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2007-11-0101 Author(s) Info Title: “High-Fidelity Ground Platform and Terrain Mechanics Modeling for Military Applications Involving Vehicle Dynamics and Mobility Analysis” Author(s): Alexander A. Reid, Sally Shoop, Randy Jones and Patrick Nunez Abstract: The High-Fidelity Ground Platform and Terrain Mechanics Modeling (HGTM) project was a multi-laboratory program, concluding in 2006. The program objectives were to develop methods to facilitate the creation and application of high fidelity, real-time, ground platform mobility and terrain models. The models are applicable to warfighter in the loop virtual experiments investigating methods of mitigating the effects of motion on soldier performance, for the development and evaluation of conceptual manned and unmanned ground platform dynamic performance and mobility, and as a component of embedded simulation and training systems. The HGTM program is a collaboration of several of the major US vehicle mobility research organizations including two U.S. Army Corps of Engineers ERDC (Engineering, Research and Development Center) laboratories and two U.S. Army RDECOM (Research Development and Engineering Command) ARDEC (Army Research, Development and Engineering Center) laboratories; CRREL (Cold Regions Research and Engineering Laboratory), GSL (Geotechnical and Structures Laboratory), ARL (Army Research Laboratory), and TARDEC (Tank and Automotive Research Development & Engineering Center), with TARDEC as the lead laboratory. The purpose of the HGTM was to develop real-time ground platform mobility and terrain modeling and simulation technologies and to employ these technologies towards human performance experiments, and towards accurate and realistic simulation of the Vehicle-Terrain Interface (VTI). The four year program started in October 2002. The first year concentrated on setting up the architecture for real-time vehicle simulations which realistically include the impact of off-road terrain. The second year consisted of several experiments for human-in-the-loop applications, and the final two years consisted of the full implementation, verification and validation of the Vehicle Terrain Interface (VTI). This paper provides an overview of the HGTM vehicle and terrain Modeling and Simulation technology development effort and a description of the application of the products. Title: “A Vehicle Terrain Interface” Author(s): Randolph A. Jones, George B. McKinley, Paul W. Richmond, et. al. Abstract: Researchers at the U.S. Army Engineer Research and Development Center (ERDC) and the U.S. Army Tank Automotive Research Development and Engineering Center (TARDEC) working in the field of vehicle mobility, have developed methods to predict the real-time physical interactions of vehicles with terrain surfaces during vehicle dynamic simulations. The terrain mechanics methods used for this research were developed at the ERDC to predict the physical interactions of vehicles and terrain surfaces under all seasons. The Vehicle Dynamics and Mobility Server (VDMS), being developed by TARDEC, is a real-time vehicle dynamics simulator that is using these terrain mechanic methods. The terrain mechanics were developed from historical research that quantified and related a set of fundamental vehicle traction element performances to easily obtainable terrain properties. This empirical and lumped parameter approach has provided relevant and verifiable results, but due to its nature, is difficult to extrapolate and manipulate mathematically. Nevertheless, the ease of obtaining suitable terrain properties, its historical success in vehicle performance predictions, and its maturity and broad validation database have made it an attractive choice for implementation in a real time vehicle simulator. This paper describes the algorithms selected for estimating longitudinal and lateral force coefficients and sinkage for soils and the underlying assumptions. Title: “Verification and Validation of a Winter Driving Simulator” Author(s): Michael Parker, Sally Shoop, Barry Coutermarsh, et. al. Abstract: A full vehicle dynamics simulator was constructed in SimCreator® for the CRREL Instrumented Vehicle (CIV) and was used to investigate and validate the newly developed Vehicle Terrain Interaction (VTI) code. The VTI code replaces the existing tire component of the CIV dynamics model and allows the vehicle to report back realistic values while driving on various types of terrain surfaces such as mud, snow, ice, and pavement. The validation effort within this paper is focused on the winter (snow and ice) parts of the VTI code. The outputs from the ERDC and Simulator VTI codes were validated through field experiments and against the NATO Reference Mobility Model (NRMM). The VTI code can be used with different vehicle models, providing the Army with a valuable asset that will allow simulation of existing or conceptual, manned or autonomous ground vehicle performance for acquisition, planning or training. This information, along with some basic terrain information, will allow troops to plan the fastest and most effective way of getting to a desired location, while minimizing the possibility of being delayed because of the terrain conditions. Title: “Cross-Country Mobility on Various Snow Conditions for Validation of a Virtual Terrain” Author(s): Rosa T. Affleck, Rae A. Melloh and Sally A. Shoop Abstract: This work is a part of validating the virtual test site of an Army firing range in northern Vermont. The objective was to realistically simulate on- and off-road vehicle performance in all weather conditions for training and vehicle design for the US Army. The virtual terrain incorporated with terramechanics properties was developed to mimic the terrain at Ethan Allen Firing Range (EAFR). Instrumented vehicles were used at the test site to perform maneuvers to validate mathematics models describing vehicle behavior in all-season conditions, including snow, ice, and frozen and thawing ground. The terramechanics (terrain codes) were derived from spatial information and composed of spatially distributed soil, drainage, and vegetation properties. A more sophisticated method of incorporating the spatially distributed snow properties into the terramechanics was based on elevation, slope, and aspect. This report examines the cross-country vehicle performance using the NATO Reference Mobility Model (NRMM) to validate the Vehicle–Terrain–Interface terramechanics code using the new algorithms for realistic spatial distribution of snow properties. The percentage of Nogo areas for uniform snow is lower than the distributed snow by 4% for the CIV, 8% for the HMMWV, and 5% for the Stryker. For both light vehicles, approximately 12% of the Nogo areas are due to slopes of equal to and greater than 29%. Title: “Tire Slip-Angle Force Measurements on Winter Surfaces” Author(s): Barry A. Coutermarsh and Sally A. Shoop Abstract: Tire Lateral force data on winter surfaces can not be obtained with the traditional laboratory test technique of an instrumented tire on a moving belt surface. Furthermore, changing snow and ice conditions can drastically change the tire/surface interaction. In this study the Cold Regions Research and Engineering Laboratory’s (CRREL’s) Instrumented Vehicle (CIV) was used in a unique configuration to measure tire lateral force versus slip-angle data on ice and snow at various temperatures, moisture contents, depths and densities. The vehicle is instrumented to record longitudinal, lateral and vertical force at the tire contact patch of each wheel as well as vehicle speed, tire speed and front tire slip angle. The tests were conducted at the Keweenaw Research Center (KRC) in northern Michigan in February, 2005 and March 2006. Tests were conducted on ice, packed snow from 0.50 g/cc to 0.58 g/cc, remixed snow depths of 2.5 to 20.3 centimeters at 0.43 g/cc to 0.48 g/cc and freshly fallen snow with depths of 0.5 to 17 centimeters at 0.07 g/cc to 0.23 g/cc. Surface air temperatures during testing ranged from -14° to 1.6° C. The data collected show that peak lateral force and the shape of the lateral force versus slip angle curve are related to snow properties and depths. Title: “Over-Snow Rolling Resistance of Wheeled Vehicles” Author(s): J.H. Lever and S.A. Shoop Abstract: Rolling resistance of wheeled vehicles over snow includes the work required to compact the snow to support vehicle weight. This extra resistance can be critical for lightweight robots that carry limited onboard energy. Most manned vehicles can only drive through shallow snow, where the wheels compact the snow onto a hard substrate. CRREL has compiled a large database of the rolling resistance of manned vehicles on shallow snow. However, lightweight all-terrain vehicles and robots can support themselves on snow without completely compressing it. This is intermediate between the cases of shallow and deep snow, the latter being the case when the compaction effect does not reach a hard substrate. We present a modified version of Bekker mobility theory for wheeled vehicles that accounts for the observed asymptotic rise in pressure as snow is compacted towards a hard substrate. This formulation covers the range of wheel compaction from shallow to deep snow, or large to small sinkage relative to snow depth. It requires only two snow parameters: the sinkage asymptote and the linear slope of the pressure-sinkage curve for small indentation. Considering its simplicity, the predicted rolling resistance over snow agrees remarkable well for vehicles ranging from a 2,500-kg four-wheel drive truck driving over temperate snow to a 61-kg robot driving over polar snow in Greenland. It offers simple guidance to estimate the over-snow resistance of wheeled vehicles across the size range from manned vehicles to lightweight robots. Title: “Characterization of Snow Cover for Vehicle Mobility Using Ground Penetrating Radar – Experiments and Modeling” Author(s): Jonah Lee and Wei Wang Abstract: It is highly desirable to obtain information about the geometry and material properties of terrains over which vehicles will traverse, preferably in a non-contact manner. The Ground Penetrating Radar (GPR) has emerged as a leading remote-sensing method to probe subsurface properties of terrains. However, most of the studies conducted so far using GPR on snow have not focused on determining the strength or density of snow from radar signal. The goal of this paper is then to correlate the strength of snow with its dielectric constant using GPR as a function of snow density. We present preliminary results where the dielectric constant and depth of layered dry snow are obtained using GPR, and the hardness of snow is obtained using rammsonde, as a function of snow density. We used single- and multiple-layered snow of which density is varied in the range of 150 to 450 3meterkg in its natural state, as well as sieved snow for the experiments. To better interpret the GPR signal, we also conducted modeling and simulation of GPR operating on layered dry snow. Given depth and dielectric constant of snow, one can simulate the time-history of GPR signal in a layered medium which is called forward modeling. On the other hand, given the time-varying GPR signal, the determination of depth and dielectric constant is called backward modeling. For forward modeling, we used the Finite Difference Time Domain program GPRMAX as well as the transmission line theory (TLT). For backward modeling, we used the layer striping method using the field data as well as the output from forward modeling. Comparisons of results from experiments and models indicate that GPR has a strong potential for the characterization of snow cover for vehicle mobility. Title: “Development of Tire-on-Stochastic Snow Models Using a Polynomial Chaos Approach” Author(s): Lin Li, Corina Sandu, Jonah