Terrain Gridding Using a Stochastic Weighting Function

2011 ◽  
Author(s):  
Rui Ma ◽  
John B. Ferris
Keyword(s):  
Weighting Function ◽  
Grid Node ◽  
Vehicle Modeling ◽  
Vehicle Simulation ◽  
Median Distance ◽  
Tire Modeling ◽  
Grid Nodes ◽  
Definition Of ◽  
Inverse Distance ◽  
Vertical Height

The development of new stochastic terrain gridding methods are necessitated by new tire and vehicle modeling applications. Currently, grid node locations in the horizontal plane are assumed to be known and only the uncertainty in the vertical height estimates is modeled. This work modifies the current practice of weighting the importance of a particular measured data point (the terrain height at some horizontal location) by the inverse distance between the grid node and that point. A new weighting function is developed to account for the error in the horizontal position of the grid nodes. The geometry of the problem is described and the probability distribution is developed in steps. Although the solution cannot be determined in closed form, an estimate of the median distance is developed within 1% error. This more complete stochastic definition of the terrain can then be used for advanced tire modeling and vehicle simulation.

Tire Modeling for Off-Road Vehicle Simulation

2004 ◽  
Author(s):  
Chi-Ying Liang ◽  
R. Wade Allen ◽  
Theodore J. Rosenthal ◽  
Jeffrey P. Chrstos ◽  
Patrick Nunez
Keyword(s):  
Road Vehicle ◽  
Vehicle Simulation ◽  
Tire Modeling

A Three-Dimensional Dynamic Tire Model for Vehicle Dynamic Simulations

2000 ◽  
Vol 28 (2) ◽  
pp. 72-95 ◽  
Author(s):  
B. G. Kao
Keyword(s):  
Three Dimensional ◽  
Rigid Bodies ◽  
Dynamic Responses ◽  
Tire Model ◽  
Vehicle Dynamic ◽  
Vehicle Simulation ◽  
Modeling Concept ◽  
Tire Modeling ◽  
Tire Models ◽  
Force Calculation

Abstract Traditional multibody dynamic (MBD) tire models concentrate on the tire patch force development and the tire in-plane characteristics. The tire lateral dynamics and nonlinear effects caused by the tire compliances during rough terrain driving and severe maneuvers are mostly neglected in vehicle analytical simulations. The tire finite element models, though capable of dealing with these phenomena, are basically not designed for quick vehicle dynamic evaluations. A simple three-dimensional (3-D) MBD tire model for full vehicle performance and maneuvering simulations over various road surfaces is therefore desirable for the ever expanding analysis capabilities and the improved accuracy of the computer-aided vehicle design analysis. In this paper a tire modeling concept to extend the in-plane dynamic tire model to full 3-D tire dynamics is proposed. Essentially, this tire model divides the traditional tire/wheel system model into three elements: two rigid bodies representing the wheel mass/inertia and the tire tread mass/inertia, and a spring/damper representing the sidewall visco-elasticity. Thus, 6 degrees-of-freedom (DOFs) are added for each tire over traditional tire models. Using any existing tire patch force calculation model, this proposed model can be used to simulate full 3-D dynamic responses of a vehicle. To implement this model, techniques to extract the nonlinear spring rates of the sidewalls and to enhance the tire patch force calculations over uneven terrains are explained in this paper. Results of the vehicle simulation using this tire model were compared with measured field data. They showed that this tire modeling concept yields a practical representation for tire 3-D nonlinear dynamic characteristics.

scholarly journals MAPPING OF ALGAE RICHNESS USING SPATIAL DATA INTERPOLATION

2015 ◽  
Vol XL-7/W3 ◽  
pp. 1005-1008 ◽  
Author(s):  
F. O. Tapia-Silva ◽  
O. E. Hernández-Cervantes ◽  
M. I. Vilchis-Alfaro ◽  
A. Sentíes ◽  
K. M. Dreckmann
Keyword(s):  
Spatial Data ◽  
Spatial Scales ◽  
Algal Species ◽  
Environmental Variable ◽  
Coastal Zones ◽  
External Variable ◽  
Validation Technique ◽  
Definition Of ◽  
Leave One Out ◽  
Inverse Distance

This work describes the generation of a database of algal species richness at two spatial scales – regional (Gulf of Mexico and the Caribbean) and global (coastal zones). As a first approach to the definition of the temporal variability, and to produce the corresponding maps, a previously published decision tree is used in order to select the best spatial interpolation technique according to the characteristics of the spatial data. The methods presented are ordinary Kriging (since no relationship exists with any environmental variable that could function as an external variable) and inverse distance squared, for comparative purposes. The methods to generate the spatial layers are evaluated using the leave-one-out cross validation technique. Although the evaluation did not find a large correspondence (in terms of linear regression) between the interpolated and measured values, it was possible to capture the spatial variability of the process and produce the cartography of this variable, with which future ecological analyses can be performed.

scholarly journals Design and Implementation of a Co-Simulation Framework for Testing of Automated Driving Systems

2020 ◽  
Author(s):  
Demin Nalic ◽  
Aleksa Pandurevic ◽  
Arno Eichberger ◽  
Branko Rogic
Keyword(s):  
Test Procedure ◽  
Flow Simulation ◽  
Simulation Software ◽  
Simulation Framework ◽  
Automated Driving ◽  
Test Procedures ◽  
Vehicle Simulation ◽  
Design And Implementation ◽  
Definition Of ◽  
Test Scenarios

