Off-Road Vehicle Dynamics Mobility Simulation With a Compaction Based Deformable Terrain Model

2013 ◽  
Author(s):  
Justin Madsen ◽  
Andrew Seidl ◽  
Dan Negrut
Keyword(s):  
Vehicle Dynamics ◽  
Transfer Functions ◽  
Soil Mechanics ◽  
Three Dimensional ◽  
Interaction Model ◽  
Simulation Software ◽  
Repeated Loading ◽  
Model Parameters ◽  
Vehicle Simulation ◽  
Terrain Model

This paper discusses the terramechanics models developed to incorporate a physics-based, three dimensional deformable terrain database model with vehicle dynamics mobility simulation software. The vehicle model is contained in Chrono, a research-grade C++ based Application Programming Interface (API) that enables accurate multibody simulations. The terrain database is also contained in a C++ based API, and includes a general tire-terrain interaction model which is modular to allow for any tire model that supports the Standard Tire Interface (STI) to operate on the terrain. Furthermore, the ability to handle arbitrary, three dimensional traction element geometry allows for tracked vehicles (or vehicle hulls) to also interact with the deformable terrain. The governing equations of the terrain are based on a soil compaction model that includes both the propagation of subsoil stresses due to vehicular loads, and the resulting visco-elastic-plastic stress/strain on the affected soil volume. Non-flat, non-homogenous and non-uniform soil densities, rutting, repeated loading and strain hardening effects are all captured in the vehicle mobility response as a result of the general 3-D tire/terrain model developed. Pedo-transfer functions allow for the calculation of the soil mechanics model parameters from existing soil measurements. This terrain model runs at near real-time speed, due to parallel CPU and GPU implementation. Results that exercise the force models developed with the 3-D tire geometry are presented and discussed for a kinematically driven tire and a full vehicle simulation.

A Physics-Based Terrain Model for Off-Road Vehicle Simulations

2012 ◽  
Author(s):  
Justin Madsen ◽  
Paul Ayers ◽  
Alexander Reid ◽  
Andrew Seidl ◽  
George Bozdech ◽  
...  
Keyword(s):  
Soil Compaction ◽  
Three Dimensional ◽  
Interaction Model ◽  
Simulation Software ◽  
Governing Equations ◽  
Terrain Model ◽  
Vehicle Mobility ◽  
Terrain Representation ◽  
Tire Forces ◽  
Power And Energy

We present the development of a three-dimensional Vehicle/Tire/Terrain Interaction Model (VTTIM) consisting of a general 3D tire-terrain traction model which operates on a novel deformable terrain representation that utilizes a soil compaction model. Rather than utilizing popular empirical terramechanics models that only consider the pressure/sinkage directly under the tire, the governing equations of the terrain are based on i) the propagation of subsoil stresses due to vehicular loads, and ii) the resulting stress/strain which is based on a visco-elastic-plastic soil model developed by Ayers and Bozdech. The implementation of the terrain model is modularized in the form of an API, as the vehicle and tire are assumed to be contained in commercial simulation software as to focus on the implementation of the deformable terrain model. A number of test simulations are run using a rigid tire with and without grousers to show the capability of the VTTIM to predict tire forces for use in vehicle mobility and traction performance simulations. Power and energy required to deform the terrain will also be presented with the simulation results, which allows the prediction of the extra power required by a vehicle traveling on off-road, deformable soil.

Estimating Pacejka (PAC2002) Tire Coefficients for Pneumatic Tires on Soft Soils With Application to BAJA SAE Vehicles

2019 ◽  
Author(s):  
Amanda Saunders ◽  
Darris White ◽  
Marc Compere
Keyword(s):  
Vehicle Dynamics ◽  
Integration Method ◽  
Simulation Software ◽  
Dynamics Simulation ◽  
Road Vehicles ◽  
Traction Forces ◽  
Soft Soils ◽  
Vehicle Performance ◽  
Vehicle Simulation ◽  
Stress Integration