Lee and Qing Liu Abstract: The analysis of the interaction between a pneumatic tire and unprepared terrain is always a challenging endeavor, but the tire-snow interaction presents very specific aspects. According to recent studies, the snow can be classified in eight groups, based on temperature, precipitation, wind speed, and geographic location. Regardless of the snow group, the tire-snow interaction is mainly influenced by two important snow parameters: the snow depth and snow density, which are very difficult to measure at all locations of interest and hard to predict using deterministic mathematical models. This study presents an effort to construct a stochastic snow model using a polynomial chaos approach in order, to account for the variability of the snow depth. Moreover, the stochastic snow models are developed in conjunction with different types of off-road tire-snow interaction models to predict the system response under the uncertainties considered. The method used in this study to treat the uncertainties in the system is based on prior work of the co-authors at Virginia Tech, employing the polynomial chaos expansion approach. The tire-snow model presented in this study is based on prior work of the co-authors at University of Alaska on tire-snow interaction using an upper bound indentation model, an FEA model, a predictive semi-analytical model, and field test data. We expanded the deterministic pressure-stress tire-snow model, which assimilates the snow with a pressure-sensitive Drucker-Prager material, to a stochastic semi-analytical snow model, and analyzed it under combined slip conditions. An on-road semi-analytical tire model has also been expanded for use in off-road conditions. The tire sinkage in the snow, tire deformation and relaxation length, pressure-sinkage relation, shear stress-shear displacement relation, and forces in the contact patch are predicted while accounting for the uncertain snow depth. The tractive force, drawbar pull, and resistance force in the longitudinal and lateral directions are also calculated. The stochastic tire-snow interaction model can be further extended by incorporating other uncertain parameters of interest, such as uncertain snow density and those associated with the tire. The polynomial chaos approach employed to quantify and propagate the uncertainties in this study has the advantage of accommodating large uncertainties while being very efficient computationally. The model can be used to efficiently predict vehicle mobility and performance of wheeled vehicles on snow. Title: “Semi – Analytical Semi Numerical Track Soil Model” Author(s): Mustafa Alsaleh Abstract: The design of tracked vehicles using numerical models has developed dramatically during the last four decades. Given the limitations in the computational resources and the experimental data three decades ago, Caterpillar Inc. research started modeling the tracks and tracked vehicles using simple 2D analytical models. Those 2D models evolved over the last three years to a full 3D machine models that can handle all machine dynamics including the track soil interaction. This study intends to discuss issues related to the design of track system; track components, tractive performance and the evaluation of track soil models from very simple analytical 2D models to fully dynamic 3D model. A semi analytical, semi numerical track soil model that has been developed borrowing tools from fundamentals in soil mechanics and the theory of plasticity; the model is proposed and briefly discussed. The model has been implemented in an in-house developed multibody dynamics code. Model predictions obtained for different tracked vehicles on different soil properties and irregular ground surfaces show that the model is capturing the dynamics of the track – soil interaction. Title: “Simulation Model of Rotary Tillage for Designing Rotary Blade - Deformation and Stress Analysis of Rotary Blade” Author(s): Ayaka Sato, Takashi Kataoka, Hiroshi Okamoto and Shun-ichi Hata Abstract: The performances of the rotary tillage is characterized by the power requirement of the rotary tiller and the final condition of the tilled soil in terms of the degree of soil pulverization, the clod size distribution and soil moisture within the tilled soil layer (the uniformity of mixing). The key factor affecting the performance of the rotary tiller is the blade configuration. The blade of the rotary tiller has been designed depending on the engineers' experience and intuition. This means that a lot of time and money has been consumed with minor significant output. A simulation model to facilitate the evaluation of the rotary tillage performance would be more effective to design and develop the rotary blade and the tiller. The objective of this study is to construct and develop a simulation model to evaluate the performance of the rotary tillage. This paper analyzed the deformation and stress of the rotary blade under different force conditions using 3-D CAD software. The deformation of the blade during the soil cutting is an important index related to the direction of the cut soil throw. Furthermore, knowing the blade status during the soil cutting process is helpful for developing the simulation model of the rotary tillage. The configuration of the tested blade measured using a laser distance sensor, and the 3-D drawing was produced by the 3-D CAD software (Solid Works). The stress and deformation of the blade were analyzed by 3-D statistical analysis software (COSMOS Works), under the different magnitude of forces and their directions relative to the blade. The magnitude of the force applied to the blade was estimated from the maximum torque of the rotary shaft. As a result of the analysis, the blade has a maximum deformation of about 3.8mm at the tip. The relationship between the deformation of the blade during soil cutting and the tilled soil throwing will be examined in the future. Title: “Parameter Estimation Method Using an Extended Kalman Filter” Author(s): Emmanuel Blanchard, Adrian Sandu and Corina Sandu Abstract: Fast parameter estimation is a non-trivial task, and it is critical when the system parameters evolve with time, as demanded in real-time control applications. In this study, a new computational approach for parameter identification is proposed based on the application of polynomial chaos theory. The polynomial chaos approach has been shown to be considerably more efficient than Monte Carlo in the simulation of systems with a small number of uncertain parameters. In the framework of this new approach, a (suboptimal) Extended Kalman Filter (EKF) is used to recalculate the polynomial chaos expansions for the uncertain states and the uncertain parameters. As a case study, the proposed parameter estimation method is applied to a four degree-of-freedom roll plane model of a vehicle for which the vertical stiffnesses of the tires are estimated from periodic observations of the displacements and velocities across the suspensions. The results obtained with this approach are close to the actual values of the parameters. In addition, the EKF approach gives more information about the parameters of interest than a simple estimated value: the estimation comes in the form of a probability density function. The approach presented in this paper has shown great promise for an improvement in the computational efficiency of current parameter estimation methods. Possible applications of this theory to the field of off-road vehicle simulations include the estimation of various vehicle parameters of interest, as well as the estimation of parameters related to the tire-terrain contact. Title: “A Holistic Simulation Approach to Assess Off-Road Mobility Performance” Author(s): Guido Korlath Abstract: According to the general tendency, modern vehicles – and especially off-road vehicles – are equipped with all technical features available on the market. It is undoubted, that all these features relieve the operator. But nevertheless the operator is still a main factor when the overall performance of a mobility system is considered. Therefore, individual, operator incorporating, situation dependent analysis is much in demand. The presented paper shows a simulation approach to analyze the influence of subjective operator decisions on mobility behavior of off-road vehicles. Exemplary results show, what could be expected, if it comes to very individual situation-dependent decisions – especially in off-road terrain a key factor for the overall mobility performance – concerning braking, accelerating, shifting, engine load, etc. Taking these individual behavior patterns into account, it will be possible to achieve a holistic assessment of the performance of an off-road vehicle, considered as a human operated mobility system. The presented simulation approach – using the simulation tool WINMAKU? in its newest release – accommodates the wide range of possible human influences on off-road vehicle performance to enable optimized tactical mission planning and to analyze operational mission passing. It shows the significant impact of human reactions and decisions on off-road mobility and is therefore also a useful tool for vehicle designing as well as for operator training. Title: “A Multi-Body Model of an Agricultural Tractor for Driving Dynamics Analysis” Author(s): Bojan Ferhadbegovic, Stefan Böttinger and Heinz-Dieter Kutzbach Abstract: The driving speed of modern agricultural tractors increased during last years up to 60 km/h for vehicles with a suspended front axle. The most standard tractors do not have a rear axle suspension, so the tyre is the only suspension element. High vehicle masses, wide tyre inflation pressure range from 0,8 bar up to 2,5 bar, an unfavourable center of mass and sometimes an insufficient adjustment of vehicle components are some of disadvantageous driving dynamics-related attributes of these heavy vehicles. Together with the excitations due to the road unevenness and the tyre run-out, they can lead to some critical vehicle behaviour, especially during high speed cornering. To be able to predict such situations at an early stage of development, multi-body simulation can be used. In this paper, a multi-body model of an agricultural tractor is presented. It is created in SIMPACK and uses the Hohenheim Tyre Model, which is built up in MATLAB/Simulink. For the validation, various handling tests and the corresponding simulation runs were done and some are presented here. The application of the Hohenheim Tyre Model to a handling simulation model of agricultural tractors on firm surfaces produced very accurate results and can subsequently be used for further driving dynamics analysis. Title: “Modeling and Validation of Hitch Loading Effects on Tractor Yaw Dynamics” Author(s): David Bevly, Paul Pearson and Randy Raper Abstract: This paper develops a yaw dynamic model for a farm tractor with a hitched implement, which can be used to understand the effect of tractor handling characteristics for design applications as well as for new automated steering control systems. Dynamic equations which use a tire-like model to capture the characteristics of the implement are found to adequately describe the tractor-implement yaw dynamics. This model is termed the “3-wheeled” Bicycle Model since it uses an additional wheel (from the traditional bicycle model used to capture lateral dynamics of passenger vehicles) to account for the implement forces. The model only includes effects of lateral forces as it neglects differential longitudinal or draft forces between inner and outer sides of the vehicle. Experiments are taken to verify the hitch model using a three-dimensional force dynamometer. This data shows the implement forces are indeed proportional to lateral velocity and that differential draft forces can be neglected as derived in the “3-wheeled” Bicycle Model. Steady