The increasingly used approach of combining different simulation software for testing of automated driving systems (ADS) increases the need for potential and convenient software designs. Recently developed co-simulation platforms (CSP) provide the possibility to cover the high demand on testing kilometres for ADS by combining vehicle simulation with traffic flow simulation software (TFSS) environments. Having chosen a suitable CSP rises up the question how the test procedures should be defined and constructed and what are the relevant test scenarios. Parameters of the ADS in vehicle simulation, traffic parameter in TFSS and combination of all these can be used for the definition of test scenarios. Thus the automation of a process, consisting of vehicle and traffic parameters and a suitable CSP, a test procedure for ADS should be well designed and implemented. This paper presents the design and implementation of a complex co-simulation framework for virtual ADS testing combining IPG CarMaker and PTV Vissim.

scholarly journals TRT EVO: Advances in real-time thermodynamic tire modeling for vehicle dynamics simulations

2018 ◽  
Vol 233 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Flavio Farroni ◽  
Michele Russo ◽  
Aleksandr Sakhnevych ◽  
Francesco Timpone
Keyword(s):  
Thermal Model ◽  
Thermal State ◽  
Three Dimensional ◽  
Research Activity ◽  
Frictional Performance ◽  
Tire Modeling ◽  
Definition Of ◽  
Dynamics Simulations ◽  
Pressure Stress ◽  
Heat Exchanges

Vehicle performances, especially in motorsport, are deeply affected by tire behavior and in particular by tire compound proper working conditions. In this research activity, a series of innovations have been introduced on the Thermo Racing Tire (a physical-analytical tire thermal model, based on Fourier’s law of heat transfer applied to a three-dimensional domain) in order to take into account all the main aspects actively involved in the thermal behavior of the tire, as the presence of exhausted gases eventually impacting at the rear axle and the inhomogeneous distribution of local variables (pressure, stress and sliding velocity) within the contact patch, caused in example by the tire camber angle. The new model developed considers the presence of the sidewalls, actively involved in the convective heat exchanges, respectively, with the external airflow and the inner gas fluid, located inside the inflation chamber. The aim of the new version of the tire thermal model is a better physical comprehension of all the phenomena concerning the contact with the asphalt and the prediction of the link between the thermal state and the frictional performance, crucial for the definition of an optimal wheel and vehicle setup.

Standardization in Tire Modeling and Tire Testing — TYDEX Workgroup, TIME Project

1999 ◽  
Vol 27 (3) ◽  
pp. 188-202 ◽  
Author(s):  
J. J. M. van Oosten ◽  
H.-J. Unrau ◽  
A. Riedel ◽  
E. Bakker
Keyword(s):  
Measurement Data ◽  
Testing Procedure ◽  
International Colloquium ◽  
Vehicle Modeling ◽  
Testing Procedures ◽  
Research Organizations ◽  
Tire Modeling ◽  
Tire Testing ◽  
To Come ◽  
Tire Models

Abstract As a result of the 1st International Colloquium on Tire Models for Vehicle Dynamics Analysis in 1991, the international TYDEX Workshop working group was established. This workshop concentrated on the standardization of the exchange of tire measurement data and the interface between tire and vehicle models in order to improve the communications between vehicle manufacturers, suppliers, and research organizations. The development and knowledge of tire behavior is of great importance to both the tire and vehicle industries and will be intensified. Therefore the TYDEX Workshop received great interest from all parties to come to some kind of standardization. In the two expert groups, one of which focused on Tire Measurements — Tire Modeling and the other on Tire Modeling — Vehicle Modeling, the TYDEX-Format and the standard tire interface have been developed, which will be explained in this paper. Furthermore, a short overview of the European TIME project aiming at a standard tire testing procedure will be given, which is reliable and consistent with realistic driving conditions. Standard testing procedures are some of the important consequences of the TYDEX Workshop.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

2.2. Working Group 2: Conceptual Definitions of Reference Coordinate Systems for Earth Dynamics

1975 ◽  
Vol 26 ◽  
pp. 21-26
Keyword(s):  
Coordinate System ◽  
Working Group ◽  
General Character ◽  
Coordinate Systems ◽  
Reference Coordinate System ◽  
Group 2 ◽  
Definition Of ◽  
Earth Dynamics

An ideal definition of a reference coordinate system should meet the following general requirements:1. It should be as conceptually simple as possible, so its philosophy is well understood by the users.2. It should imply as few physical assumptions as possible. Wherever they are necessary, such assumptions should be of a very general character and, in particular, they should not be dependent upon astronomical and geophysical detailed theories.3. It should suggest a materialization that is dynamically stable and is accessible to observations with the required accuracy.

Symbiotic Stars at Optical, Infrared and Radio Wavelengths

1979 ◽  
Vol 46 ◽  
pp. 125-149 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Temperature Regime ◽  
Type Star ◽  
Stellar Systems ◽  
Symbiotic Stars ◽  
Lower Excitation ◽  
Definition Of ◽  
Original Type

No paper of this nature should begin without a definition of symbiotic stars. It was Paul Merrill who, borrowing on his botanical background, coined the termsymbioticto describe apparently single stellar systems which combine the TiO absorption of M giants (temperature regime ≲ 3500 K) with He II emission (temperature regime ≳ 100,000 K). He and Milton Humason had in 1932 first drawn attention to three such stars: AX Per, CI Cyg and RW Hya. At the conclusion of the Mount Wilson Ha emission survey nearly a dozen had been identified, and Z And had become their type star. The numbers slowly grew, as much because the definition widened to include lower-excitation specimens as because new examples of the original type were found. In 1970 Wackerling listed 30; this was the last compendium of symbiotic stars published.

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