Modification of a generalized inverse simulation technique for rotorcraft flight

2003 ◽  
Vol 217 (2) ◽  
pp. 61-73 ◽  
Author(s):  
D Anderson
Keyword(s):  
Degrees Of Freedom ◽  
Generalized Inverse ◽  
Simulation Models ◽  
Main Rotor ◽  
Algebraic Models ◽  
Inverse Algorithm ◽  
Inverse Simulation ◽  
Simulation Techniques ◽  
Current State ◽  
Simplifying Assumptions

Inverse simulation techniques have been employed for several years to analyse the manoeuvrability, operational suitability and conceptual design of helicopters. Much of the published work has used specially constructed (algebraic) models of the aircraft. Recently, integration methods have been used successfully with conventional simulation models, although with some important simplifying assumptions made regarding the dynamics of the main rotor, principally the omission of coupled lead/lag and rotorspeed degrees of freedom. This paper will present the current state-of-theart in helicopter inverse simulation—inserting a complete, validated, rigid-body rotorcraft model inside an integration-based algorithm. It is found that the additional rotor dynamics destabilize the inverse algorithm, resulting in severe oscillations in certain unconstrained states, most notably body pitch and roll angles. Analysis of the dynamics of the inverse system shows that these oscillations are manifest by lack of robustness in the inverse algorithm. Several new modifications to the inverse algorithm are shown to reduce these instabilities considerably.

scholarly journals Development of an inverse simulation method for the analysis of train performance

2017 ◽  
Vol 232 (5) ◽  
pp. 1295-1308 ◽  
Author(s):  
DJ Murray-Smith
Keyword(s):  
Initial Conditions ◽  
Simulation Models ◽  
Simulation Method ◽  
Time Instant ◽  
Tractive Force ◽  
Inverse Simulation ◽  
Simulation Techniques ◽  
Train Speed ◽  
Route Information ◽  
Input Variables

Conventional methods of computer-based simulation allow prediction of output variables, often as a function of time, for a given model of a physical system for a given set of initial conditions and input variables. In the case of train performance simulation models, the possible output variables include train speed or distance travelled, both expressed as functions of time. The corresponding input variables, also expressed as functions of time, are the tractive force or power levels for given train characteristics and route information such as gradients, track curvature and speed restrictions. Inverse simulation methods, on the other hand, allow selected model variables (such as the tractive force at any time instant) to be found from other specified model variables applied as input (such as the train speed or distance travelled versus time) for a given set of route conditions and train characteristics. The specific inverse simulation method presented in the paper is based on feedback principles. Illustrative results are used to verify this inverse simulation approach for train performance applications, and further cases are used to show that the inverse formulation provides an insight that is different from that obtained using more conventional forward simulation techniques.

scholarly journals Distributed Approaches to Supply Chain Simulation

2021 ◽  
Vol 31 (4) ◽  
pp. 1-31
Author(s):  
Navonil Mustafee ◽  
Korina Katsaliaki ◽  
Simon J. E. Taylor
Keyword(s):  
Supply Chain ◽  
State Of The Art ◽  
Discrete Event ◽  
Simulation Models ◽  
Event Simulation ◽  
Distributed Decision Making ◽  
Simulation Techniques ◽  
Current State ◽  
Trade Offs ◽  
Supply Chain Simulation

The field of Supply Chain Management (SCM ) is experiencing rapid strides in the use of Industry 4.0 technologies and the conceptualization of new supply chain configurations for online retail, sustainable and green supply chains, and the Circular Economy. Thus, there is an increasing impetus to use simulation techniques such as discrete-event simulation, agent-based simulation, and hybrid simulation in the context of SCM. In conventional supply chain simulation, the underlying constituents of the system like manufacturing, distribution, retail, and logistics processes are often modelled and executed as a single model. Unlike this conventional approach, a distributed supply chain simulation (DSCS) enables the coordinated execution of simulation models using specialist software. To understand the current state-of-the-art of DSCS, this paper presents a methodological review and categorization of literature in DSCS using a framework-based approach. Through a study of over 130 articles, we report on the motivation for using DSCS, the modelling techniques, the underlying distributed computing technologies and middleware, its advantages and a future agenda, and also limitations and trade-offs that may be associated with this approach. The increasing adoption of technologies like Internet-of-Things and Cloud Computing will ensure the availability of both data and models for distributed decision-making, which is likely to enable data-driven DSCS of the future. This review aims to inform organizational stakeholders, simulation researchers and practitioners, distributed systems developers and software vendors, as to the current state-of-the art of DSCS, and which will inform the development of future DSCS using new applied computing approaches.

Effects of Suspension Design on the Attitudes of a Car during Braking and Acceleration

1973 ◽  
Vol 187 (1) ◽  
pp. 787-794
Author(s):  
J. R. Ellis
Keyword(s):  
Steady State ◽  
Linear Systems ◽  
Degrees Of Freedom ◽  
Coupled Systems ◽  
Two Degrees Of Freedom ◽  
Simulation Techniques ◽  
Non Linear ◽  
Non Linear Systems ◽  
Effort Distribution

Two degrees of freedom models of a car are employed to demonstrate the effects of the suspension derivative ∂ x/∂ z on the pitch and bounce attitudes during braking or accelerating. The work equation is employed to show that brake effort distribution between the axles has a significant effect on the attitudes when anti-dive suspension characteristics are utilized. The steady-state positions in both pitch and bounce are developed for linear systems of typical suspensions that may be either standard or coupled systems. Non-linear systems are considered using simulation techniques. A description of some simulation circuits is contained in an appendix.