state and dynamic steering data are used for implements at varying depths and speeds to quantify the variation in the hitch loading. The dynamic data is used to form empirical transfer function estimates (ETFEs) of the implements and depths in order to determine the coefficients used in the “3-wheeled” Bicycle Model. As shown, changes in a single parameter, called the hitch cornering stiffness, can capture the various implement configurations. Finally, a model that includes front wheel drive forces is derived. Experiments are taken which provide a preliminary look into the effect of four-wheel drive traction forces, and show a difference with two-wheel drive versus four-wheel drive, on the yaw dynamics of a tractor with the hitched implement. Title: “Co-simulation Environment for Vehicle-Powertrain-Tire On/Off Road Analysis” Author(s): Ilinca Stanciulescu, Makarand Datar and Dan Negrut Abstract: The use of virtual prototyping early in the design stage of a product gains popularity due to reduced cost and time to market. The state of the art in vehicle simulation has reached a level where full vehicles are analyzed through simulation but major difficulties continue to be present in interfacing the vehicle model with accurate powertrain models and in developing adequate formulations for the contact between tire and terrain (specifically, scenarios such as tire sliding on ice and rolling on sand or other very deformable surfaces face significant numerical challenges). The proposed work focuses on developing an environment for vehicle simulation by combining several simulation packages for vehicle simulation, tire simulation, and powertrain simulation. The long-term goal of this project consists in promoting the Digital Car idea through the development of a reliable and robust simulation capability that will enhance the understanding and control of the off-road vehicle performance. To this end we concentrate our attention on two main aspects: (1) development of a family of tire and contact models suitable for simulations ranging from high-accuracy to real-time for on/off-road conditions and extreme environments, and (2) investigation of co-simulation techniques suitable from a numerical standpoint to support long-time investigation of heterogeneous systems such as vehicle, tire, terrain, powertrain, and controls. Title: “Some Improvements on Soil-Tire Interaction Analysis by FE-DEM” Author(s): Hiroshi Nakashima and Yuzuru Takatsu Abstract: The Application of Discrete Element Method (DEM) to many practical problems in terramechanics has recently become popular with rapid enhancement of CPU performance in PCs. Thus the precise soil-wheel interaction analysis will be realized within a few years. One of the typical interaction problems is soil-tire system and we have already proposed the combination of Finite Element Method (FEM) for tire and bottom soil layer and DEM for top soil layer to decrease the total simulation time. In principle, the analysis by dynamic FE-DEM can easily be executed, but at the contact interface between FEM and DEM, we experienced partly erroneous result which was introduced by a simple algorithm of contact detection at FE-DEM boundaries. Therefore, we modified our formerly developed FE-DEM program for soil-tire system interactions with the following special attention; (i) precise rebound scheme of a tire deformation after detachment of tire-soil contact, (ii) contact detection algorithm for some erroneous contacting modes at FE-DEM interface, and (iii) fast analysis without loosing the cost of calculation in terms of relationship between the modifications of program and accuracy in obtained result. Result of numerical experiment showed that the above points were sufficiently fulfilled. Title: “The Direct Assessment of Virgin Compression Line Parameters to Enable the Prediction of Soil Density Change Resulting from Agricultural Tires” Author(s): Dirk Ansorge and Richard J. Godwin Abstract: This paper demonstrates the determination of the virgin compression line parameters from initial soil density, contact pressure and resulting rut depth in uniform soil conditions for which a constant soil density change to a depth of 500 mm was obtained in soil bin experiments (whereby total soil depth was 750 mm). The density change was determined with a novel “non - invasive” technique determining soil displacement (strain) which was achieved by placing talcum powder lines into the soil during preparation of the soil bin and measuring the change in their relative position. The soil compaction model COMPSOIL with these parameters predicted wheel rut depth to within +/- 5 %, from which in turn an absolute soil density increase can be determined to within +/- 3 %. The model was successfully validated against data for uniform initial densities of 1.2 g/cm3 and 1.6 g/cm3 and a simulated layered field condition. The estimation of the virgin compression line was validated in the field as well. The parameters of the virgin compression line were estimated using soil density change data for the corresponding average contact pressures of different tires with loads of 4.5 – 10.5 t. Title: “Optical Measurement of Soil Penetration Resistance and Automatic Determination of Rating Cone Index” Author(s): Sergey Sandomirsky, Alan Anderson, Gajendra Savant and Michael Naumov Abstract: This paper describes the automatic Optical Measurement of Soil Penetration Resistance (OMOPR) system for optical measurement of soil bearing capacity (SBC) and results of its application. Among other environmental factors SBC is a critical mechanical characteristic of soil for estimating trafficability and thus the training capacity of sites on which the Department of Defense (DoD) plans to conduct military activity. The challenge is that SBC cannot be measured without mechanical interaction between the soil and a probe. Currently, SBC is characterized by cone index, which is a tedious, low accurate procedure conducted manually by two persons. The OMOPR system consisting of an array of laser optical triangulation sensors installed on an all-terrain vehicle (HUMVEE) measures soil reaction (track depth) on the load provided by the moving vehicle. Additionally, the system evaluates condition of ground vegetation by calculating normalized differential vegetation index (NDVI) from spectrometric measurements. The battery driven OMOPR system operates under computer control and is integrated with GPS receiver allowing for real time mapping of soil bearing capacity. The OMOPR system was demonstrated at Yuma Proving Ground and validated against manual measures of cone index. The system optically measured track depth and showed significant correlation with cone index values. The OMOPR system eliminates a bottleneck in automation of terrain trafficability evaluation. The system enhances efficiency of planning military activity and minimizes its environmental impact on terrain. Title: “Numerical Analysis for Cone Penetration of Mesoscopic Soil Model” Author(s): Hiroshi Nakashima, Takayuki Konishi and Yusuke Toki Abstract: Cone penetration is one of fundamental evaluation methods for soil strength in geotechnical engineering and in terramechanics. We focused on a simple mechanism of cone penetration and proposed a special approach called mesoscopic soil model, by which we could develop a precise numerical model by Discrete Element Method (DEM) even at an intermediate scale of element diameters without sacrificing the accuracy of analysis. Along with the experiments on mesoscopic soil model, we developed an original 3D DEM program for cone penetration analysis. The result of DEM analysis on cone penetration resistance for mesoscopic soil model showed that the program had sufficient accuracy in the simulation of penetration resistance. When the simulation of cone penetration for sand is attempted, not only the spring constants but also the elemental density should be adjusted to obtain similar result as in the experiment. Further modification such as inclusion of rolling friction should be added in terms of highly accurate 3D analysis. Title: “Some Experimental Observations on Cone Penetration of Mesoscopic Soil Model” Author(s): Hiroshi Nakashima, Yusuke Toki and Takayuki Konishi Abstract: Cone penetration is one of fundamental evaluation methods for soil strength in geotechnical engineering and in terramechanics. We focused on a simple mechanism of cone penetration and proposed a special approach called mesoscopic soil model, by which we could expect the development of a precise numerical model with Discrete Element Method (DEM) even at an intermediate scale of element diameters without losing the accuracy of analysis. In this study, we conducted some experiments on cone penetration to mesoscopic soil model. Materials such as alumina and glass were used for regular spherical particle shape for the model. We also tried an aluminum rivet as an irregular particle shape for a mesoscopic model. Moreover, as a reference, we applied the cone penetration to Toyoura sand. The result showed that (i) there is no dependency of penetration rate up to 10 mm/s; (ii) the small diameter of mesoscopic soil model reduced the fluctuations in penetration resistance curves; (iii) the difference of particle shape in mesoscopic soil model did not affect the levels of penetration resistance; (iv) the aluminum rivet model showed the same levels of porosity as in case of Toyoura sand; and (v) it may be possible to use the penetration depth-resistance relationship of mesoscopic model by aluminum rivet to predict a penetration resistance relationship of Toyoura sand at the same porosity by multiplying an appropriate coefficient to the penetration resistance of MSM. Title: “Pseudo-Dynamic Vehicle-Terrain Interaction Tests: A Feasibility Study” Author(s): Hidenori Murakami, Junya Yamakawa and Keiji Watanabe Abstract: New vehicle-terrain interaction tests are proposed to measure terrain interaction forces and couples that are exerted on each wheel of a moving vehicle at each time step. The methodology mimics pseudo-dynamic structural tests that have been successfully conducted to measure seismic response of buildings since the mid 1970s. The pseudo-dynamic vehicle tests utilize both a virtual vehicle in a computer, represented by vehicle equations of motion and displacement-controlled wheel loading apparatus installed in a field or in a soil bin. At each time step, each wheel position on a selected terrain is prescribed by the vehicle equations of motion. For a given wheel position, the terrain interaction force and couple that act on the wheel are measured. In the computer, the measured interaction forces and couples are utilized to explicitly integrate the equations of motion to give the new wheel positions for the next time step. By repeating the process, vehicle-terrain interaction tests are conducted pseudo-dynamically by only using wheels in displacement-controlled wheel loading apparatus. In this paper, both theoretical framework of the pseudo-dynamic vehicle-terrain interaction tests and preliminary experimental data are presented. Title: “Study on Agitation Torque of Excavated Soils and Additives in the Soil-Recycling Machine” Author(s): Hiroshi Takahashi and Yasuo Mori Abstract: A soil-recycling machine has been receiving considerable attention in order to recycle the excavated soils produced from the construction sites. Recently, this machine is also used to remediate the contaminated soils. In this study, the theoretical model to estimate the agitation torque to mix the excavated soils and additives was proposed based on the visualization results of soil behavior. Furthermore, the agitation torque was measured under several conditions. It was confirmed through the comparison between calculated results and experimental ones that the model proposed here was almost reasonable. Title: “Single Wheel