Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references (p.86-89).

abstract: Human recreation on rangelands may negatively impact wildlife populations. Among those activities, off-road vehicle (ORV) recreation carries the potential for broad ecological consequences. A study was undertaken to assess the impacts of ORV on rodents in Arizona Uplands Sonoran Desert. Between the months of February and September 2010, rodents were trapped at 6 ORV and 6 non-ORV sites in Tonto National Forest, AZ. I hypothesized that rodent abundance and species richness are negatively affected by ORV use. Rodent abundances were estimated using capture-mark-recapture methodology. Species richness was not correlated with ORV use. Although abundance of Peromyscus eremicus and Neotoma albigula declined as ORV use increased, abundance of Dipodomys merriami increased. Abundance of Chaetodipus baileyi was not correlated with ORV use. Other factors measured were percent ground cover, percent shrub cover, and species-specific shrub cover percentages. Total shrub cover, Opuntia spp., and Parkinsonia microphylla each decreased as ORV use increased. Results suggest that ORV use negatively affects rodent habitats in Arizona Uplands Sonoran Desert, leading to declining abundance in some species. Management strategies should mitigate ORV related habitat destruction to protect vulnerable populations. / Dissertation/Thesis / M.S. Applied Biological Sciences 2012

Submitted by Dilene Paulo (dilene.fatima@ufcg.edu.br) on 2018-02-07T12:18:55Z No. of bitstreams: 1 DIEGO DAVID SILVA DINIZ – DISSERTAÇÃO PPGEM 2014.pdf: 4871335 bytes, checksum: cfbb94b91722df0a50916a777f1ec43e (MD5) / Made available in DSpace on 2018-02-07T12:18:55Z (GMT). No. of bitstreams: 1 DIEGO DAVID SILVA DINIZ – DISSERTAÇÃO PPGEM 2014.pdf: 4871335 bytes, checksum: cfbb94b91722df0a50916a777f1ec43e (MD5) Previous issue date: 2014-12-03 / CNPq / Atualmente, o desenvolvimento da indústria automotiva e uma maior exigência do mercado estimularam a intensificação dos estudos na dinâmica veicular, levando os fabricantes a focarem seus esforços em produzir e otimizar tecnologias capazes de obter veículos mais rápidos, seguros e confortáveis. Com a evolução da computação, tornou-se viável a realização de simulação numérica para modelos complexos de veículos que fosse capaz de otimizar e compreender o real comportamento dinâmico do veículo, submetidos às situações adversas. Dentro desse contexto, este trabalho visa apresentar um estudo de modelagem computacional (modelo quarter car, half car e multicorpos) aplicados para avaliação do comportamento dinâmico vertical de um veículo do tipo off-road (Baja) com suspensão dianteira e traseira do tipo duplo A. Para este fim, foram feitos levantamentos experimentais dos parâmetros de suspensão associados a estudos da dinâmica vertical de um veículo off-road, do tipo baja, com auxílio da máquina de ensaio dinâmica (MTS 321.21), além de estudos dinâmicos numa mesa inercial por meio de um analisador de vibrações. Mediante os parâmetros, foram construídos e simulados os modelos matemáticos, quarter car e half car no software MATLAB e o carro completo no ambiente multicorpos. Como resultados, foram avaliadas a influência da pressão interna dos pneus, a variação das rigidezes das molas e o efeito do amortecimento em situações comuns, que o veículo fora de estrada pode ser submetido, permitindo avaliar o seu comportamento dinâmico vertical. Assim, os perfis de pistas idealizadas nestes trabalhos foram: lombada, valas e swept sine. Nos experimentos, destaca-se a variação da rigidez radial dos pneus, quando ocorrem mudanças na sua pressão interna, o efeito da variação dos valores das massas não suspensa do sistema, modificando o comportamento dinâmico do veículo no momento de excitação pelas adversidades do solo, e a variação da força de contato pneu/solo com a mudança da pressão interna dos pneus. Ambos esses efeitos causam mudança no comportamento dinâmico vertical e, em alguns casos, até na dinâmica lateral, influenciando no desempenho do veículo, o que torna imprescindível realizar estes tipos de estudos para um melhor entendimento dos fenômenos existentes, durante situações que um veículo off road são submetidos. / Currently, the development of the automotive industry and greater market demand stimulated the intensification of studies on vehicular dynamics, leading manufacturers to centralize their efforts to produce and optimize technologies capable of faster, safer and comfortable vehicles. Through the evolution of computation, it became viable the realization of numerical simulation of complex models of vehicles that would be able to optimize and understand the real dynamic behavior of the vehicle subjected to adverse situations. Within this context, this paper presents a study of computational modeling (quarter car, half car and multibody models) used for assessment of the vertical dynamic behavior of a vehicle type off-road (Baja) with front and rear suspension Double A. To make it possible, surveys of experimental parameters associated with studies of suspension of a vehicle off-road, the baja type, with the aid of dynamic testing (MTS 321.21) vertical machine dynamics were made in addition to dynamic studies in one inertial table through a vibrations analyzer. Through parameters, mathematical models (quarter car and half car) were built and simulated in MATLAB software. The complete car were built and simulated in multibody environment. With the results, there were evaluated the influence of the internal tire pressure, the variation of springs stiffness and the dampening effect throughout ordinary situations to this kind of vehicle and then allowing evaluates its vertical dynamic behavior. Therefore, the profiles of these works were idealized clues: speed bump, ditches and swept sine. In the experiments stands out a variation of the radial stiffness of the tire, when changes occur in their internal pressure, the effect of varying the values of the unsprung mass of the system, modifying the dynamic behavior of the vehicle at the time of excitation by the adversities of the soil, and the variation of contact force tire / ground with the change of the internal pressure of the tires. These effects cause changes in the vertical dynamic behavior, and in some cases even in the lateral dynamics may influence the performance of the vehicle, which makes it essential to make these types of studies to better understand the phenomena existing in situations that are off-road vehicle submitted.