Vehicle-Terrain Interaction Simulation With Parallelized Multiscale Moving Soil Patch Model

2019 ◽  
Author(s):  
Hiroki Yamashita ◽  
Guanchu Chen ◽  
Yeefeng Ruan ◽  
Paramsothy Jayakumar ◽  
Hiroyuki Sugiyama
Keyword(s):  
Interaction Model ◽  
Simulation Models ◽  
Vehicle Performance ◽  
Vehicle Simulation ◽  
Full Vehicle ◽  
Simulation Techniques ◽  
Patch Technique ◽  
Dynamics Models ◽  
Hierarchical Multiscale ◽  
Soil Patch

Abstract Although many physics-based off-road mobility simulation models are proposed and utilized for vehicle performance evaluation as well as for understanding of tire-soil interaction problems, full vehicle simulation on deformable terrain requires addressing the computational complexity associated with the large dimensional physics-based terrain dynamics models for practical use. This paper, therefore, presents a hierarchical multiscale tire-soil interaction model that is fully integrated into parallelized off-road mobility simulation framework. In particular, a co-simulation procedure is developed for full vehicle simulation with multiscale terrain dynamics models by exploiting the moving soil patch technique. To this end, a detailed off-road vehicle simulation model is divided into five subsystems: a multibody vehicle subsystem and four tire-soil subsystems composed of nonlinear FE tires and multiscale moving soil patches. The tire-soil subsystems are interfaced with the vehicle subsystem by MPI through force-displacement coupling. It is demonstrated that the proposed framework allows for alleviating computational intensity of a full vehicle simulation that involves complex hierarchical multiscale terrain dynamics models by effectively distributing computational loads with co-simulation techniques.

SUPPORTING DECISION-MAKING IN SOFTWARE ENGINEERING WITH PROCESS SIMULATION AND EMPIRICAL STUDIES

2003 ◽  
Vol 13 (05) ◽  
pp. 531-545 ◽  
Author(s):  
IOANA RUS ◽  
MICHAEL HALLING ◽  
STEFAN BIFFL
Keyword(s):  
Decision Making ◽  
Quality Assurance ◽  
Software Engineering ◽  
Process Simulation ◽  
Empirical Studies ◽  
Empirical Knowledge ◽  
Simulation Techniques ◽  
Current State ◽  
Parameter Variations ◽  
Support Decision Making

Decision-making is a complex and important task in software engineering. The current state-of-the-practice is rather non-systematic as it typically relies upon personal judgment and experience without using explicit models. Empirical studies can help but they are costly to conduct and, to some extent, context dependent. Typically it is not efficient or even possible to conduct empirical studies for a large number of context parameter variations. Process simulation offers decision support as well, but currently suffers from a lack of empirical knowledge on the determinants of underlying system dynamics. In this paper we present an assessment of empirical knowledge and simulation techniques for the area of quality assurance planning. There is a strong interdependency between process simulation and empirical models for decision-making in this area: (a) profound empirical knowledge enables process simulation to support decision-making, and (b) the analysis of simulation results can point out situations and factors for which conducting empirical studies would be most worthwhile. This paper discusses critically some of the most important challenges for decision-making in the area of quality assurance planning.

Simulation of the construction of cable-stayed bridges

1998 ◽  
Vol 25 (3) ◽  
pp. 490-499 ◽  
Author(s):  
Dulcy M Abraham ◽  
Daniel W Halpin
Keyword(s):  
Computer Simulation ◽  
Simulation Modeling ◽  
Simulation Models ◽  
Interstate Highways ◽  
Simulation Techniques ◽  
Pedestrian Bridges ◽  
Cantilever Construction ◽  
Fertile Area ◽  
Computer Simulation Techniques ◽  
Cable Stayed Bridges

Cable-stayed bridges are ideal for spanning natural barriers of wide rivers, deep valleys, or ravines, and for pedestrian bridges crossing wide interstate highways. Modern construction of cable-stayed bridges makes use of the segmental balanced cantilever techniques and involves many repetitive cycles of placing the concrete segments (both cast-in-place and precast) and supporting cables. It provides a fertile area for the application of computer simulation techniques for the planning and analysis of the process, particularly for studying the interaction of resources used in the construction phase and also for assessing the productivity of the construction processes. This paper employs MicroCYCLONE, a microcomputer-based simulation program, for the modeling and simulation of the construction of two cable-stayed bridges: the Dame Point Bridge in the state of Florida, U.S.A., and the Tsukuhara Bridge in Hyuougo, Japan. The paper will also provide a brief explanation of the suspended long traveler method used on the Tsukuhara Bridge, the simulation models developed to analyze the construction processes, and the results of sensitivity analyses.Key words: simulation, modeling, construction, cable-stayed bridges, resources, productivity, balanced cantilever construction.

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