Abstract BAJA SAE is an engineering competition that challenges teams to design single-seat all-terrain vehicles that participate in a vast number of events, predominately on soft soils. Efficient performance in the events depends on the traction forces, which are dependent on the mechanical properties of the soil. To accurately model vehicle performance for each event, a model of the tire traction performance is required, and the tire model must be incorporated with a vehicle dynamics simulation. The traction forces at the soil-tire interface can be estimated using the Bekker-Wong stress integration method. However, commercially available vehicle dynamics simulation software, with a focus on on-road vehicles, does not utilize Bekker-Wong parameters. The Pacejka Magic Tire (MT) Formula is a common method for characterizing tire behavior for on-road vehicles. The parameters for the Pacejka MT Formula are usually produced by curve fitting measured tire data. The lack of available measured off-road tire data, as well as the additional variables for off-road tire performance (e.g. soil mechanics), make it difficult for BAJA SAE teams to simulate vehicle performance using commercial vehicle simulation tools. This paper discusses the process and results for estimating traction performance using the Bekker-Wong stress integration method for soft soils and then deriving the Pacejka coefficients based on the Bekker-Wong method. The process will enable teams to use the Pacejka Magic Tire Formula coefficients for simulating vehicle performance for BAJA SAE events, such as the hill climb, (off-road) land maneuverability, tractor pull, etc.

Development of an Intermediate Degree of Freedom Vehicle Dynamics Model for Optimal Design Studies

2000 ◽  
Author(s):  
Erik M. Lowndes ◽  
J. W. David
Keyword(s):  
Optimal Design ◽  
Vehicle Dynamics ◽  
Control Algorithm ◽  
Three Dimensional ◽  
Dynamics Model ◽  
Design Studies ◽  
Vehicle Simulation ◽  
Race Car ◽  
Sufficient Detail ◽  
Intermediate Degree

Abstract Today’s race teams spend a significant amount of time and money performing on-track testing of their vehicles in order to determine the best possible suspension configuration for a particular racing venue. The use of computer simulation coupled with optimal design techniques presents the opportunity to significantly reduce the amount of on-track testing required. Many of the existing vehicle simulation codes are not suitable for application to the optimal design problem, either because they incorporate too much detail and run too slowly, or because they lack sufficient detail. A new model that bridges the gap between these two existing classes of models and is suitable for performing optimal design has been developed. The vehicle model is fully three dimensional and nonlinear. A driver control algorithm was developed that is capable of driving the car near it’s handling limits. An attempt was made to optimize the suspension setup for the NCSU Legends race car.

A Nonlinear Three-Dimensional Coupled Fluid-Sediment Interaction Model for Large Seabed Deformation

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Tomoaki Nakamura ◽  
Solomon C. Yim
Keyword(s):  
Sediment Transport ◽  
Three Dimensional ◽  
Interaction Model ◽  
Navier Stokes ◽  
Coupling Scheme ◽  
Model Parameters ◽  
Interface Tracking ◽  
Beach Profile ◽  
Time Step ◽  
Profile Change

A nonlinear three-dimensional two-way coupled fluid-sediment interaction model is developed in this study. The model is composed of a generalized Navier–Stokes solver (GNS) with a volume of fluid module for air-water interface tracking and a sediment transport module (STM) for fluid-sediment interface tracking. The GNS model is based on the finite difference method with a turbulent stress model of large-eddy simulation to compute incompressible viscous multiphase flows. The STM is used to compute nonlinear sediment bed profile change due to bed-load sediment transport. A two-way coupling scheme connecting GNS with STM is implemented at each time step to ensure the fluid-sediment interaction. For validation, the fluid-sediment interaction model is applied to predict cross-shore profile change of a sloping beach due to breaking solitary waves, and the resulting predictions are examined and compared with the measured data from a set of hydraulic tests. It is found that the fluid-sediment interaction model predicts reasonably well the sediment transport and the resulting beach profile change. The sensitivity of model parameters involving the sediment transport to the beach profile change is analyzed. Finally, the fluid-sediment interaction model is applied to predict local scour in front of a quay wall due to a jet flow to demonstrate its applicability to general three-dimensional problems.

