Terramechanics Modeling of Mars Surface Exploration Rovers for Simulation and Parameter Estimation

2011 ◽  
Author(s):  
Karl Iagnemma ◽  
Carmine Senatore ◽  
Brian Trease ◽  
Raymond Arvidson ◽  
Keith Bennett ◽  
...  
Keyword(s):  
Model Parameters ◽  
Climate History ◽  
Mobility Modeling ◽  
Simulation Tools ◽  
Terrain Model ◽  
Ongoing Work ◽  
Surface Exploration ◽  
Terrain Parameters ◽  
A Site ◽  
Surface Geology

In 1997 and 2004, small wheeled robots (“rovers”) landed on the surface of Mars to conduct scientific experiments focused on understanding the planet’s climate history, surface geology, and potential for past or present life. Recently, the Mars Exploration Rover (MER) “Spirit” became deeply embedded in regolith at a site called Troy, ending its mission as a mobile science platform. The difficulty faced in navigating mobile robots over sloped, rocky, and deformable terrain has highlighted the importance of developing accurate simulation tools for use in a predictive mobility modeling capacity. These simulation tools require accurate knowledge of terrain model parameters. This paper describes a terramechanics-based tool for simulation of rover mobility. It also describes ongoing work toward estimation of terrain parameters of Mars soil.

Palaeoglaciation in the low latitude, low elevation tropical Andes, northern Peru

2021 ◽  
Author(s):  
Ethan Lee ◽  
Neil Ross ◽  
Andrew Henderson ◽  
Andrew Russell ◽  
Stewart Jamieson ◽  
...  
Keyword(s):  
High Elevation ◽  
Tropical Andes ◽  
Low Latitude ◽  
Climate History ◽  
Ongoing Research ◽  
Important Region ◽  
Ongoing Work ◽  
Geomorphological Map ◽  
Northern Peru ◽  
Data Gap

<p>Palaeo-glaciological studies of former ice thickness and extent within the tropical Andes have tended to focus on locations where glaciers are currently present, or in high elevation locations where evidence exists of recently deglaciated cirques. Few studies have focussed on low elevation regions due to the presumption that glaciers could not have existed at such low altitudes within the tropics. A latitudinal ‘data gap’ exists between Ecuador and more central and southern Peru where evidence for former glaciation is abundant. To fill this gap we present rare evidence of past glaciation from the Las Huaringas region, northern Peru, located in a relatively low elevation massif (<3900 m).</p><p>Within Las Huaringas a large valley glacier existed, extending N-S ~12 km down valley to ~2900 m in elevation while glacial cirques existed exhibiting an E-W orientation on the western facing hillslope of the massif with pronounced moraine complexes and bedrock erosion. We used high-resolution remotely sensed imagery, a 30 m ALOS DEM, and preliminary field observations to identify and map an abundance of geomorphic evidence of glaciation. These include moraines at different stages of preservation and predominance, eroded bedrock surfaces, cirque landforms and overdeepened valleys to develop the first glacial geomorphological map of the region. We performed morphometric analysis (e.g. width, length, altitude, azimuth) of the mapped glacial landforms and cirques along with hypsometric analysis of the main valley of Laguna Shimbe, yielding a hypsometric maxima of 3250 m. Using the geomorphological map, we determine the former extent and thickness of palaeoglaciers in the area and use delineated glacial outlines of their furthest extent to reconstruct Equilibrium Line Altitudes (ELAs) of these ice masses using a combination of ELA estimation techniques.</p><p>Ongoing research aims to determine whether the palaeoglacial evidence is consistent with formation by valley glaciers or an icecap and whether the timing of the local Last Glacial Maximum (LGM) was synchronous with the global timing. A set of hypotheses for the timing and drivers of the reconstructed extent of former glaciers in the area will be presented. Our analysis confirms the presence of former glaciers in a low elevation and low latitude region of the tropical Andes. Our ongoing work aims to unveil the timing of the glacial events and the drivers of the glacial and climate history seen within this important region.</p>

