrations, noise, etc. are encountered in the maneuvering flight case and at the boundaries of the flight envelope. The approach here proposed is based on a multiscale approach. A coarse level flight mechanics model of the vehicle is used for solving a generalized trajectory optimization problem that yields the flight path and the controls that fly the vehicle along it. This problem is formulated as an optimal control problem, but it is manageable at a reasonable computational cost since only a coarse model with few degrees of freedom is used. The computed controls are then used for steering a fine scale aeroelastic model which is based on finite element non-linear multibody dynamics. Matching of the trajectories flown by the two models is here obtained by means of parameter identification of the flight mechanics model. Selected critical rotorcraft maneuvers are analyzed in order to demonstrate the effectiveness of the proposed methodology.

Nonlinear aircraft modeling and controller design for target tracking

2011

In order to provide a novel perspective for videography of high speed sporting events, a highly capable trajectory tracking control methodology is developed for small scale Unmanned Aerial Vehicles (UAVs). The proposed controller combines dynamic inversion with linear tracking control using the internal model approach, and relies on a trajectory generating exosystem generated from available target training data. Three different aircraft models are presented each with increasing levels of complexity, in an effort to identify the simplest controller that yields acceptable performance. The dynamic inversion and linear tracking control laws are derived for each model, and simulation results are presented for tracking of elliptical and periodic trajectories.

A Computational Process Model of Basic Aircraft Maneuvering

2003

logistical challenges of working with the real operational military community. This paper will begin by setting the This paper describes a computational process model of context for the modeling through some background basic aircraft maneuvering. It is an embodied performance information on the STE. We then describe the model, implemented in ACT-R, that operates a Predator representations and processes built into the model and UAV synthetic task environment. The design of the model compare the model's performance to human performance. is borrowed from the Control and Performance Concept, a The paper concludes with a description of methodological widely taught technique for instrument flight, and from and implementation details that make this cognitive discussions with subject matter experts. Comparisons with modeling effort distinctive. human data show the model to be a good approximation to expert human performance, although the model shows more intra-maneuver variability. The paper concludes with Background on UAV STE a description of methodological and implementation details The core of the STE is a realistic simulation of the flight that make this cognitive modeling effort distinctive, dynamics of the Predator RQ-1A System 4 UAV. This core aerodynamics model has been used to train Air Force

Spatial motion of the aircraft manoeuvring to avoid moving obstacle

Journal of Theoretical and Applied Mechanics

In the paper, mathematical relationships which are used to describe kinematic variables of the aircraft-obstacles configuration and motion of the aircraft are presented. These define the base for the set of conditions enabling determination of the possibility and threat of collision. The second important aim of such a definition is creation of prerequisites for selection of an appropriate anti-collision manoeuvre, computation of reference signals and inequalities used as limitations on these signals in the automatic flight control process. Theoretical analysis is illustrated by an example of computer simulation of the flight of aircraft. Two anti-collision manoeuvres are studied in this experiment. The first one, performed in a vertical plane, consists in emergency climbing. The second one, performed in the horizontal plane, is shaped by three turns, each one of small radius, to go around the obstacle and then return to the previously realised flight path.

Simulation of Aircraft Manoeuvres based on Computational Fluid Dynamics

AIAA Atmospheric Flight Mechanics Conference, 2010

The use of computational fluid dynamics to generate and test aerodynamic data tables for flight dynamics analysis is described in this paper. The test case used is the Ranger 2000 fighter trainer for which flight test data is available. The generation of the tables is done using sampling and reconstruction to allow a large number of table entries to be generated at low computational cost. The testing of the tables is done by replaying, through a time accurate CFD calculation which features the moving control surfaces, manoeuvres and comparing the forces and moments against the tabular values. The manoeuvres are generated using a time optimal prediction code with the feasible solutions based on the tabular aerodynamics. The generated maneouvres are evaluated against flight data to show that they are qualitatively representative. Then the time accurate and tabular aerodynamics are compared, and as expected are in close agreement.

A study of flight manoeuvres for the PVTOL aircraft model

Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999

We study several flight control problems for the standard planar vertical take off and landing (PVTOL) flight control model, which has been developed as a simplified model for Harrier-like aircraft. In particular, we study the execution of a maneuver for which the aircraft is intended to follow a circular path in a vertical plane. We first formulate the problem as a nonlinear tracking control problem. Controllers are developed for two cases: a non-aggressive maneuver and an aggressive maneuver. We demonstrate the need to develop a controller that includes feedfowad terms in order to achieve aggressive maneuvering. We next formulate a related path following or maneuver regulation problem. A controller is developed for this case, and it is compared with a controller that solves the related output tracking problem. This comparison demonstrates the practical value of the maneuver regulation controller. Our approach throughout is to make use of nonlinear control theory, which is complicated by the non-minimum phase characteristics of the planar VTOL model.