Test to Elucidate the Mechanism of Vehicles Driving with Cyclic Steering on Dry Sand” Author(s): Junya Yamakawa, E. Natsagdorj, Keiji Watanabe and Hidenori Murakami Abstract: The effect of right-and-left periodic steering was investigated for vehicles traveling on dry sand. Model size single wheel equipment was constructed to measure the interaction between the driving wheel and sand. Conducting experiment on dry uniformly flatten Toyoura standard sand, the sinkage of the wheel and the pressure on the tire tread was measured. The experimental data showed that periodic steering drive has an effect to reduce the sinkage of wheel into sand and to heighten the pressure at the tire tread compared with the wheel driving in straight. Title: “Dynamic Interaction of Soil and a Steel Roller for Landmine Neutralization” Author(s): Jude Liu and Radhey Lal Kushwaha Abstract: Steel rollers are being popularly used for neutralization of antipersonnel and antitank landmines. Rollers neutralize buried landmines by transferring force from the ground surface to sub-soil. A steel roller with smooth surface was tested in an indoor soil bin. Sub-soil forces and displacements were measured using load cells and displacement sensors at depths of 50, 100, 150, and 200mm. Experimental variables were roller travel speed and the vertical load of the roller. Three travel speeds, 1, 3, and 5 km/h and three vertical loads: 20, 40, and 60 kN were tested. Sub-soil forces and displacement were measured at roller operations of a single pass and multiple passes. The profiles of sub-soil force and displacement for the soil conditions used were then established. For multiple passes, sub-soil forces were increased by 30% if vertical load increased by 50%; while the roller draft increased by 20%. For a single pass, no significant differences detected between the sub-soil forces at speeds of 1 and 3 km/h; when the roller traveled at 5 km/h with a vertical load of 60kN, the sub-soil force was approximately reduced by 30% compared to those at lower travel speeds. For both single and multiple passes, increasing travel speed did not significantly increase sub-soil forces and displacement below 150-mm depth; however, the power required to drive the roller was significantly increased. Higher travel speed was more efficient in creating larger sub-soil displacement and forces within 100-mm of the soil surface. For similar effects below 100-mm, lower travel speed was found appropriate. Title: “Vegetation Recovery Rates after Military Training” Author(s): Heidi R. Howard, Paul D. Ayers and Katie J. Simmons Abstract: Military vehicle maneuvers are know to detrimentally impact natural resource and the quality of the training environment. Recovery rates for biological systems exposed to intensive military training are lacking. An understanding of recovery rates after training events is essential for estimating training land carrying capacity. In this paper, we propose an approach for estimating recovery rates. Studies were conducted on grasslands at Fort Irwin, Washington to evaluate long-term site recovery from military vehicle impacts. Controlled plots were established and exposed to light armored vehicle (LAV) performing typical maneuvers. Data collection and analysis was conducted over a 5-year period. Results indicate that vegetation recovery is directly proportional to soil moisture, vehicle properties and turning radius. The study provides baseline data that will be used to evaluate and determine environmental consequences over time of training activities across ecosystems. Title: “Influence of Turning Radius on Military Vehicle Induced Rut Formation” Author(s): Kun Liu, Paul Ayers, Heidi Howard and Alan Anderson Abstract: A rut is a depression or groove formed into ground by the travel of wheels and tracks. Ruts can cause severe influence on soil and vegetation, and reduce vehicle mobility. In this paper, rut depth and rut width were used as the main indicators to quantify a rut. A new indicator rut index was proposed, combining rut depth and rut width. A Light Armored Vehicle (LAV) and a High Mobility Multi-purpose Wheeled Vehicle (HMMWV) were used for testing the influence of turning radius on rut depth, rut width and rut index. The LAV and HMMWV were operated in spiral patterns at different speeds. Differential GPS data for the vehicle were collected every second during the spiral. Rut measurements were manually taken every 4 to 7 meters along each of the spiral tracks. The results of field test show that rut depth, rut width and rut index increase with the decrease of turning radius. Velocity had effect on LAV rut formation when soil strength was high. No ruts were formed at the low speed of 4.13 m/s. Velocity had almost no effect on the HMMWV rut formation. Title: “Assessing Vehicle Impacts at Multiple Scales on US Army Installations, Example Using Fort Riley, Kansas” Author(s): Alan B. Anderson, Paul D. Ayers, Guangxing Wang, et. al. Abstract: The use of vehicles during military training activities results in soil disturbance and vegetation loss. The capacity of lands to sustain training is a function of the sensitivity of lands to activities, natural recovery rates, vehicle characteristics, and the doctrine which establishes how weapon systems are used. An approach is provided for collecting vehicle impact data to more effectively support impact assessments. The approach combines historic land condition data that quantifies long-term cumulative disturbance patterns, vehicle tracking systems (VTS) that quantify short-term individual vehicle and unit impact patterns, and combines information from both sources to predict future cumulative impacts based on projected training loads. The approach utilizing historic long-term cumulative, short-term individual vehicle impact assessments and projected future training impacts provides the foundation for comparing and contrasting alternative land use scenarios at multiple spatial and temporal scales. Permanent field transects and remote sensed images are used to quantify long-term cumulative vehicle impact patterns. A conditional co-simulation algorithm is used to generate time series maps of vehicle disturbance. Vehicle training load is quantified and combined with land condition estimates to quantify vegetation cover values based on projected training loads. VTS are used to assess short-term impacts by tracking vehicle location and operating characteristics (i.e. turning radius and velocity). Controlled courses are used to establish a range of vehicle dynamic properties. Impacts associated with vehicle use are measured along the vehicle course, and statistical models are developed from the field data to predict vehicle impacts. Vehicle tracking systems are then used to track vehicles during training exercises. Vehicle property and location information are used with statistical impact models to predict the cumulative impact of training exercises. Information from the historic impact assessment and VTS are used to parameterize the Army Training and Testing Area Carrying Capacity (ATTACC) model. The ATTACC model predicts future land condition based on 1) current land condition, 2) projected training loads based on training doctrine and unit stationing, and 3) impacts associated with projected training activities. Title: “Modeling Military Vehicle Terrain Impacts” Author(s): Paul Ayers, Matt Rice, Qinghe Li, et. al. Abstract: Military vehicle traffic during training exercises can severely damage vegetation, producing increased erosion potential. Modeling the terrain impact for wheeled vehicles provides an opportunity to predict vegetative impacts during off-road maneuvers. The theoretical model utilizes the vehicle dimensions, turning radius and velocity to predict terrain contact width and degree of vegetative impacts. Field test-derived vehicle impact model was developed for an eight-wheel Light Armored Vehicle (LAV). Applications of vehicle-terrain impact models for the prediction of eight-wheel Strykers terrain impacts at Fort Lewis Military Installation using GPS-tracking data have been addressed. On average, about 200 square meters of vegetation was removed per vehicle per day. The vegetative impacts estimated from the theoretical and field test-derived vehicle impact models were within 11%. Title: “Desert Terrain Characterization of Landforms and Surface Cover within Vehicle Test Courses at U.S. Army Yuma Proving Ground, USA” Author(s): Steven N. Bacon, Eric V. McDonald, Sophie E. Baker, Todd G. Caldwell, et. al. Abstract: The U.S. Army Proving Ground (YPG) is the Department of Defense (DoD) desert environment test center. YPG has ~320 km of unpaved vehicle test courses that cross a variety of landforms of diverse geologic age and characteristics. The surface cover of the courses ranges from bedrock to silt and their topography varies from steep and rolling to flat. Research presented here aims to provide systematic characterization of the terrain of eight vehicle endurance and three dust courses so that their comparability with other desert areas of the world may be assessed. Landform and surface cover (upper 1 m) characterization was accomplished by geomorphic mapping based on 1-meter resolution IKONOS satellite imagery and field verification, and by assimilating mapping results with pre-existing soil surveys and geologic maps. Results provide a science-based assessment of each test course, including information on the geology, landform type, soil cover, degree of desert pavement development, and dust emission potential. Data in each of these categories is presented both on individual maps for each course and in the form of tabulated data for each official milepost marker along the courses. The results for one course area and an example of how they may be used to assess comparability with another desert of strategic interest are presented here. This work will help to improve the fidelity of desert testing during material Research, Development, Testing and Evaluation (RDTAE) prior to deployment in the field. Title: “Modeling Desert Pavement Deterioration due to Heavy Vehicle Traffic” Author(s): Markus Berli, Todd G. Caldwell, Eric V. McDonald and Daniel A. Gilewitch Abstract: Terramechanics of desert pavements is of increasing interest for military and civilian off-road vehicle operations as well as soil protection and remediation activities. Fine-textured desert pavements are characterized by their pronounced secondary structure, formed in the course of geologic time due to aggregation of desert dust or segregation of primary soil material to peds. This secondary soil structure deteriorates when subjected to intensive vehicle traffic resulting in a lunar dust like material of decreased stiffness and strength as well as hydraulic properties which leads to decreasing trafficability and visibility as well as negative environmental impacts like fast and deep soil erosion. The goal of this study was to model the deterioration of desert pavement with distinct secondary structure due to heavy vehicle traffic. Analytical Terzaghi- and Bekker-type models were used to predict onset and evolution of rut formation within a fine-textured desert pavement due to multiple passes of an eight-wheeled “Stryker” vehicle. For model evaluation, rut depth and soil bulk density measurements from traffic experiments at Yuma Proving Ground (YPG) were used. We found that onset and evolution of (initial) rut formation can be simulated reasonably well with the Terzaghi and Bekker model. Key issues are the correct soil mechanical input parameters for the respective models. Terzaghi’s bearing capacity model is very sensitive to the angle of internal friction and small differences in lead to considerably different predicted bearing capacities. Bekker’s rut depth model is sensitive to its deformation moduli and , which have to be determined for undisturbed