Die doel van die navorsing wat in hierdie verslag bespreek word, was om ondersoek in te stel na die omrolgedrag van veldvoertuie. Die studie is gedoen deur gebruik te maak van ʼn Land Rover Defender 110 sport nutsvoertuig as eksperimentele voertuig, en ADAMS View as sagteware pakket Die sogenaamde “vishoektoets” is met die basislynvoertuig uitgevoer. Daar is korrelasie verkry tussen die data wat tydens die toetse opgeneem is, en ʼn volledige drie-dimensionele model van die voertuig in ADAMS View. Die basislynsuspensie op die voertuig is vervolgens vervang met ʼn vier toestand semi-aktiewe hidropneumatiese suspensiestelsel of 4S4. Die toetse is herhaal, en korrelasie verkry tussen die toetsdata en die rekenaarmodel. Die rekenaarmodel, met die basislyn suspensiekarakteristieke vervang met die hidropneumatiese suspensiekarakteristieke, is teen hierdie toetsdata geverifieer. Die rekenaarmodel is na korrelasie gebruik om te bepaal watter veer- en demperstellings die effektiefste sal wees om omrol te voorkom. Verder is die model ook gebruik om die effek van rithoogteverlaging op omrolgeneigdheid te bepaal. Die hoeveelheid wat die wiele oplig, is as norm vir omrolgeneigdheid gebruik. Ander parameters, soos giersnelheid, rolsnelheid en rolhoek is ook ondersoek. Uit die studie is dit duidelik dat die 4S4, met die moontlikheid van verstelling aan rithoogte, sinvol aangewend kan word om omrolgeneigdheid te verminder. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2008. / Mechanical and Aeronautical Engineering / unrestricted

The designers of heavy, off-road vehicle suspension systems face unique challenges. The ride comfort versus handling compromise in these vehicles has been frequently investigated using mathematical optimisation. Further challenges exist due to the large variations in vehicle sprung mass. The suspension system must provide adequate isolation from road load inputs throughout its payload operating range. This is imperative if good vehicle structural life is to be ensured. A passive suspension system can only provide optimal isolation at a single payload. The designer of such a suspension system must therefore make a compromise between designing for a fully-laden or unladen payload state. This work deals with suspension optimisation for vehicle structural life. The work mainly addresses two questions: 1) What are the suspension characteristics required to ensure optimal isolation of the vehicle structure from road loads? and 2) If such optimal suspension characteristics can be found, how sensitive are they to changes in vehicle payload? The study aims to answer these questions by examining a Land Rover Defender 110 as case study. An experimentally validated mathematical model of the test vehicle is constructed for the use in sensitivity studies. Mathematical optimisation is performed using the model in order to find the suspension characteristics for optimal structural life of the vehicle under consideration. Sensitivity studies are conducted to determine the robustness of the optimal characteristics and their sensitivity to vehicle payload variation. Recommendations are made for suspension characteristic selection for optimal structural life. AFRIKAANS : Ontwerpers van swaar, veldvoertuig suspensie stelsels staar unieke uitdagings in die gesig. Die ritgemak teenoor hantering kompromie in hierdie voertuie is reeds telkemale ondersoek, ook met wiskundige optimering. Verdere uitdagings bestaan as gevolg van die groot veranderinge in geveerde massa by hierdie voertuie. Die suspensiestelsel moet gepaste isolasie van pad insette oor `n wye reeks van bedryfstoestande lewer. Dit is veral belangrik indien daar verseker wil word dat die voertuig goeie struktuurleeftyd het. `n Passiewe suspensiestelsel kan egter slegs optimale isolasie by `n enkele vragtoestand lewer. Die ontwerper van `n passiewe suspensie stelsel moet dus `n kompromie aangaan tussen ontwerp vir `n vol of leë vragtoestand. Hierdie studie handel oor suspensie optimering vir struktuur leeftyd. Die werk spreek hoofsaaklik twee vraagstukke aan: 1) Watter suspensie karakteristieke word benodig om die voertuig struktuur optimaal van padinsette te isoleer? en 2) Indien sulke optimale karakteristieke gevind kan word, wat is hulle sensitiwiteit vir veranderinge in voertuig vrag? Die studie mik om hierdie vraagstukke aan te spreek deur ondersoeke op `n Land Rover Defender 110 toetsvoertuig. `n Eksperimenteel gevalideerde, wiskundige model van die toetsvoertuig word saamgestel met die oog op sensitiwiteitstudies. Wiskundige optimering word met die model uitgevoer om sodoende die suspensie karakteristieke vir optimale struktuurleeftyd vir die betrokke toetsvoertuig te bepaal. Sensitiwiteitsanalises word gedoen om die robuustheid van die optimale karakteristieke, met betrekking tot veranderinge in voertuig vrag, vas te stel. Aanbevelings word gemaak oor die keuse van suspensie karakteristieke vir optimale struktuur leeftyd. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

