Airship trim and stability analysis using bifurcation techniques
18 Jul 2016-pp 471-475
TL;DR: In this paper, bifurcation analysis of a full six degrees of freedom model of an airship is carried out both in unconstrained and constrained conditions, and typical modes of airship dynamics and regions of stable flights are identified via this analysis.
Abstract: In this paper, bifurcation analysis of a full six degrees of freedom model of an airship is carried out both in unconstrained and constrained conditions. Equations of motion of airship are first modified to a suitable form and a standard as well as constrained bifurcation analysis performed with respect to airship control and design parameters. Typical modes of airship dynamics and regions of stable flights are identified via this analysis. Loss of stability and mode responsible for onset of instability at critical parameter values are also identified.
Citations
More filters
TL;DR: The estimated nonlinear airship parameters are found to be consistent with the DATCOM parameter values which were used for open-loop simulation, which validates the proposed methodology and could be extended to estimateAirship parameters from real flight data.
Abstract: The prime focus of this work is to estimate stability and control derivatives of an airship in a completely nonlinear environment. A complete six degrees of freedom airship model has its aerodynamic model as nonlinear functions of angle of attack. Estimating the parameters of aerodynamic model in a nonlinear environment is challenging as it demands an exhaustive dataset that could cover the entire regime of operation of airship. In this work, data generation is achieved by simulating the mathematical model of airship for different trim conditions obtained from continuation analysis. The mathematical model is simulated using predicted parameter values obtained using DATCOM methodology. A modular neural network is then trained using back-propagation and Adam optimisation algorithm for each of the aerodynamic coefficients separately. The estimated nonlinear airship parameters are found to be consistent with the DATCOM parameter values which were used for open-loop simulation. This validates the proposed methodology and could be extended to estimate airship parameters from real flight data.
6 citations
Cites background from "Airship trim and stability analysis..."
...(14,15) and is presented in this section for the sake of completeness....
[...]
01 Jan 2019
TL;DR: The estimated nonlinear airship parameters are found to be consistent with the DATCOM parameters which were used for open-loop simulation in data generation phase and validates the proposed methodology and could be extended to estimateAirship parameters from real flight data.
Abstract: The prime objective of this work is to estimate stability and control derivatives of an airship. The complete, nonlinear mathematical model of aerial vehicles has its aero model as a nonlinear function of angle of attack. This along with the necessity for an exhaustive dataset complicates the estimation procedure. In this work, data are generated by simulating the mathematical model of airship for different trim conditions obtained from continuation analysis. A modular neural network is then trained using back-propagation and Adam optimization algorithm for each aerodynamic coefficient separately. The estimated nonlinear airship parameters are found to be consistent with the DATCOM parameters which were used for open-loop simulation in data generation phase. This validates the proposed methodology and could be extended to estimate airship parameters from real flight data.
2 citations
Cites background or methods from "Airship trim and stability analysis..."
...The trim and stability characteristics of the considered airship model were assessed in [12]....
[...]
...The detailed study on the mathematical modeling of the considered airship was carried out in [11], [12] and is presented in this section for the sake of completeness....
[...]
07 Jan 2019
1 citations
01 Jan 2022
TL;DR: In this paper , a motion mode analysis of the stratospheric airship is carried out, and the influence of key parameters such as the center of mass, center of buoyance, and aerodynamic stability moment on the motion mode of the airship are analyzed and summarized in detail.
Abstract: The stratospheric airship is taken as the research object, and the motion mode analysis of the stratospheric airship is carried out. The influence of key parameters such as the center of mass, the center of buoyance, and the aerodynamic stability moment on the motion mode of stratospheric airship are analyzed and summarized in detail. According to the simulation and analysis results, unlike high-speed and high-dynamic aircrafts such as airplanes, the motion modes of the stratospheric airship are hardly affected by the perturbation of aerodynamic stability moment; the perturbations of the vertical center of mass and the vertical center of buoyancy have a great influence on the pitch pendulum motion modes, and their parameter perturbations affect the frequency of the pitch pendulum motion and also the stability of the pitch pendulum motion; the axial mass center location perturbation not only changes the damping of pitch pendulum motion but also affects the frequency of the yaw motion attitude motion mode to a certain extent.
References
More filters
TL;DR: The sparsity of the discretized systems for the computation of limit cycles and their bifurcation points is exploited by using the standard Matlab sparse matrix methods.
Abstract: MATCONT is a graphical MATLAB software package for the interactive numerical study of dynamical systems. It allows one to compute curves of equilibria, limit points, Hopf points, limit cycles, period doubling bifurcation points of limit cycles, and fold bifurcation points of limit cycles. All curves are computed by the same function that implements a prediction-correction continuation algorithm based on the Moore-Penrose matrix pseudo-inverse. The continuation of bifurcation points of equilibria and limit cycles is based on bordering methods and minimally extended systems. Hence no additional unknowns such as singular vectors and eigenvectors are used and no artificial sparsity in the systems is created. The sparsity of the discretized systems for the computation of limit cycles and their bifurcation points is exploited by using the standard Matlab sparse matrix methods. The MATLAB environment makes the standard MATLAB Ordinary Differential Equations (ODE) Suite interactively available and provides computational and visualization tools; it also eliminates the compilation stage and so makes installation straightforward. Compared to other packages such as AUTO and CONTENT, adding a new type of curves is easy in the MATLAB environment. We illustrate this by a detailed description of the limit point curve type.
1,320 citations
Dissertation•
01 Oct 1990
68 citations
"Airship trim and stability analysis..." refers background in this paper
...Even though being a buoyancy, heavy aerodynamically inefficient vehicle, it is desired to arrive at optimized configuration of an airship, which utilizes maximum control from the aerodynamic control surfaces [1] even at low velocities other than the direct control from the engine for keeping airship in desired operating flight condition and for maneuvering....
[...]
08 Jan 2007
TL;DR: The state-of-the-art in the use of bifurcation and continuation methods for the analysis of aircraft trim and stability with a few illustrative examples are described.
Abstract: The bifurcation and continuation methodology has evolved over the last two decades into a powerful tool for the analysis of trim and stability problems in aircraft flight dynamics. Over the years, bifurcation methods have been employed to deal with a variety of problems in aircraft dynamics, such as predicting high angle of attack behavior, especially spin, and studying instabilities in rolling maneuvers. The bifurcation methodology has served as a tool for the design of flight control systems, and is promising to be a useful tool in the aircraft design, simulation, testing, and evaluation process. In the present paper, we describe the state-of-the-art in the use of bifurcation and continuation methods for the analysis of aircraft trim and stability with a few illustrative examples. Both the standard and extended bifurcation analysis procedures are discussed and typical results for instabilities in high-α flight and in inertia-coupled roll maneuvers are shown. This is followed by several problems in nonlinear flight dynamics where bifurcation and continuation methods have been fruitfully applied to yield effective solutions. Finally, the use of bifurcation theory to arrive at analytical instability criteria is demonstrated for the aircraft roll coupling and wing rock problems. 76 references have been cited in the text.
57 citations
01 Jan 1999
6 citations