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

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

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

scholarly journals JMASM 51: Bayesian Reliability Analysis of Binomial Model – Application to Success/Failure Data

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
M. Tanwir Akhtar ◽  
Athar Ali Khan
Keyword(s):  
Bayesian Model ◽  
Real Data ◽  
Model Parameters ◽  
Data Sets ◽  
Binomial Model ◽  
Model Application ◽  
Simulation Tools ◽  
Failure Data ◽  
Simulation Techniques ◽  
Bayesian Paradigm

Reliability data are generated in the form of success/failure. An attempt was made to model such type of data using binomial distribution in the Bayesian paradigm. For fitting the Bayesian model both analytic and simulation techniques are used. Laplace approximation was implemented for approximating posterior densities of the model parameters. Parallel simulation tools were implemented with an extensive use of R and JAGS. R and JAGS code are developed and provided. Real data sets are used for the purpose of illustration.

scholarly journals Snow-Avalanche Maps for use by the Norwegian Army

1989 ◽  
Vol 13 ◽  
pp. 170-174 ◽  
Author(s):  
K. Lied ◽  
F. Sandersen ◽  
R. Toppe
Keyword(s):  
Large Scale ◽  
Work Station ◽  
Northern Norway ◽  
Digital Maps ◽  
Interactive Graphic ◽  
Terrain Model ◽  
Military Exercises ◽  
Terrain Parameters ◽  
Graphic Work ◽  
Usual Scale

Mapping of areas exposed to avalanche hazard for the Norwegian Army was started by the Norwegian Geotechnical Institute in 1986. The background to this mapping is that large-scale military exercises are held annually in northern Norway, in terrain where there is a high danger of avalanche activity. Avalanche areas are divided into two zones: potential starting zones, and potential run-out zones. All potential avalanche areas are indicated on maps, and mapping is carried out by computer using a terrain model and digital maps. An interactive graphic work station is used to outline danger areas. Starting and run-out zones are identified by using terrain parameters which may be extracted from digital maps. The usual scale of the avalanche maps is 1 : 50 000, with 20 m contour intervals.

scholarly journals CO<sub>2</sub> fluxes and ecosystem dynamics at five European treeless peatlands – merging data and process oriented modeling

2015 ◽  
Vol 12 (1) ◽  
pp. 125-146 ◽  
Author(s):  
C. Metzger ◽  
P.-E. Jansson ◽  
A. Lohila ◽  
M. Aurela ◽  
T. Eickenscheidt ◽  
...  
Keyword(s):  
Water Table ◽  
Photosynthetic Efficiency ◽  
Heterotrophic Respiration ◽  
Soil Conditions ◽  
Model Parameters ◽  
Co2 Fluxes ◽  
Site Specific ◽  
Process Oriented ◽  
A Site ◽  
Organic Decomposition

Abstract. The carbon dioxide (CO2) exchange of five different peatland systems across Europe with a wide gradient in land use intensity, water table depth, soil fertility and climate was simulated with the process oriented CoupModel. The aim of the study was to find out whether CO2 fluxes, measured at different sites, can be explained by common processes and parameters or to what extend a site specific configuration is needed. The model was calibrated to fit measured CO2 fluxes, soil temperature, snow depth and leaf area index (LAI) and resulting differences in model parameters were analyzed. Finding site independent model parameters would mean that differences in the measured fluxes could be explained solely by model input data: water table, meteorological data, management and soil inventory data. Seasonal variability in the major fluxes was well captured, when a site independent configuration was utilized for most of the parameters. Parameters that differed between sites included the rate of soil organic decomposition, photosynthetic efficiency, and regulation of the mobile carbon (C) pool from senescence to shooting in the next year. The largest difference between sites was the rate coefficient for heterotrophic respiration. Setting it to a common value would lead to underestimation of mean total respiration by a factor of 2.8 up to an overestimation by a factor of 4. Despite testing a wide range of different responses to soil water and temperature, rate coefficients for heterotrophic respiration were consistently the lowest on formerly drained sites and the highest on the managed sites. Substrate decomposability, pH and vegetation characteristics are possible explanations for the differences in decomposition rates. Specific parameter values for the timing of plant shooting and senescence, the photosynthesis response to temperature, litter fall and plant respiration rates, leaf morphology and allocation fractions of new assimilates, were not needed, even though the gradient in site latitude ranged from 48° N (southern Germany) to 68° N (northern Finland) differed largely in their vegetation. This was also true for common parameters defining the moisture and temperature response for decomposition, leading to the conclusion that a site specific interpretation of these processes is not necessary. In contrast, the rate of soil organic decomposition, photosynthetic efficiency, and the regulation of the mobile carbon pool need to be estimated from available information on specific soil conditions, vegetation and management of the ecosystems, to be able to describe CO2 fluxes under different conditions.

