Virtual Proving Ground Terrain Validation

by Dr. David Lamb, Dr. Alex Reid, Nancy Truong, John Weller(IVSS-2003-MAS-1)

Virtual Proving Ground Terrain Validation

by Dr. David Lamb, Dr. Alex Reid, Nancy Truong, John Weller(IVSS-2003-MAS-1)

3rd Annual Intelligent Vehicle Systems SymposiumNational Defense Industrial Association

10 June 2003

Presented by: Nancy TruongUS Army TACOM-TARDEC

National Automotive Center (NAC)Ground Vehicle Simulation Laboratory (GVSL)

OutlineOutline

• Background Information about Lab

• Visual

• Churchville

• Virtual Profilometer

• Validation Process/Methodology

• NURBS

• Conclusions

• Background Information about Lab

• Visual

• Churchville

• Virtual Profilometer

• Validation Process/Methodology

• NURBS

• Conclusions

RMSRMS

• Capable of reproducing the ride of most ground vehicles • Realistic environment• The Evans and Sutherland ESIG

HD/3000 and Harmony Image Generators.

• Real-time warfighter/hardware-in-the-loopsimulation

• Aberdeen Proving Ground’s (APG) Churchville

Why Do We Need More Resolution?

• To aid in the application of high-fidelity modeling and simulation techniques to the development/testing of new vehicle systems and emerging technologies.

• To include:– motion-based, human- and hardware-in-the-

loop simulations.– high-resolution virtual testing of systems.

Terrain Limitations

• High-resolution dynamic model requires very small terrain resolution

• Higher resolution terrains cannot be rendered in real-time.

3.55

3.6

3.65

x 105

-5.68-5.66

-5.64-5.62

-5.6-5.58

-5.56

x 105

3000

3500

4000

4500• Typical terrain grids come no smaller than 30m x 30m and most areas typically are even lower resolution.

• Use of terrain for primarily off-road simulations

Visual Correlation Questions

• How does the low-resolution IG database correlate to the high-resolution dynamic database?

• Does it need to?

• Why?

Visual Correlation

• Needed to mitigate simulator sickness

• Creates a more realistic virtual environment

• Use Bump-Map Texturing

GVSLGVSL

• Human Factors

• Vehicle performance

• Motion Sickness

• Comparison of head-mounted display (HMD) vs flat panel

• Human Factors

• Vehicle performance

• Motion Sickness

• Comparison of head-mounted display (HMD) vs flat panel

Components of a Real-Time Simulation

Components of a Real-Time Simulation

Mathematical ModelVirtual Environment

Real-Time Computer

Experimental Environment

Churchville Churchville

• Visual- what we see • Terrain- what we feel

• Visual- what we see • Terrain- what we feel

Validate the TerrainValidate the Terrain

• Acquired the data for the virtual terrain,

• Obtained the x & y coordinates

• Input data into the virtual profilometer

• Acquired the data for the virtual terrain,

• Obtained the x & y coordinates

• Input data into the virtual profilometer

Virtual ProfilometerVirtual Profilometer

• Acts the same way a profilometer acts over a read proving ground

• Simulates a trailer

• Reports other terrain properties stored in the database

• Acts the same way a profilometer acts over a read proving ground

• Simulates a trailer

• Reports other terrain properties stored in the database

Equal distance spacingEqual distance spacing

Input-Constant time delta, but at a variable speed

Output- Constant space delta

Arc Length FormulaArc Length Formula

1

0

222t

tdt

t

z

t

y

t

xs

Interpolation of pointsInterpolation of pointsOnce the arc length (distance) down the course to each point in the input series is computed, then interpolate to get points the desired distance apart.

212121 1,1,1 zzyyxx

This is the new point, where the interpolation parameter is

12

1

ss

ss

The desired distance is s, other distances are for the two points

111 ,, zyx 222 ,, zyx

Other FeaturesOther Features

• A rough Power Spectral Density (PSD) of the course

• Various input and output formats are supported

• Options for track offset (left and right) or single track (centerline) available

• A rough Power Spectral Density (PSD) of the course

• Various input and output formats are supported

• Options for track offset (left and right) or single track (centerline) available

Profile DataProfile Data

• MATLAB • Linear interpolation • Two curves start and stop

at the same point • Virtual proving ground

correlated well with large terrain changes

• MATLAB • Linear interpolation • Two curves start and stop

at the same point • Virtual proving ground

correlated well with large terrain changes

MogulsMoguls

• Virtual terrain has sharper hills and valleys •Sampling and construction

RMS ValuesRMS Values

• Removed wavelengths greater than 18m

• Real-terrain is 4.95 cm.

• Virtual terrain is 4.57 cm.

• A difference of 8%.

• Removed wavelengths greater than 18m

• Real-terrain is 4.95 cm.

• Virtual terrain is 4.57 cm.

• A difference of 8%.

PSDPSD

• Virtual terrain is much lower than the real terrain

• Construction of polygons

• Virtual terrain is much lower than the real terrain

• Construction of polygons

NURBSNURBS

• Non-Uniform Rational B-Splines

• Non-Uniform Rational B-Splines

Churchville Without Bump-Mapped Texture

Churchville With Bump-Mapped Texture

ConclusionConclusion

• Need to validate models• Real and virtual terrain

comparisons• NURBS• Work on other APG databases

• Need to validate models• Real and virtual terrain

comparisons• NURBS• Work on other APG databases

QuestionsQuestions

For further information on this presentation, contact:

Dr. David Lamb LambD@tacom.army.mil (586)-574-5209Dr. Alex Reid, ReidA@tacom.army.mil (586)-753-2212Nancy Truong, TruongN@tacom.army.mil (586)-574-8633John Weller, WellerJ@tacom.army.mil (586)-574-8633

Motion Base Technologies TeamTACOM-TARDEC6501 E. Eleven Mile RoadWarren, MI 48397AMSTA-TR-NMS: 157, Bldg 215

For further information on this presentation, contact:

Dr. David Lamb LambD@tacom.army.mil (586)-574-5209Dr. Alex Reid, ReidA@tacom.army.mil (586)-753-2212Nancy Truong, TruongN@tacom.army.mil (586)-574-8633John Weller, WellerJ@tacom.army.mil (586)-574-8633

Motion Base Technologies TeamTACOM-TARDEC6501 E. Eleven Mile RoadWarren, MI 48397AMSTA-TR-NMS: 157, Bldg 215