A Novel Wheel-Soil Interaction Model for Off-Road Vehicle Dynamics Simulation

2007 ◽  
Author(s):  
Brendan J. Chan ◽  
Corina Sandu
Keyword(s):  
Vehicle Dynamics ◽  
Three Dimensional ◽  
Interaction Model ◽  
Equilibrium Analysis ◽  
Dynamics Simulation ◽  
Tire Model ◽  
Wheel Load ◽  
Surface Shear ◽  
Modeling Methodology ◽  
Semi Empirical

This work establishes a semi-empirical wheel-soil interaction model, developed in the framework of plasticity theory and equilibrium analysis, to be used in vehicle dynamics simulations. Vehicle-terrain interaction is a complex phenomena governed by soil mechanical behavior and tire deformation. The application of soil load bearing capacity theory is used in this study to determine the tangential and radial stresses on the soil-wheel interface. Using semi-empirical data, the tire deformation geometry is determined to establish the drawbar pull, tractive force, and wheel load. To illustrate the theory developed, two important case studies are presented: a rigid wheel and a flexible tire on deformable terrain; the differences between the two implementations are discussed. The outcome of this work shows promising results which indicate that the modeling methodology presented could form the basis of a three-dimensional off-road tire model. In an off-road three-dimensional tire model, the traction behavior should include shear forces arising from the surface shear with the soil as well as the bulldozing effect during turning maneuvers.

Establishing design guidelines for compound horizontal curves on three-dimensional alignments

2005 ◽  
Vol 32 (4) ◽  
pp. 615-626 ◽  
Author(s):  
Said Easa ◽  
Essam Dabbour
Keyword(s):  
Three Dimensional ◽  
Design Guidelines ◽  
Simulation Software ◽  
Lateral Acceleration ◽  
Vertical Alignment ◽  
Vehicle Simulation ◽  
Minimum Radius ◽  
Horizontal Curves ◽  
Flat Terrain ◽  
Current Design

In current design guides, the minimum radii of compound horizontal curves are based on the design requirements of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two-dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments examined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius requirements were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment.Key words: highway geometric design, compound horizontal alignments, side friction, vehicle simulation, 3-D alignments.

scholarly journals Interactive, visual simulation of a spatio-temporal model of gas exchange in the human alveolus

2021 ◽  
Author(s):  
Kerstin Schmid ◽  
Andreas Knote ◽  
Alexander Mueck ◽  
Keram Pfeiffer ◽  
Sebastian von Mammen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Gas Exchange ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Simulation Software ◽  
Visual Simulation ◽  
Model Parameters ◽  
Interactive Simulation ◽  
Temporal Model ◽  
Spatio Temporal

In interdisciplinary fields such as systems biology, close collaboration between experimentalists and theorists is crucial for the success of a project. Theoretical modeling in physiology usually describes complex systems with many interdependencies. On one hand, these models have to be grounded on experimental data. On the other hand, experimenters must be able to penetrate the model in its dependencies in order to correctly interpret the results in the physiological context. When theorists and experimenters collaborate, communicating results and ideas is sometimes challenging. We promote interactive, visual simulations as an engaging way to communicate theoretical models in physiology and to thereby advance our understanding of the process of interest. We defined a new spatio-temporal model for gas exchange in the human alveolus and implemented it in an interactive simulation software named Alvin. In Alvin, the course of the simulation can be traced in a three-dimensional rendering of an alveolus and dynamic plots. The user can interact by configuring essential model parameters. Alvin allows to run and compare multiple simulation instances simultaneously. The mathematical model was developed with the aim of visualization and the simulation software was engineered based on a requirements analysis. Our work resulted in an integrative gas exchange model and an interactive application that exceed the current standards. We exemplified the use of Alvin for research by identifying unknown dependencies in published experimental data. Employing a detailed questionnaire, we showed the benefits of Alvin for education. We postulate that interactive, visual simulation of theoretical models, as we have implemented with Alvin on respiratory processes in the alveolus, can be of great help for communication between specialists and thereby advancing research.