soil to avoid overestimation of rut formation on desert pavements. Comparison of measurements and modeling show that pavement deterioration due to rut formation probably consists of two parallel processes: (a) compaction of the soil at the first vehicle pass and (b) predominantly soil surface wear (“abrasion”) due shear stresses at the tire-soil-interface for subsequent passes. For multiple passes rut depth increases linearly at an average rate of 0.75 mm per wheel and 3 mm per vehicle pass, respectively. Yuma soil aggregates show a high sensitivity to “wear” when being “rubbed” e.g. with a cloth or between fingers, even though they have very high aggregate cohesion with respect to axial load. Title: “The Development and Validation of a Terrain Severity Measurement System” Author(s): Nicholas Dembski, Ahmed Soliman, Giorgio Rizzoni, et. al. Abstract: The need for measuring road profiles is useful for many purposes, from the determination of road conditions, to the territory mapping, and so on. A terrain severity measurement system utilizing non-contact optical scanning laser technologies employed in on-road profiling has been developed to make detailed measurements of the relative smoothness of all types of terrain from paved roads to extreme off-road conditions. The objectives included operation in all climatic conditions, simplified operation, and rapid availability of data. Accelerometers and an Inertial Measurement Unit (IMU) are used to measure laser sensor movement in order to eliminate measurement errors due to vehicle pitch and roll. A GPS receiver is used in tandem with the IMU in order to correlate terrain profile information to position and elevation data. The end result is an accurate description of the longitudinal and lateral terrain profile that can be used to characterize the terrain and within vehicle modeling and simulation programs. This approach has been validated over a set of simple bump events. Title: “Development of a 3-D Vehicle-Terrain Measurement System Part I: Equipment Setup” Author(s): Joshua V. Kern and John B. Ferris Abstract: The ability to measure road profiles has progressed over the last four decades from response type systems to vehicle independent systems. Response type systems, such as a road following wheel, characterized a road based on vehicle responses such as spindle accelerations and loads. More recently, vehicle independent systems that employ single point lasers have been used to measure the road surface. Although a great deal of work has been done to refine these systems in the past 20 years, the work developed in this paper is the first to break from these established techniques creating a new level of fidelity, resolution, and applications in terrain measurement. First, the system is developed for both highway applications and off-road terrain, whereas current road profiling systems are only suited for smoother highway applications. Second, the system is capable of measuring terrain in three dimensions, on a grid of approximately 5mm in the horizontal plane, over a width of 4 meters. Current systems measure separate 2-D profiles, typically acquiring one in each wheel path of the host vehicle. Third, the longitudinal distance traveled is now calculated with 2 cm accuracy solely using GPS technology, even over long trials of 10 km or more. Current systems are limited by wheel sensor measurements (meters per rotation) or integrated speed sensor data where accuracies are often quoted as 0.1% (i.e., 10 meters of error in a 10 km trial). It is only by increasing the fidelity and resolution of terrain topology data that application of these data can be advanced. For example, 3-D tire models and terramechanics models require detailed knowledge about the terrain topology that this system can provide. This system is an enabling technology to pursue more advanced terrain modeling analyses, such as kriging. Ultimately, the knowledge of how the data are acquired can lead to insights into advanced applications of the data. Title: “Development of a 3-D Vehicle-Terrain Measurement System Part II: Signal Processing and Validation” Author(s): Shannon M. Wagner, Joshua V. Kern, Wescott B. Israel and John B. Ferris Abstract: During the development of an automotive chassis, load data representing severe customer usage is needed to test the vehicle. The majority of these loads originate from the excitations of the vehicle from the road; therefore, a well defined terrain profile is needed for simulation purposes. Currently, terrain profiling technology includes the use of vehicle mounted lasers to acquire the topological data. The profile data is measured relative to the laser’s moving reference frame as the vehicle traverses the terrain. This necessitates the removal of the vehicle’s body motion from the laser acquired data. This work examines one such 3-D terrain measurement system in which an augmented Inertial Navigation System (INS) is used to estimate the vehicle’s position and orientation at every instant in time. This work examines the methodology of synchronizing the separate data acquisition systems and developing an augmented INS solution to improve the estimate of the vehicle’s true position and orientation. The result of using these improved estimates in this common mode rejection problem is validated in a series of studies. The validation studies examine the precision of the terrain measurements in the vertical direction and in the horizontal plane. Through these studies, it is demonstrated that very high precision can be achieved using these signal processing techniques. Title: “Methods of Simulation of Terrain Profiles” Author(s): T. C. Sun, Milton Chaika, David Gorsich, et. al. Abstract: We propose 4 statistical methods to simulate terrain profiles. For the profiles which are Gaussian and have a linear structure, we find that the uniformly modulated process (UMP) is a good model for simulation. For nonlinear and non-Gaussian profiles, we can use the empirical mode decomposition method (EMD) to decomposition the profile data into components of intrinsic mode functions and then model each component separately. Also we can model the profile data by an ARMA process and then model the residuals from the ARMA process by a GARCH model. This method works well for some cases. For profiles which haves bumps intermittently, we can use the threshold autoregressive (TAR) method to model the profiles with bumps by using a threshold which can switch back and forward from the regular profile to the bumps. The methods are applied to data collected from Belgian Block and Perryman3 tracks. Title: “Modeling of Moguls on an Endurance Test Course” Author(s): Mark J. Brudnak, David D. Gunter and Wesley Bylsma Abstract: This paper presents an approach to modeling discrete features on a U.S. Army endurance test course. The features in this case are 39 moguls with heights varying between 0.36 and 0.63 m built into a portion of the course. Because they are enumerable and localized, they do not lend themselves to traditional modeling techniques such as RMS, PSD, IRI, etc. We assume that the mogul has a well defined, ideal shape superimposed with stationary noise for which we evaluate five different modeling approaches. The models that we evaluate are the Gaussian function, the Hanning window, the support vector machine, a two-Gaussian function and a two-Gaussian function with fixed width and amplitude ratios. We evaluate these models by computing the RMS error of each best fit and by evaluating the stationarity of the residue. We further evaluate each mogul model by running a HMMWV dynamics model over each and comparing several responses to those obtained from the profiled mogul. In our analysis we find that a model consisting of two Gaussian functions with related widths and amplitudes yields an unbiased estimate of a mogul and can be made to approximate any mogul by adjusting its width and amplitude. Title: “Comparison of In-Cylinder Pressure Measurement Based Engine Torque Data for a GTL Synthetic Diesel and Conventional Diesel Fuel” Author(s): Chuen-Sen Lin Abstract: Along with depleting petroleum reserves and increasing fuel prices, the abundance of natural gas resources on earth may make gas to liquid (GTL) fuels one of the important substitutes of the petroleum fuels. GTL synthetic fuels have been presented in literature to have better performance in energy efficiency and emissions in comparison with the petroleum based diesel fuels. However, there are significant differences in the composition and properties of GTL and conventional diesel fuels. Since, the fuel properties have significant effect on the engine power and torque produced and thus on the vehicles traction, it is necessary to further investigate the possible effects of using these GTL fuels on vehicle performance. This paper presents a comparison of the measured in-cylinder pressure based engine torque data of a GTL synthetic diesel and conventional diesel fuel obtained on a constant speed DD50 diesel generator. Comparison results are presented for various loads and different injection timings. A detailed discussion about the possible effects of GTL synthetic diesel fuels on the vehicle performance is also presented based on the observation of the fuel’s combustion performance at various operating conditions. Title: “Instrumenting an All-Terrain Vehicle for Off-Road Mobility Analysis” Author(s): Kyle D. Wesson, Michael W. Parker, Sally A. Shoop, et. al. Abstract: With the need for smaller vehicles, even robots, in future military operations, understanding small vehicle mobility is essential for their success in field operations. Researchers at the Cold Regions Research and Engineering Laboratory instrumented an all-terrain vehicle (ATV) with mobility sensors to begin the work of characterizing and understanding small-vehicle mobility in all seasons. After installing the sensors, tests were performed at the Vermont National Guard’s Ethan Allen Firing Range to validate the installation and assess the ATV’s terrain-vehicle interaction. This paper presents one manner to instrument an ATV with portable and inexpensive mobility sensors and describes the testing methodology and results. Low-cost, portable vehicle mobility instrumentation systems would allow for the creation of accurate vehicle simulations and mobility awareness that can be used in situ by the warfighter and lead to further applications of all-terrain vehicles in force protection and border patrol scenarios. Title: “Ride Comfort of Agricultural Tractors - Objective Measurements and Subjective Evaluation” Author(s): Jürgen Haberland, Stefan Böttinger and Christian Brinkmann Abstract: Whole-body vibration of agricultural tractor operators has a great influence on the perception of ride comfort. While measurements of acceleration levels deliver an objective representation of vibration intensities expressed in numerical values ride comfort may be described also through subjective perception of the operator itself. Four different test types with an agricultural tractor operated by a group of seven test persons with varying features were carried out in order to examine interrelations between objective measurements and subjective evaluation of ride comfort. Two test types included the excitation of the vehicle with a mounted shaker device to determine the perception threshold of the test persons. Two other test types comprised test rides at different vehicle ground speeds without excitation of the shaker device. Signals of accelerometers mounted to the tractor were analyzed in the time and frequency domain using frequency weighting functions. Subjective evaluation of ride comfort was documented using appropriate questionnaires. The acceleration data, subjective evaluation as well as the vehicle driving speed served as inputs for a correlation analysis routine. There were found a number