scholarly journals Stability Analysis of a Helicopter with an External Slung Load System

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Kary Thanapalan
Keyword(s):  
Stability Analysis ◽  
Nonlinear System ◽  
External Load ◽  
Numerical Results ◽  
Uncertain Nonlinear System ◽  
Cascade Connection ◽  
The Stability ◽  
Lyapunov Second Method

This paper describes the stability analysis of a helicopter with an underslung external load system. The Lyapunov second method is considered for the stability analysis. The system is considered as a cascade connection of uncertain nonlinear system. The stability analysis is conducted to ensure the stabilisation of the helicopter system and the positioning of the underslung load at hover condition. Stability analysis and numerical results proved that if desired condition for the stability is met, then it is possible to locate the load at the specified position or its neighbourhood.

Stability and Vibrations of Geometrically Nonlinear Cylindrically Orthotropic Circular Plates

1984 ◽  
Vol 51 (2) ◽  
pp. 354-360 ◽  
Author(s):  
D. Shilkrut
Keyword(s):  
Stability Analysis ◽  
Qualitative Methods ◽  
Dynamic Method ◽  
Numerical Results ◽  
Geometrically Nonlinear ◽  
Circular Plates ◽  
Different Types ◽  
The Stability ◽  
Thermal Influence ◽  
Cylindrically Orthotropic

The stability analysis of axisymmetrical equilibrium states of geometrically nonlinear, orthotropic, circular plates that are deformed by multiparameter loading, including thermal influence, is presented. The dynamic method (method of small vibrations) is used to accomplish this purpose. The behavior of the plate in different cases is revealed. In particular, it is shown that two different types of snapping processes can occur. The values of frequencies of small eigenvibrations from various cases have been calculated. These investigations are realized by numerical and qualitative methods. Here only the numerical results are presented.

scholarly journals Stability analysis of cylindrical shells subjected to complex loads

2001 ◽  
Vol 23 (4) ◽  
pp. 247-256
Author(s):  
Ngo Huong Nhu
Keyword(s):  
Cylindrical Shell ◽  
Stability Analysis ◽  
Composite Shell ◽  
Laminated Composite ◽  
Numerical Results ◽  
Load Pressure ◽  
Combined Loads ◽  
Analytical Result ◽  
The Stability ◽  
Good Agreement

The paper deals with stability analysis of shell on the basis FEM via Castem 2000. The numerical results of stability problems of cylinders subjected to different loads as compress load, pressure, concentrated and combined loads are compared with analytical result and give a good agreement. The influence of changing radius of the cylindrical shell on the unstable forms and the influence of angles of fibers on unstable behaviour of laminated composite shell are considered. Numerical results and corresponding programs by languages Gibian given in the paper to realize software Castem 2000 can be applied in the design and in the stability analysis of the shell with more complex conditions

scholarly journals Three-dimensional modeling and time-delay stability analysis for robotics docking simulation

2019 ◽  
Vol 233 (14) ◽  
pp. 5438-5455
Author(s):  
Prateek Sazawal ◽  
Daniel Choukroun ◽  
Heike Benninghoff ◽  
Eberhard Gill
Keyword(s):  
Stability Analysis ◽  
Time Delay ◽  
Nonlinear System ◽  
Contact Force ◽  
System Model ◽  
Model Parameters ◽  
Force Model ◽  
Hardware In The Loop ◽  
Contact Force Model ◽  
The Stability

Hardware-in-the-loop simulations of two interacting bodies are often accompanied by a time delay. The time delay, however small, may lead to instability in the hardware-in-the-loop system. The present work investigates the source of instability in a two spacecraft system model with a time-delayed contact force feedback. A generic compliance-device-based contact force model is proposed with elastic, viscous, and Coulomb friction effects in three dimensions. A 3D nonlinear system model with time delay is simulated, and the effect of variations in contact force model parameters is studied. The system is then linearized about a nominal state to determine the stability regions in terms of parameters of the spring-dashpot contact force model by the pole placement method. Furthermore, the stability analysis is validated for the nonlinear system by energy observation for both the stable and unstable cases.

scholarly journals Solving Volterra Integrodifferential Equations via Diagonally Implicit Multistep Block Method

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Nur Auni Baharum ◽  
Zanariah Abdul Majid ◽  
Norazak Senu
Keyword(s):  
Stability Analysis ◽  
Numerical Solution ◽  
Numerical Method ◽  
Numerical Computation ◽  
Numerical Solutions ◽  
Numerical Results ◽  
Integrodifferential Equations ◽  
Block Method ◽  
The Stability ◽  
Predictor Corrector

The performance of the numerical computation based on the diagonally implicit multistep block method for solving Volterra integrodifferential equations (VIDE) of the second kind has been analyzed. The numerical solutions of VIDE will be computed at two points concurrently using the proposed numerical method and executed in the predictor-corrector (PECE) mode. The strategy to obtain the numerical solution of an integral part is discussed and the stability analysis of the diagonally implicit multistep block method was investigated. Numerical results showed the competence of diagonally implicit multistep block method when solving Volterra integrodifferential equations compared to the existing methods.

