Comparison of Modeling Techniques for a Landing Gear

2010 ◽  
Author(s):  
Rebecca Margetts ◽  
Roger F. Ngwompo
Keyword(s):  
Block Diagram ◽  
Differential Algebraic Equations ◽  
Landing Gear ◽  
Algebraic Equations ◽  
Bond Graphs ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Wide Range ◽  
Modeling Techniques ◽  
Computational Errors

A wide range of modeling techniques is available to the engineer. The objective of this paper is to compare some typical modeling techniques for the simulation of a multi-domain mechatronic system. Usual dynamic modeling methods, such as block diagrams and iconic diagrams, can cause problems for the engineer. Differential algebraic equations (DAEs) and algebraic loops can significantly increase simulation times and cause numeric errors. Bond graphs are less common in industry, and are presented here as a method which allows the engineer to easily identify causal loops and elements in differential causality. These can indicate DAEs in the underlying equations. An aircraft landing gear is given as an example of a multi-domain system, and is modeled as a block diagram, an iconic diagram and as a bond graph. The time to construct the model, time to solve and problems faced by the analyst are presented. Bond graphs offer distinct advantages in terms of the ease of implementing algebraic equations and visibility of causality. The time taken to model a system can be significantly reduced and the results appear free from computational errors. Bond graphs are therefore recommended for this type of multi-domain systems analysis.

scholarly journals Assessment of Linearization Approaches for Multibody Dynamics Formulations

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Francisco González ◽  
Pierangelo Masarati ◽  
Javier Cuadrado ◽  
Miguel A. Naya
Keyword(s):  
Mechanical System ◽  
Multibody Dynamics ◽  
Equations Of Motion ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Practical Applications ◽  
Linearization Methods ◽  
Highly Nonlinear ◽  
Wide Range ◽  
The Way

Formulating the dynamics equations of a mechanical system following a multibody dynamics approach often leads to a set of highly nonlinear differential-algebraic equations (DAEs). While this form of the equations of motion is suitable for a wide range of practical applications, in some cases it is necessary to have access to the linearized system dynamics. This is the case when stability and modal analyses are to be carried out; the definition of plant and system models for certain control algorithms and state estimators also requires a linear expression of the dynamics. A number of methods for the linearization of multibody dynamics can be found in the literature. They differ in both the approach that they follow to handle the equations of motion and the way in which they deliver their results, which in turn are determined by the selection of the generalized coordinates used to describe the mechanical system. This selection is closely related to the way in which the kinematic constraints of the system are treated. Three major approaches can be distinguished and used to categorize most of the linearization methods published so far. In this work, we demonstrate the properties of each approach in the linearization of systems in static equilibrium, illustrating them with the study of two representative examples.

scholarly journals 1002 Aerodynamic noise reduction for aircraft landing gear

2009 ◽  
Vol 2009 (0) ◽  
pp. 321-322
Author(s):  
Kazuhide Isotani ◽  
Kenji Hayama ◽  
Akio Ochi ◽  
Toshiyuki Kumada
Keyword(s):  
Noise Reduction ◽  
Landing Gear ◽  
Aerodynamic Noise ◽  
Aircraft Landing ◽  
Aircraft Landing Gear

Nonlinear Transient Analysis of Aircraft Landing Gear Brake Whirl and Squeal

1995 ◽  
Author(s):  
Matt H. Travis
Keyword(s):  
Finite Element ◽  
Transient Analysis ◽  
Landing Gear ◽  
Friction Modeling ◽  
Explicit Integration ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Nonlinear Transient ◽  
Element Approach ◽  
Stiffness And Damping

Abstract The feasibility of computing non-linear transient finite element simulations of aircraft landing gear brake whirl and squeal is demonstrated and discussed. Methodology to conduct the high frequency brake transient analysis is developed using an explicit integration finite element approach. Results indicate the approach has the capability to simulate brake dynamic behavior in dynamometer and aircraft landing gear installations — thus enabling evaluation of modifications to braking systems that lead to more stable and robust designs. A simple multi-disk brake model is developed and described. Modeling techniques for including the dynamometer road wheel and runway in the simulations are given. Issues such as piston housing hydraulic fluid stiffness and damping effects, and parametric friction modeling are discussed.

Model-Based Design and Optimization of Passive Shoulder Exoskeletons

2021 ◽  
Author(s):  
Ali Nasr ◽  
Spencer Ferguson ◽  
John McPhee
Keyword(s):  
Elevation Angle ◽  
Differential Algebraic Equations ◽  
Joint Torque ◽  
Algebraic Equations ◽  
Joint Torques ◽  
Design And Optimization ◽  
Passive Mechanism ◽  
Wide Range ◽  
Passive Exoskeleton ◽  
Selection Of

Abstract To physically assist workers in reducing musculoskeletal strain or to develop motor skills for patients with neuromuscular disabilities, recent research has focused on Exoskeletons (Exos). Designing active Exos is challenging due to the complex human geometric structure, the human-Exoskeleton wrench interaction, the kinematic constraints, and the selection of power source characteristics. Because of the portable advantages of passive Exos, designing a passive shoulder mechanism has been studied here. The study concentrates on modeling a 3D multibody upper-limb human-Exoskeleton, developing a procedure of analyzing optimal assistive torque profiles, and optimizing the passive mechanism features for desired tasks. The optimization objective is minimizing the human joint torques. For simulating the complex closed-loop multibody dynamics, differential-algebraic equations (DAE)s of motion have been generated and solved. Three different tasks have been considered, which are common in industrial environments: object manipulation, over-head work, and static pointing. The resulting assistive Exoskeleton’s elevation joint torque profile could decrease the specific task’s human shoulder torque. Since the passive mechanism produces a specific torque for a given elevation angle, the Exoskeleton is not versatile or optimal for different dynamic tasks. We concluded that designing a passive Exoskeleton for a wide range of dynamic applications is impossible. We hypothesize that augmenting an actuator to the mechanism can provide the necessary adjustment torque and versatility for multiple tasks.

Study on Magneto-rheological Damper Control of Aircraft Landing Gear Based on LADRC

2021 ◽  
pp. 830-840
Author(s):  
Lei Dong ◽  
Zengqiang Chen ◽  
Mingwei Sun ◽  
Qinglin Sun ◽  
ZhenPing Yu
Keyword(s):  
Landing Gear ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Damper Control ◽  
Magneto Rheological
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