of high correlations between the frequency weighted acceleration signals and the associated subjective evaluation though the correlation quality varied within the group of test persons. It can be concluded that also non professional test drivers are capable to evaluate different types of vehicle vibration. Title: “Determination of Rolling Resistance Components” Author(s): Péter Kiss and Lajos Laib Abstract: One of the major sources of loss when a vehicle is traversing terrain – especially on soft soil – is rolling resistance. Many workers have attempted theoretical and practical definitions of this. They have usually examined the magnitude of the deformation of tire and soil during rolling under steady-state conditions. However, the magnitude of rolling resistance continually varies during motion. The unevenness of the terrain and the inhomogeneity of the soil give rise to substantial vertical vibrations which change the magnitude of deformations, and thus rolling resistance. The effect of these vibrations must therefore be taken into account. This paper reports a determination of rolling resistance components through field experiments designed to distinguish rolling resistance losses from other tire-soil interaction losses (slip). Soil and tire deformation losses were determined separately. The experiment involved measurement of vertical acceleration at the wheel center. The acceleration and mass data yielded the dynamic load which is superposed on the static weight of the vehicle and continually alters the magnitude of the soil and tire deformation and thus the rolling resistance. The test results permitted four components of rolling resistance to be determined. These are (1) soil deformation, (2) tire deformation, (3) the additional soil deformation caused by the dynamic load and (4) the additional tire deformation from the same cause. Tire deformation was responsible for 39% and soil deformation for 37% of rolling resistance in the experimental vehicle and soil conditions. The additional tire losses accounted for 5% of rolling resistance and the additional soil losses 8%. The remaining 11% of rolling resistance consisted of other – individually negligible – losses such as air resistance, which were not separately distinguished. The measurements were checked against energy (power) measurements from torque and speed sensors, and these confirmed the rolling resistance calculations. Title: “Design and Development of Valve Train System for Terrain Vehicle Engine Using GT-SUITE Software” Author(s): A.K.M. Mohiuddin, Ataur Rahman and Asral Fikri Abstract: GT-VTRAIN, a multi-purpose simulation tool for the mechanical design analysis of valve train systems is used to develop the system. GT-VTRAIN is one of the six solvers of GT-SUITE. There are two ways of solving models in GT-VTRAIN, either through a backward solution or a forward solution. The backward solution is an exact solution where the cam shape is calculated based on a known follower lift or valve lift. In contrast, the forward solution is an iterative solution where the follower lift and valve lift are calculated based on a known cam shape. The backward solution is used to generate the cam profile from the known lift profile (direct acting). Five valve lift profiles were generated with the aid of the software. The five designs have the same maximum lift and duration but they differ in terms of intensity or aggression. The numerical differentiation of the valve lift-degree profile will produce a velocity-degree curve; the differentiation of the velocity-degree curve gives an acceleration-degree profile; and the differentiation of the acceleration-degree curve gives the jerk-degree characteristics. The design goal is to use a valve lift profile that is as aggressive as possible (higher acceleration) so as to achieve superior engine breathing characteristics, but it must be done within the mechanical limitations of the engine design. A lift-duration envelope ratio which is the area under the valve lift curve divided by that of the rectangle in which it sits is defined to judge the ‘aggression’, or otherwise, of a valve lift profile. The cam design feature of VT-Design is an interactive cam design tool used to generate a smooth cam or lift profile using a multiple-polynomial scheme that meets the desired specifications such as the duration of the cam event, maximum lift, and maximum accelerations. High quality smoothing technique is crucial to avoid the components from being subjected to unnecessary high stress levels or unnecessary high power to drive them. Title: “Estimation of Net Traction for Differential-Steered Wheeled Robots” Author(s): Laura Ray, Devin Brande and James H. Lever Abstract: We present a method for estimating the net traction and resistive wheel torques for a suspensionless, differential-steered robot on rigid or deformable terrain. The method, based on extended Kalman-Bucy filtering (EKBF), determines time histories of net traction and resistive wheel torques and wheel slips during steady or transient maneuvers. This method assumes good knowledge of the vehicle dynamics and treats the unknown forces and moments due to terrain response as random variables to be estimated. A proprioceptive sensor suite renders a subset of the unknown forces and associated wheel slip and slip angles observable. This methodology decouples semi-empirical terramechanics models from the net effect of the vehicle-terrain interaction, namely the net traction developed by the vehicle on the terrain. By collecting sensor data and processing data off-line, force-slip characteristics are identified irrespective of the underlying terramechanics. These characteristics can in turn support development or validation of terramechanics models for the vehicle-terrain system. For autonomous robots, real-time estimates of force-slip characteristics can provide setpoints for traction control, increasing vehicle performance, speed, and maneuverability. Finally, force-slip estimation is the first step in identifying terrain parameters during normal maneuvering. The methodology is demonstrated through both simulation and experimental data for a 13-kg robot. Title: “Concept of Light Autonomous Machines for Dual Use” Author(s): Dinko Mikulic, Vladimir Koroman, Davorin Ambrus and Vjekoslav Majetic Abstract: This article describes the family of light machines for dual use. Demining machines are used for neutralization of mine obstacles in open and urban mine contaminated areas. By changing the working tool, these machines can be used to perform other work in endangered areas or for commercial purposes, i.e. soil or mine ore excavation work, etc. Unmanned platform is based on 5 ton tracked machine with hydrostatic or diesel – electric power transmission. Working device is rotating telescopic arm with required reach, which can accommodate different tools and sensors: flail, roller, loading shovel, dozer blade, gripper, forks, multi-sensor detectors, etc. Machine removal of mine and similar threats reduces required manpower, preventing injuries and saving lives. Future autonomous machine should reliably perform tasks of heavy counter mine operations and enable development of various intelligent systems for commercial purposes, in order to make the whole project economically feasible. Title: “Collision Detection of Moving Polygonal Mobile Robots” Author(s): Cheng-fu Chen Abstract: The paper addresses the issue of collision detection between two moving polyhedral objects by considering two fundamental questions: how to effectively calculate the proximity between the objects, and what the change is in the calculated proximity when the objects are moving. A linear programming based approach is presented to determine the proximity between two moving polyhedral objects. By utilizing the relative translational and rotational movements between two polyhedral objects as the parameters, we propose a parametric formulation for determining the proximity between two moving polyhedral objects for all the possible changes in the relative configurations between the objects, to predict the change in their proximal relation. Since the parametric formulation and solutions can be conducted in advance, the proximity detection results can be stored as a batch file to facilitate motion planning of robots with collision avoidance that requires real-time collision detection. The effectiveness of the proposed collision detection method is illustrated by one example of controlling a car-like mobile robot to reach its goal while another mobile robot is deliberately designated to interrupt the goal-reaching of the first robot. The proposed method has strength on the batch processing for collision detection, a potential saving in the real-time computation. Title: “Design and Mobility Evaluation of a Tracked Lunar Vehicle” Author(s): Sachiko Wakabayashi, Hitoshi SATO and Shin-Ichiro NISHIDA Abstract: This paper describes the design and the evaluation results of a tracked lunar vehicle, which aims at achieving higher mobility, especially improving climbing ability on pure sand slopes. Slippage and sinkage happen easily on the Moon due to the thick, soft and dry regolith, and past lunar vehicles had difficulty in traveling through soft sand area. To avoid getting stuck, lowering contact pressure is crucial for a lunar mobility system. We designed a tracked vehicle using mesh crawler links to reduce contact pressure as well as reduce complexity, weight and number of parts, while keeping high climbing ability. Single-crawler tests on simulated lunar soil revealed that the crawler’s slip ratio was lower than that of a rigid wheel at any slope angle, and that the crawler’s power consumption was lower than that of the wheels at a slope of 10 degree or more. Furthermore, the crawler’s slip ratio was stable or decreasing along the traveling distance at steep slopes contrary to the case of the wheel. After confirming the single-crawler’s performance, we designed a tracked lunar vehicle, called “Light Crawler”. It is equipped with the four mesh-crawlers, each of which is driven and steered independently, intends to realize both high climbing ability and small turning circle, and with a unique suspension system to climb over an obstacle. The four-crawler vehicle’s climbing ability and obstacle-crossing ability were tested on both simulated lunar soil and rock-scattered field, and the full-configuration performance was successfully confirmed. Title: “Study on a Vane-telescopic Walking Wheel for Lunar Rover” Author(s): Chen Baichao, Wang Rongben, Jin Lisheng, et. al. Abstract: This article proposes a new type of driving wheel for Lunar Rover, which is called as vane-telescopic walking wheel. Based on the interactional relation between wheel and soil, the deepness of the vane inserting into soil can be adjusted automatically. The article describes the wheel’s structure and working principle, analyses the wheel-acting force and deepness of the vane inserting into soil. A simulating model is also established under ADAMS. The mechanism characteristics are analyzed by related simulation. This new type of driving wheels is installed on a prototype lunar rover and its mobility performance is tested. Testing results show that the prototype lunar rover presents better trafficability and ride comfort on the soft and incompact soil. Title: “Development of a Simple Shear Test Apparatus with Low Confining Pressure for a Regolith Simulant ” Author(s): Kazuyoshi Tateyama Abstract: A simple shear test apparatus is developed to measure the shear strength of a regolith simulant under a low level of confining pressure as part of a study on the trafficability of a lunar rover. The apparatus is composed of a tiltable table and a shear box. The table can be inclined at optional angles from the horizontal level, and the shear box is attached to this table. The vertical