scholarly journals Modelling albedo and distributed snowmelt across a low hill in Svalbard

2005 ◽  
Vol 36 (3) ◽  
pp. 207-218 ◽  
Author(s):  
Richard Essery ◽  
Eleanor Blyth ◽  
Richard Harding ◽  
Colin Lloyd
Keyword(s):  
Land Surface ◽  
Land Surface Model ◽  
Surface Model ◽  
Model Parameters ◽  
Good Match ◽  
Composite Surface ◽  
Fractional Coverage ◽  
A Site ◽  
Single Set ◽  
Snow Mass

A land-surface model is used to simulate the albedo and mass of patchy snowcovers during radiation-driven melt for three years at a site in Svalbard. Performing single energy and mass balance calculations for the combined snow-covered and snow-free parts of the surface gives a faster decrease in albedo than observed because too much of the solar radiation absorbed by the composite surface is used to melt snow. Representing the snowcover separately allows the model to be calibrated to give a good match to the observed albedo for each of the years studied. A single set of model parameters cannot, however, give a good simulation for all of the years. The average snow mass and snowcover fraction measured on a grid of points can be simulated using either a distributed version of the model or a more efficient tiled version supplied with the observed relationship between snow mass and fractional coverage. Parameters obtained by optimising the snow mass simulations are more consistent from year to year than from the albedo simulations.

Summary Guide to Spanish Florida Missions and Visitas With Churches in the Sixteenth and Seventeenth Centuries

1990 ◽  
Vol 46 (4) ◽  
pp. 417-513 ◽  
Author(s):  
John H. Hann
Keyword(s):  
American Southwest ◽  
Native People ◽  
Ongoing Work ◽  
Spanish Missions ◽  
Spanish Florida ◽  
American Southeast ◽  
Comprehensive Listing ◽  
A Site ◽  
Recent Monograph ◽  
Tribal Affiliation

The early European presence in California and in the American Southwest in general is identified with missions. Although missions were equally important in Spanish Florida and at an earlier date, the average American does not associate missions with Florida or Georgia. Indeed, as David Hurst Thomas observed in a recent monograph on the archaeological exploration of a site of the Franciscan mission of Santa Catalina de Guale on Georgia's St. Catherines Island, the numerous missions of Spanish Florida have remained little known even in scholarly circles. And as Charles Hudson has noted, this ignorance or amnesia has extended to awareness of the native peoples who inhabited those Southeastern missions or were in contact with them, even though these aboriginal inhabitants of the Southeast “possessed the richest culture of any of the native people north of Mexico … by almost any measure.” Fortunately, as Thomas remarked in the above-mentioned monograph, “a new wave of interest in mission archaeology is sweeping the American Southeast.” This recent and ongoing work holds the promise of having a more lasting impact than its historical counterpart of a half-century or so ago in the work of Herbert E. Bolton, Fr. Maynard Geiger, OFM, Mary Ross, and John Tate Lanning. Over the fifty odd years since Lanning's Spanish Missions of Georgia appeared, historians and archaeologists have made significant contributions to knowledge about sites in Spanish Florida where missions or mission outstations and forts or European settlements were established. But to date no one has compiled a comprehensive listing from a historian's perspective of the mission sites among them to which one may turn for the total number of such establishments, their general location, time of foundation, length of occupation, moving, circumstances of their demise and the tribal affiliation of the natives whom they served. This catalog and its sketches attempt to meet that need.

