This paper presents the development of an algorithm to estimate the tractive force of an off-road vehicle with uncertainties in the tire stiffness and in the soil moisture content. The algorithm compares the average ground pressure with the critical ground pressure to decide if the tire can be approximated as a rigid wheel, or if it should be modeled as a flexible wheel, and involves using previously developed vehicle and stochastic soil models, and computing along the way the vehicle sinkage, resistance force, tractive force and drawbar pull. The soil modeling focuses on the efficient treatment of poorly known parameters, such as the soil moisture content, and on the impact of these uncertainties on relationships critical in defining the mobility of an off-road vehicle, such as the pressure-sinkage and the shear stress-shear displacement relations. The uncertainties in the tire stiffness and in the soil properties are propagated through the model, and the uncertainty in the output of the vehicle model is analyzed. Such simulations can provide the basis for the study of ride performance, handling, and mobility of the vehicle in off-road conditions. The vehicle model used has seven degrees of freedom. Each of the four suspension systems comprises of a nonlinear spring and a linear viscous damper. The analysis of the dynamic response of the vehicle is performed for two scenarios: a light cargo, and a heavy cargo.

1.
Sandu, A., Sandu, C., and Ahmadian, M. - “Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and Computational Aspects”, Multibody System Dynamics, accepted Oct. 2005, in print.
2.
Sandu, C., Sandu, A., and Ahmadian, M. - “Modeling Multibody Dynamic Systems With Uncertainties. Part II: Numerical Applications”, Multibody System Dynamics, accepted Oct. 2005, in print.
3.
Sandu, C., Sandu, A., Chan, B.J., and Ahmadian, M. - “Treating Uncertainties in Multibody Dynamic Systems using a Polynomial Chaos Spectral Decomposition”, Proc. of the ASME IMECE 2004, 6th Annual Symposium on “Advanced Vehicle Technology”, Paper number IMECE2004-60482, Nov. 14–19, 2004 Anaheim, CA.
4.
Sandu, C., Sandu, A., Chan, B.J., and Ahmadian, M. - “Treatment of Constrained Multibody Dynamic Systems with Uncertainties”, Proc. of the SAE Congress 2005, Paper number 2005-01-0936, April 11–14, 2005, Detroit, MI.
5.
Li, L., Sandu, C., Sandu, A. - “Modeling and Simulation of a Full Vehicle with Parametric and External Uncertainties”, Proc. of the 2005 ASME Int. Mechanical Engineering Congress and Exposition, 7th VDC Annual Symposium on “Advanced Vehicle Technologies”, Session 4: Advances in Vehicle Systems Modeling and Simulation, Paper number IMECE2005-82101, Nov. 6–11, 2005, Orlando, FL.
6.
Sandu, C., Sandu, A., Li, L. - “Stochastic Modeling of Terrain Profiles and Soil Parameters”, SAE 2005 Transactions Journal of Commercial Vehicles, 2005-01-3559.
7.
Wong, J. Y. - “Theory of Ground Vehicles”, John Wiley & Sons, Inc., Third Edition, 2001.
8.
Muro, T. and O’Brien, J. - “Terramechanics. Land Locomotion Mechanics”, A.A. Balkema Publishers, 2004.
9.
Shibly
H.
,
Iagnemma
K.
,
Dubowsky
S.
- “
An equivalent soil mechanics formulation for rigid heels in deformable terrain, with application to planetary exploration rovers
”,
Journal of Terramecanics
, Vol.
42
,
1
13
,
2005
.
10.
Rosca R., Rakosi E., Manolache GH., Cojocariu P. - “Wheel Traction Prediction on Agricultural Soil”, A 30-a conferinta a Academiei Tehnice Militare, 133–139, Nov. 6–7, 2003, Bucuresti,
11.
Plackett
C. W.
- “
A Preview of Force Prediction Methods for Off-road Wheels
”,
Journal of Agricultural Engineering Research
, Vol.
31
, No.
1
,
1
29
,
1985
.
12.
Okello
J. A.
. - “
A Review of Soil Strength Measurement Techniques for Prediction of Terrain Vehicle Performance
”,
Journal of Agricultural Engineering Research
, Vol.
50
, No.
2
,
129
155
,
1991
.
13.
Okello
J. A.
. - “
Prediction of the Force Distribution Between the Soil and Pneumatic Wheel
”,
Journal of Agricultural Engineering Research
, Vol.
51
, No.
4
,
249
262
,
1992
.
14.
Reina, Guilio, Ojeda, Lauro, Milella, Annalisa, Borenstein, Johann. “Measurement for Wheel Slippage and Sinkage Detection in Rough-Terrain Mobile Robots”, Proceedings of IMECE2005, IMECE2005-79711, Nov 5–11, 2005, Orlando, Florida.
15.
Walczykova, Maria., Walczyk, Jozef., Kormanek, Mariusz., “Determination of Forest Soil Traction Parameters”, Electronic Journal of Polish Agricultural Universities, Forestry, Vol 5, Issue 2.
16.
Iagnemma, K., and Dubowsky, S., “Terrain Estimation for High-Speed Rough-Terrain Autonomous Vehicle Navigation,” Proceedings of the SPIE Conference on Unmanned Ground Vehicle Technology IV, 2002
17.
Amy C. Larson. Richard M. Voyles Guleser K. Demir. Terrain classification through weakly-structured vehicle/terrain interaction. Robotics and Automation, 2004. Proceedings. ICRA ’04. 2004 IEEE International Conference on. page(s): 218–224 Vol. 1
18.
Rober E. Karlsen, James L. Overholt. Run-Time Assessment of Vehicle-Terrain Interaction. 24th Army Science Conference Proceedings. Nov.29–Dec.2, 2004.
19.
Karl Iagnemma, Dariusz Golda, Matthew Spenko, Steven Dubowsky. Experimental Study of High-Speed Rough-Terrain Mobile Robot Models for Reactive Behaviors.
20.
Nunez, P., Jones, R., and Shoop, S. - “High-Fidelity Ground Platform and Terrain Mechanics Modeling for Military Applications Involving Vehicle Dynamics and Mobility Analysis”, 24th Army Science Conference Proceedings, Session C, CP-06, Nov. 29–Dec. 2, 2004.
21.
Yoon
Sugjoon.
, “
A Study on Terrain-Surface Modeling and Searching Algorithms for Real-Time Simulation of Off-Road Vehicles
”,
Vehicle System Dynamics
, Vol.
39
, No.
5
,
2003
,
353
363
.
22.
Ferris
J. B.
, “
Characterising Road Profiles as Markov Chains
”,
Int. J. Vehicle Design
, Vol.
36
, Nos.
2/3
,
2004
,
103
115
.
This content is only available via PDF.
You do not currently have access to this content.