confining pressure is loaded on a specimen with the weight of cylindrical metal bars, and only the component force parallel to the table surface can be effectively loaded on the specimen as the normal stress. The minimum normal stress that can be loaded on a specimen is 0.7 kN/m2. A series of experiments clarifies that the regolith simulant shows different strength characteristics under a low level of confining pressure from those which follow Coulomb’s failure criterion under a high level of confining pressure. Title: “Numerical Analysis of Sand Flow under Low Gravity Condition” Author(s): Hiroshi Nakashima, Yasuyuki Shioji, Taizo Kobayashi and Shigeru Aoki Abstract: The application of Discrete Element Method (DEM) to practical problems in terramechanics has been popular with rapid enhancement in CPU performance of PCs. Moreover, with the strong motivation of future human stay and of in-situ resource utilization on lunar surface, DEM analysis on moon-related topics has become active in Japan. However, the effect of low gravity on DEM parameters has not yet sufficiently investigated, especially on the treatment of spring constants. Firstly, we conducted the low gravity experiment by parabolic flight of an airplane, where Toyoura sand flowed out from a hopper onto a floor table to form sand pile by its own weight. We obtained results on angle of repose from digital video image data. We could confirm that the effect of gravity condition on the angle of repose of sand was small. Secondly, DEM was applied to this hopper problem and numerical results were compared with experimental results in terms of angle of repose. The result of DEM simulation by using the common spring constants at different gravity condition also showed no dependency of DEM parameters on gravity condition. Therefore, it is concluded that the same values of DEM spring constants decided at 1G condition may be used for the numerical analysis by DEM in low gravity condition such as the case on lunar surface. Title: “Research the Interaction between the Rigid Wheel and the Lunar Soil by DEM” Author(s): Li Jianqiao, Zou Meng, Jia Yang, et. al. Abstract: It is important to research the relationship between the wheel and lunar soil in the circumstances of lunar surface for the lunar rover to work efficiently. Based on analyzing the FEM (Finite Element Method) and DEM (Discrete Element Method), this research considers that the Discrete Element Method is feasible and superior to the Finite Element Method in simulating the interaction between the wheel and the lunar soil. The model of the interaction between the rigid wheel and the lunar soil is setup. The system of soil bin is simulated by means of the software PFC2D. Parameters of the lunar soil for DEM model are confirmed in the biax test,and the mechanical characters of those particles are similar to the lunar soil. Found the Discrete Element Method model of the slip, sinkage, and draw-bar pull, which are checkout by the soil bin test. Comparing the traffic ability of the nonrug-wheel with the rug-wheel, it indicates that the rug-wheel has bigger draw-bar pull and better traffic ability than the nonrug-wheel under enough torque. WRITTEN-ONLY PAPERS 2007-73-0152 Author(s) Info Title: “The Sustainability and Performance of Vehicle Dust Courses for Desert Military Testing” Author(s): Todd G. Caldwell, Eric V. McDonald, Steven N. Bacon and Graham Stullenbarger Abstract: Desert dust has long been recognized as an important parameter for testing military vehicles and equipment due to the potential for adversely affecting performance and durability. Vehicle dust test courses were originally established in areas of heavy underlying fine particulate layers (silt and clay) and used for cyclic tests until depleted of dust by wind erosion and soil mixing. These soils, commonly known as desert pavements or reg soils, are geomorphically old and slowly develop through the trapping of atmospheric dust over tens of thousands of years. The soil is thus both a long-term sink and source for aeolian material. Thus, this dust is a non-renewable resource for the Yuma Proving Ground (YPG), the Army’s primary environmental hot weather test center. There is concern that the continuous utilization of YPG dust test courses has eroded through the overlying dust-rich soil to the extent that the true natural environmental conditions are no longer adequately represented. The overall objectives of this study were to characterize three dust courses at YPG in order to gain a better understanding of the current state of test course soils and the overall sustainability of high dust potential soils needed for military testing. Soil samples collected from both courses and adjacent undisturbed soils, as well as dust collected on tactical vehicles, were analyzed for mineralogy, geochemistry, and physical properties. Results indicate adjacent undisturbed soils exhibit a relatively higher dust potential (higher silt and clay) and elevated reactive salts and carbonates indicating a significant loss of fines from the dust test courses. Routine vehicle traffic and surface preparations have eroded and mixed the dust layer with the underlying sand and gravel-rich horizons, depleting the courses of their dust producing potential. Desert soils have finite dust content when disturbed and therefore there is a finite sustainability of a dust test course. Title: “Modeling and Simulation of In-Plane and Out-of-Plane Forces of Pneumatic Tires on Fresh Snow Based on Finite Element Methods” Author(s): Jonah Lee and Qing Liu Abstract: Significant challenges exist in the prediction of all the interaction forces generated from the interface between pneumatic tires and snow-covered terrains due to the highly nonlinear nature of properties in flexible tires, deformable snow-cover and the contact mechanics at the interface of tire and snow. Operation conditions of tire-snow interaction are affected by many factors, especially interfacial slips, including longitudinal slip (braking or driving), lateral slip (slip angle) and combined longitudinal and lateral slips (such as brake-and-turn and driveand- turn), normal load applied on the wheel, friction coefficient at the interface and snow depth. This paper presents three-dimensional finite element simulation of tire-snow interaction for lowstrength snow under the full-range of controlled longitudinal slip and slip angle for three vertical loads to gain mechanistic insight. The pneumatic tire is modeled using elastic, viscoelastic and hyperelastic material models; and the snow is modeled using the modified Drucker-Prager cap plasticity model. The traction, motion resistance, drawbar pull, snow sinkage, tire deflection, contact pressure and contact shear stresses are obtained under combined slip conditions as well as the wheel states. The predicted results can be further applied to analytical modeling of tire-snow interaction and modeling of full vehicle dynamics for off-terrain conditions. Title: “Utilizing Biomimetic Image Processing to Detect the Road Edge of Off-road Terrain” Author(s): Nancy Truong and William Agassounon Abstract: Soldiers incurred injuries or even lost their lives due to rollovers while driving military vehicles. A recent report identified that the one cause of rollovers is the driver’s inability to assess rollover threats, such as a cliff, soft ground, water, or a culvert on the passenger side of the vehicle, due to the vehicle’s width. To reduce the number of rollover accidents, a road-edge detection and driver warning system is being developed to detect the rollover threats on the passenger side of the vehicle and warn the driver. This system utilizes a unique, ultra-fast image processing algorithm based on the neurobiology of insect vision and the study of fly vision. The system consists of a camera system, a long-range, planar laser scanner, a processing module in which a biomimetic image processor detects edges present in the images in real-time, and a Driver Vision Enhancer (DVE) which displays the current road image, detected boundaries, and road side terrain steepness. Title: “The Effect of Relative Sinkage on Rolling Resistance for the Off-Road Vehicle” Author(s): H. M. El-Zomor, S. M. Shaaban, M. A. El-Nashar and I. M. Ibrahim Abstract: Due to the complexity of modeling off-road mobility, it is required to make more experimental work to predict the vehicle performance on the off-road terrain. Rolling resistance is of primary importance for vehicles as approximately one third or more of the energy consumed by the off-road vehicles used to overcome its effect. This paper deals with experimental laboratory tests to detect the rolling resistance of the pneumatic tires on sandy soil and to introduce a parameter that affect the rolling resistance. Instrumentation and data acquisition system installed on a laboratory test rig have been used to measure the rolling resistance force, sinkage of the tested tire, and the normal load applied to the tested tire. Tyre has been tested for three different inflation pressures and applying the multi-pass technique. The results show that, there is a parameter that affect on the rolling resistance. This parameter is the relative sinkage (z/r). A relation between the rolling resistance and the relative sinkage of the tire obtained and expressed in equation that may be used for more prediction of the rolling resistance in the sandy soils. Title: “Changes in Soil Pore Continuity Indices under Different Controlled Deformation Types” Author(s): M.R. Mosaddeghi, M.A. Hajabbasi and A. Hemmat Abstract: Soil microstructure is an important component of proper functioning for agricultural soils. Deformation definitely affects soil microstructure and pore characteristics, but there are limited reports in this regard. This study was conducted to explore the significance of different deformation regimes in relation to pore continuity indices. The pore continuity indices like ratios of air permeability (Kg) to air-filled porosity (AFP), C1 or to (AFP)2, C2 and logarithmic relation between Kg and AFP quantified by the rate of increase in log [Kg] with an increase in log [AFP], N were obtained. Treatments consisted of five soil series (sandy loam to clay) from Isfahan Province (central Iran), four matric suctions (10, 20, 50 and 80 kPa), three maximum axial stresses (200, 400 and 600 kPa), and two loading types with ten loading cycles. The loading types were confined compression test (CCT) and kneading compression test (KCT). Soil type and matric suction, loading type, maximum applied stress and number of loading cycles significantly affected C1, C2, and N. The changes in C1 and C2 with the maximum axial stress were logarithmic due to their dependency on high-sensitive properties such as pore size distribution and tortuosity. The significant changes in these indices during cyclic loading imply the negative effects of repeated loading on soil microstructure especially at high soil water contents. At low matric suctions (even for the first loading cycle), KCT drastically reduced the C1 and C2 due to smearing/shearing and stress direction changes when compared with CCT. Contrarily, CCT destroyed the soil microstructure at higher matric suctions (i.e. 80 kPa). The C1 is related to pore size distribution and continuity but C2 is only concerned with pore size distribution. Therefore, the different trends in C1 and C2 might be related to pore continuity. The slope of the relation (N) which quantifies the rate of decrease in pore tortuosity with an increase in macropore volume was significantly reduced by cyclic loading. The value of N was also decreased with an increase in soil water content at the time of compaction. Overall, the changes of soil microstructure might not be accounted for by the air-filled porosity but could be adequately determined by the pore continuity indices. Title: “Gas Transport