Stability Analysis of Spools with Imperfect Sealing Gap Geometries

2021 ◽  
Author(s):  
Rituraj Rituraj ◽  
Rudolf Scheidl
Keyword(s):  
Stability Analysis ◽  
Analytical Model ◽  
Ritz Method ◽  
Lateral Force ◽  
Graphical Analysis ◽  
Numerical Results ◽  
Design Parameters ◽  
Analytical Expression ◽  
Parametric Studies ◽  
The Stability

Spools in hydraulic valves are prone to sticking caused by unbalanced lateral forces due to geometric imperfections of their sealing lands. This sticking problem can be related to the stability of the coaxial spool position. Numerical methods are commonly used to study this behaviour. However, since several parameters can influence the spool stability, parametric studies become significantly computationally expensive and graphical analysis of the numerical results in multidimensional parameter space becomes difficult. To overcome this difficulty, in this work, an analytical approach for studying the stability characteristics of the spool valve is presented. A Rayleigh-Ritz method is used for solving the Reynolds equation in an approximate way in order to determine an analytical expression for the lateral force on the sealing lands. This analytical expression allows stability analysis of the spool via analytical means which finally results in the expression of critical axial velocity which demarcates the regions of stable behaviour. Simplicity of the expression allows an immediate insight into the role of design parameters in the stability of the spool. To verify the analytical model, a numerical model for spool dynamics is developed in this work and the numerical results are found to match the analytical model in terms of the stability behaviour of the spool.

Stability Analysis of High-Performance Drones With Suspended Payloads

2019 ◽  
Author(s):  
Samantha Hoang ◽  
Yifeng Liu ◽  
Alberto Aliseda ◽  
I. Y. Shen
Keyword(s):  
Stability Analysis ◽  
Nonlinear System ◽  
High Performance ◽  
Initial Conditions ◽  
Wind Disturbance ◽  
External Disturbances ◽  
Nonlinear Simulations ◽  
Linearized System ◽  
Payload Mass ◽  
The Stability

Abstract This paper studies the stability of a system consisting of a drone with a heavy payload through both linear stability analysis and nonlinear simulations. The stability is studied with respect to two payload parameters: the length of the arm the payload is suspended from and the mass of the payload. Linearizing the drone-payload system around vertical flight results in a linearized system that is marginally stable with five negative, real eigenvalues and seven zero-eigenvalues. The presence of seven zero-eigenvalues makes it difficult to predict the stability of the nonlinear system so nonlinear simulations are completed to understand how the drone-payload system reacts to external disturbances. To directly study the severity of the nonlinear system’s instability, the system is subjected to an initial, one-second wind disturbance that induces different initial conditions on the system. The results of the nonlinear simulations indicate that the presence of a suspended payload will always cause the drone-payload system to be unstable. Both an increase in the length of the payload arm and the payload mass will individually increase the deviation of the system from the expected path.

Fuzzy Based Model Predictive Control for Uncertain Nonlinear System

2011 ◽  
Vol 383-390 ◽  
pp. 2404-2410
Author(s):  
Li Xu ◽  
Fei Liu
Keyword(s):  
Nonlinear System ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Fuzzy Model ◽  
Linear Matrix ◽  
Uncertain Nonlinear System ◽  
Predictive Controller ◽  
The Stability ◽  
Takagi Sugeno ◽  
Parameter Dependent

In this paper, a model predictive control (MPC) scheme is investigated for uncertain nonlinear system with time delay and input constraint. First, the Takagi-Sugeno (T-S) fuzzy model is used to approximate the dynamics of nonlinear processes and the parallel distributed compensation (PDC) controllers which are parameter dependent and mirror the structure of the T-S plant model are proposed. Then a novel feedback PDC predictive controller obtained from the linear matrix inequality (LMI) solutions which can guarantee the stability of the closed-loop overall fuzzy system is put forward. Finally, a numerical example is provided to demonstrate the effectiveness and feasibility of the proposed method.

Stability analysis for a rotor system in a magnetically suspended control and sensitive gyroscope with the Lorentz force magnetic bearing rotation

2018 ◽  
Vol 233 (5) ◽  
pp. 548-557 ◽  
Author(s):  
Changfeng Xia ◽  
Yuanwen Cai ◽  
Yuan Ren
Keyword(s):  
Stability Analysis ◽  
Nonlinear System ◽  
Lorentz Force ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Complex Frequency ◽  
Analysis Method ◽  
Double Frequency ◽  
Bode Diagram ◽  
The Stability

In order to intuitively and conveniently analyse the stability of a rotor system in a magnetically suspended control and sensitive gyroscope with the rotation of a Lorentz force magnetic bearing, this study proposes a stability analysis method on the basis of a pseudo-linear equivalent transformation and extended double-frequency Bode diagram. The working principle of the rotor system is presented, and the dynamic model for this system that considers the Lorentz force magnetic bearing rotation is established. The established real-coefficient two-input–two-output nonlinear system is transferred into a complex-coefficient single-input–single-output nonlinear system through variable reconstruction. Based on the complex frequency shift characteristics of Laplace transformation, the time-varying nonlinear system is converted into a pseudo-linear system. In accordance with the relationship between a Nyquist curve and a Bode diagram, the extended double-frequency Bode diagram method is proposed to analyse the stability of a non-minimum phase system with integral items. Simulation and experimental results demonstrate the correctness of the proposed analysis method.

Sign in / Sign up

Export Citation Format

Share Document