Real-Time Vehicle Dynamics Parameter Estimation

2005 ◽  
Author(s):  
Kwang-Keun Shin
Keyword(s):  
Parameter Estimation ◽  
Control Systems ◽  
Real Time ◽  
Vehicle Dynamics ◽  
Estimation Method ◽  
Vehicle Control ◽  
Simulation Software ◽  
Tire Pressure ◽  
Vehicle Simulation ◽  
The Stability

Vehicle dynamics parameters such as understeer coefficient are very important factors to determine the stability and dynamic handling behavior of a vehicle. These parameters vary during the lifetime of a vehicle according to different loading, tire pressure/wear or vehicle-to-vehicle variations of suspension characteristics, etc. The parameter deviations from nominal values may cause performance degradation of chassis/vehicle control systems, which is often designed based on the nominal values. Therefore, if the vehicle dynamics parameters can be estimated and monitored in real-time, the performance of chassis/vehicle control systems could be further enhanced. This paper presents a real-time vehicle dynamics parameter estimation method that estimates vehicle understeer coefficient and front/rear cornering compliances. The algorithm is implemented using Simulink, and analyzed, and validated using VehSim, which is a PC windows-based vehicle simulation software for vehicle dynamics controls and integration. The simulation results show that the developed algorithm is well capable of estimating vehicle dynamics parameters of VehSim, and, therefore, is highly feasible for in-vehicle applications.

Analysis of Tire Models for Rolling on a Deformable Substrate

2002 ◽  
Vol 30 (3) ◽  
pp. 180-197 ◽  
Author(s):  
S. Shoop ◽  
I. Darnell ◽  
K. Kestler
Keyword(s):  
Finite Element ◽  
Vehicle Dynamics ◽  
Three Dimensional ◽  
Element Model ◽  
Tire Model ◽  
Terrain Model ◽  
Vehicle Mobility ◽  
Conventional Models ◽  
Dynamics Simulations ◽  
Tire Models

Abstract The objective of this research is to produce a finite element model of tire-terrain interaction that can be used to explore the effects of tire and terrain variables on vehicle mobility and terrain deformation. Such a model would need to account for the deformable nature of both the tire and the terrain and be fully three-dimensional. Thus, it is important that the tire model be very efficient at rolling yet retain realistic surface contact and deformation related to contact. A promising methodology was developed by Darnell for efficiently modeling a tire for vehicle dynamics simulations. The performance of the Darnell model was examined with respect to measured tire deformation as well as to conventional models of the same tire. The Darnell tire model was then rolled across a soil simulating the sand used in off-road vehicle experiments. The combined tire-terrain model presented is fully operational, but optimization and validation are in progress.

An Integrated Environment for Vehicle Dynamics Controls and Integration

2000 ◽  
Author(s):  
Weiwen Deng ◽  
Yong Lee ◽  
Robert Nisonger ◽  
Yuen-kwok Chin
Keyword(s):  
Visual Processing ◽  
Vehicle Dynamics ◽  
Algorithm Design ◽  
Simulation Software ◽  
Development Environment ◽  
Vehicle Simulation ◽  
On Line ◽  
Simulation Results ◽  
User Friendly ◽  
And Control

Abstract This paper provides an overview of VehSim, a PC Windows-based vehicle simulation software for vehicle dynamics, controls and integration. The function and features of VehSim are discussed in general. With its high fidelity, flexibility, portability and user-friendly interfaces, VehSim provides an integrated development environment for engineers to conduct vehicle, especially chassis/driveline modeling, simulation and control algorithm design and to build quick software prototypes to accelerate chassis/driveline controls and integration development. VehSim’s structure, which includes file system, database structure and user graphic interfaces are described. Through its modularized and hierarchical structure, VehSim features great flexibility for engineers to customize their own project needs by developing their own control algorithms or incorporating supplier provided subsystem models and control modules into vehicle dynamics. With the compatibility of VehSim to real-time environment, engineers are able to perform both quick off-line simulation and on-line in-vehicle validation for algorithm development. VehSim also provides built-in user-friendly model preprocessors and postprocessors for engineers to easily build vehicle and/or subsystem models, adjust numerical computation parameters and process the simulation results on line. A 3D solid model based motion animator is also integrated in VehSim for on-line visual processing of simulation results.

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