Characteristics as Influenced by Concurrent Loading and Drying/Wetting Processes in Soils with Weak Structure” Author(s): M.R. Mosaddeghi, A. Hemmat and M.A. Hajabbasi Abstract: Agricultural vehicles impose external stresses on soils during tillage and traction. Internal forces originated from water menisci around soil particles could insert some stresses during natural processes, such as drying/wetting cycles. The concurrent influences of these stresses on soil pore characteristics, however, have not been examined intensively. In central parts of Iran, soils are low in organic matter with weak structure and thus naturally hardened. This research was carried out to investigate the concurrent impacts of external loadings and drying/wetting cycles at four matric suctions (10, 20, 50 and 80 kPa) on pore characteristics of five topsoils (sandy loam to clay) from Isfahan Province (central Iran). Loading types consisted of confined compression test (CCT) and kneading compression test (KCT). Each loading type had three maximum stress levels (200, 400 and 600 kPa) with ten cycles. Before starting the loading, a drying/wetting cycle was applied on soil samples. Drying/wetting cycles were applied in between the first and second cycles of loadings. Gas transport characteristics such as ratios of air permeability (Kg) to air-filled porosity (AFP), C1 or to (AFP)2, C2 and logarithmic relation between Kg and AFP quantified by the rate of increase in log [Kg] with an increase in log [AFP], N were examined. Soil pore characteristics were significantly affected by external stresses and internal stresses originated from drying/wetting cycles. There were severe decreases in C1 and C2 due to loading for the silty clay loam soil with weak structure. For this soil, drying/wetting cycle decreased the C1 and C2 at maximum stress of 200 kPa and increased them with stresses of 400 and 600 kPa. For the coarser soils, an increase in C1 and C2 after a drying/wetting cycle was observed due to reformation of menisci around the soil particles in such a way that the soil pore characteristics were improved. For a clay soil with higher organic carbon and stable structure, C1 and C2 were near the values of sandy loam soil due to persistence of inter-aggregate macropores during loading. The C1 and C2 were higher under KCT in comparison with CCT at matric suctions of 50 and 80 kPa. The drying/wetting processes significantly increased N (i.e. decreased pore tortuosity) in most cases although the changes in pore space were not considerable. As a conclusion, pore characteristics of soils, especially with weak structure, could significantly be affected by internal stresses. Title: “Dynamic Control Research of Dual-motor Driven Electric Tracked Vehicle” Author(s): Zou Yuan, Zhang Cheng-ning and Wu Jing-bo Abstract: Puts forwards the fundamental problem of dynamical driving control for dual-motor driven electric tracked vehicle and presents the basic definition in the view of control engineering. Control structure of vehicle is designed and “speed-regulating” and “torque-regulating” dual-motor driven control schemes are designed and compared analytically. The validation of two kinds of dynamic control schemes is proven by field experiment’s results. Title: “Relationship between Soil Pre-compaction Stress and Shear Strength” Author(s): A. Hemmat, M. Tahmasebi, M. Vafaeian and M.R. Mosaddeghi Abstract: Soil pre-compaction stress (?pc) refers to an equivalent maximum stress that acted on the soil in the past. It is generally regarded as the stress where the soil deformation changes from “small, elastic and reversible” to “plastic and therefore irreversible”. It was hypothesized that ?pc is the point at which the shear stress created from the applied forces is equal to the soil shear strength. Therefore, the objectives of this research were 1) to determine the soil ?pc from plate sinkage test (PST) and confined compression test (CCT); and the soil shear strength from shear box test on pre-compacted samples and 2) to obtain the relations between the soil compressive (pre-compaction) strength and shear strength. Tests were conducted on a sandy loam taken from topsoil. Experiments were conducted at two gravimetric water contents: 17% and 19%. Preloading stress ranged from 0 to 200 kPa. The center part of the preloaded soil was submitted to a 50-mm plate sinkage test; then immediately one cylindrical sample was cored for CCT and three undisturbed sampled were taken for a shear test. Sinkage and loading data obtained from the reloading tests were used for calculation of soil ?pc values using Casagrande’s method. The parameters of the Mohr-Coulomb failure line were derived from the shear strength as a function of the applied vertical stresses. The ?pc predicted with PST was accurate, whereas the values, obtained with CCT were 4.5 (for water content of 17 %) and 8.5 (for water content of 19 %) times higher than the applied pre-loading stresses. The results showed that there was a highly significant (R2=0.95**) and linear relation between the soil ?pc values and corresponding soil shear strength for both PST and CCT. Therefore, it might be stated that the ?pc is not at a transition point between small, elastic deformation and large, plastic deformation, but it is located in a transition area in which both types of deformation are occurring at the same time. Title: “Engine Misfire Diagnosis Based on Frequency Domain and Fuzzy Logic” Author(s): Zhenchun Xia, Guozhong Wang, Kazuo Kido and Hiroki Yamaura Abstract: Powertrain diagnosis has been demanded with growth & complexity of powertrain electronic control system and enforcement of law & regulation in the last decades. In regulation OBD II, requirement of misfire monitoring has been demanded much more strictly. A variety of diagnosis methods for misfire have been developed, however most of them either depend greatly on special or expensive sensors or suffer from the disturbance of vibration due to non-misfire reasons. One combination of Fast Fourier Transform (FFT) and fuzzy logic to perform the misfire diagnosis is proposed. It takes full advantage of property of FFT and fuzzy logic, providing accurate and robust detection results, without adding additional hardware diagnosis instruments. Fast Fourier Transform is one powerful tool in frequency domain analysis, which can abstract the specific frequency characteristics of misfire signals during overall engine crankshaft speed fluctuations directly and quickly, and fuzzy logic do a good job of trading off between significance and precision, which can reduce possible false misfire alarm caused by interruption of noise and disturbance of uneven road. The experiment on one 4 cylinders engine proves that the method is effective. Title: “An Investigation into the Rollover Conditions of a Light Off-Road Vehicle with Consideration of Soil-Tire Interaction” Author(s): Mohammad M. Davari, Hojat Noori, Mohammad Khodabakhshian, et. al. Abstract: Nowadays, the use of off-road vehicles like All Terrain Vehicles and buggies are spread generally all over the world and various kinds of these automotives are designed and manufactured. The objective of this paper is to make an investigation into the rollover conditions of a light off-road vehicle. In this research, we interested not only in the dynamic properties of the vehicle, but also soil- tire interaction. As we cannot model the conditions of soil and tire at the time of cornering, for calculating lateral and normal forces, some experiments were done on soil "shear" and "sinkage" tests under several loading conditions in the limits of primary dynamic load before cornering and maximum dynamic load at the time of cornering. So, six parameters of the soil were elicited by analyzing a specific soil. For calculating the lateral force, the plate sinkage test (PST) was done under the calculated load. For reaching the amount of "soil sinkage" under the load and inflation pressure of tire for calculating the normal force, the "sinkage" analysis was done. Eventually, considering the resulted relations between tire and soil, we could end up with an empirical equation that with consideration of soil parameters, it could be used to determine the limitation of lateral acceleration and capability of an off-road vehicle during maneuvering and turning. The result of this paper can be used to promote the safety and increase the stability of off-road vehicles. Title: “Determination of Snow Stress State Under Vehicle Loads” Author(s): Jaroslaw Pytka, Gabriel Szymaniak, Jaroslaw Dabrowski and Robert Rusinek Abstract: Knowing the stress state in soft ground under wheel or track loads is important for wheel-soil or wheel-snow interactions description. Soil stresses can be correlated with vehicle’s parameters and wheel loads and numerical models of wheel-soil interactions can be parametrized on the basis of soil stress state. It is noticeable that soil stress state experimental results are well documented in the literature, while snow stress results are rare or none. The aim of the authors was to 1) develop a method for snow stress determination under vehicle loads; 2) apply the method in a real field experiment to obtain data; 3) analyze the data and conclude of the usefulness of the method. In the paper an experimental method developed by the authors for determination of snow stress state under vehicle loads is described. In the method, a SST (Stress State Transducer) was used for determination of a complete snow stress state: major principal stress S1, minor principal stresses S2 and S3, stresses in the octahedral system: normal MNS and shear OCTSS. Pressure transducers installed in the SST were designed and prepared for winter measurements. They were calibrated in a low temperature chamber. The SST was installed at 30-35 cm depth and wheeled by a 5,6 T 4x4 military truck. Results from the experiments, snow stress curves and peak values were presented and discussed. The concluding remarks are as follows: a) it is possible to determine snow stresses with measuring devices used for soil after some modifications, b) temperature calibration of pressure transducers is essential for measurements precision, c) installation of the SST is of high importance because of possible snow structure damage and its effect on final results. Title: “Development of a Single Wheel Soilbin Testbed for Studying Wheel-Terrain Interaction” Author(s): Dang Zhaolong, Shen Zhenrong and Jia Yang Abstract: Eight successful rovers have been utilized on the Moon and Mars exploration since the first lunar rover Lunokhod 1 traversed over the lunar surface. In January 2004, the project of China’s lunar exploration was approved. Chang’e Project includes three development phases: orbiting about, landing on and returning from the Moon. During the second phases, rovers are required to negotiate lunar terrain. In order to study the mechanics of wheel interacting with terrain, a scheme of single wheel soilbin testbed is described. The components of soilbin testbed are soil bin, mechanical system, measurement and control system. The main parameters are wheel diameter, vertical load, torque, linear velocity and draw pull. The range of wheel diameter is decided by considering present and future lunar or planetary exploration rovers. The vertical load on the wheel is applied by weight blocks. The wheel is directly driven by the electric motor. The linear and the angular velocity of wheel are independently controlled. Vertical load, linear and angular velocity of wheel, wheel torque, and drawbar pull are measured by commercially sensors. Wheel slip ratios can be computed by the linear and angular velocity of the wheel. The establishment of soilbin testbed will help to study the wheel–terrain interaction and accelerate the development of lunar exploration rover.
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