An NGA-West2 Empirical Model for Estimating the Horizontal Spectral Values Generated by Shallow Crustal Earthquakes

2014 ◽  
Vol 30 (3) ◽  
pp. 1155-1177 ◽  
Author(s):  
I. M. Idriss
Keyword(s):  
Empirical Model ◽  
Site Response ◽  
Earthquake Ground Motion ◽  
Model Parameters ◽  
Motion Data ◽  
Crustal Earthquakes ◽  
Nonlinear Site Response ◽  
Average Shear ◽  
Recorded Data ◽  
A Site

An empirical model for estimating the horizontal pseudo-absolute spectral accelerations (PSA) generated by shallow crustal earthquakes was published in 2008 using the recorded earthquake ground motion data collected and documented as part of the original Next Generation Attenuation (NGA) project. A significant number of additional recordings were collected over the past three years, and the 2008 model has been revised using the new data and is presented in this paper. The model was again selected to be simple, and the model parameters were estimated using the expanded database. The revised model incorporates V S30 as an independent variable because, with the expanded database, it was found that V S30 was required to be included as an independent parameter to allow for a reasonably unbiased fit to the recorded data. It is noted that V S30 is not being used to account for nonlinear site response, but strictly to allow for a better fit to the data. These parameters are presented for sites with an average shear wave velocity in the upper 30 m, V S30, for sites with V S30 ≥ 450 m/s. Parameters for sites with V S30 < 450 m/s are not included in this paper. For a site with V S30 = 450 m/s, there is an overall increase in PGA averaging about 50% over a distance of about 100 km using the 2013 model in comparison to the 2008 model. On the other hand, for a site with V S30 = 900 m/s, there is an overall decrease of about 10% using the 2013 model in comparison to the 2008 model.

scholarly journals Virtual field experiences in a web-based videogame environment: Open-ended examples of existing and fictional field sites

2021 ◽  
Author(s):  
Mattathias D. Needle ◽  
Juliet G. Crider ◽  
Jacky Mooc ◽  
John F. Akers
Keyword(s):  
Three Dimensional ◽  
Field Experiences ◽  
Learning Goals ◽  
Geologic Mapping ◽  
Terrain Model ◽  
Virtual Field ◽  
Modeling Software ◽  
Game Environment ◽  
A Site ◽  
Space Sciences

Abstract. We present two original, videogame-style field-geology experiences designed to allow flexible, open-ended exploration for geologic mapping and structural geology. One simulation features the Whaleback anticline, a site in central Pennsylvania (USA) with three-dimensional exposure of a 30-m-high fold, based on a terrain model that was acquired through structure-from-motion photogrammetry. The second example is a fictional location with simplified geology, built with digital modeling software and inspired by the geology of northwestern Washington. Users move through the terrain, as if in the field, selecting where to make observations of the geologic structure. Additionally, these virtual field experiences provide novel visualization opportunities through tools like a geodetic compass that instantly plots data to a stereonet, and a jetpack simulation which allows the user to interrogate geologic surfaces in hard-to-reach locations. We designed the virtual field experiences in a widely-used videogame-creation software and published the field simulations for access via the internet and common web browsers, so that no special hardware or software is required to play. We implemented these field simulations to partially replace field and lab exercises in two different courses offered remotely through the University of Washington Department of Earth and Space Sciences, with assignments that address many of the learning goals of traditional in-person exercises. Because the virtual field experiences are open-ended, other instructors can design different exercises to meet different learning goals. While this game environment currently serves as an enhancement to remote education, this format can also augment traditional educational experiences, overcoming several challenges to accessing the field or particular outcrops and thereby broadening opportunities for participation and scientific collaboration.

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