A ground vehicle is a dynamic system containing many non-linear components, ranging from the non-linear engine response to the tyre-road interface. In pursuit of developing driver-assist systems for accident avoidance, as well as fully autonomous vehicles, the application of modern mechatronics systems to vehicles are widely investigated. Extensive work has been done in an attempt to model and control the lateral response of the vehicle system utilising a wide variety of conventional control and intelligent systems theory. The majority of driver models are however intended for low speed applications where the vehicle dynamics are fairly linear. This study proposes the use of adaptive control strategies as robust driver models capable of steering the vehicle without explicit knowledge of vehicle parameters. A Model Predictive Controller (MPC), self-tuning regulator and Linear Quadratic Self-Tuning Regulator (LQSTR) updated through the use of an Auto Regression with eXogenous input (ARX) model that describes the relation between the vehicle steering angle and yaw rate are considered as solutions. The strategies are evaluated by performing a double lane change in simulation using a validated full vehicle model in MSC ADAMS and comparing the maximum stable speed and lateral offset from the required path. It is found that all the adaptive controllers are able to successfully steer the vehicle through the manoeuvre with no prior knowledge of the vehicle parameters. An LQSTR proves to be the best adaptive strategy for driver model applications, delivering a stable response well into the non-linear tyre force regime. This controller is implemented on a fully instrumented Land Rover 110 of the Vehicle Dynamics Group at the University of Pretoria fitted with a semi-active spring-damper suspension that can be switched between two discrete setting representing opposite extremes of the desired response namely: ride mode (soft spring and low damping) and handling mode (stiff spring and high damping). The controller yields a stable response through a severe double lane change (DLC) up to the handling limit of the vehicle, safely completing the DLC at a maximum speed of 90 km/h all suspension configurations. The LQSTR also proves to be robust by following the same path for all suspension configurations through the manoeuvre for vehicle speeds up to 75 km/h. Validation is continued by successfully navigating the Gerotek dynamic handling track, as well as by performing a DLC manoeuvre on an off-road terrain. The study successfully developed and validated a driver model that is robust against variations in vehicle parameters and friction coefficients. / Dissertation (MEng)--University of Pretoria, 2015. / Mechanical and Aeronautical Engineering / Unrestricted

This study focuses on developing a better comprehension of the mobility of lightweight autonomous vehicles with varying locomotion platforms on sand. This research involves four segments. The first segment is a review of military criteria for the development of lightweight unmanned ground vehicles, followed by a review a review of current methodologies for evaluating the terramechanic (vehicle-ground interaction) mobility measures of heavyweight wheeled and tracked vehicles, and ending with a review of the defining properties of deformable terrain with specific emphasis on sand. These present a basis for understanding what currently defines mobility and how mobility is quantified for traditional heavyweight wheeled and tracked vehicles, as well as an understanding of the environment of operation (sandy terrain) for the lightweight vehicles in this study. The second segment involves the identification of key properties associated with the mobility and operation of lightweight vehicles on sand as related to given mission criteria, so as to form a quantitative assessment system to compare lightweight vehicles of varying locomotion platforms. A table based on the House of Quality shows the relationships—high, low, or adverse—between mission profile requirements and general performance measures and geometries of vehicles under consideration for use. This table, when combined with known values for vehicle metrics, provides information for an index formula used to quantitatively compare the mobility of a user-chosen set of vehicles, regardless of their methods of locomotion. This table identifies several important or fundamental terramechanics properties that necessitate model development for robots with novel locomotion platforms and testing for lightweight wheeled and tracked vehicles so as to consider the adaptation of counterpart heavyweight terramechanics models for use. The third segment is a study of robots utilizing novel forms of locomotion, emphasizing the kinematics of locomotion (gait and foot placement) and proposed starting points for the development of terramechanics models so as to compare their mobility and performance with more traditional wheeled and tracked vehicles. In this study several new autonomous vehicles—bipedal, self-excited dynamic tripedal, active spoke-wheel—that are currently under development are explored. The final segment involves experimentation of several lightweight vehicles and robots on sand. A preliminary experimentation was performed evaluating a lightweight autonomous tracked vehicle for its performance and operation on sand. A bipedal robot was then tested to study the foot-ground interaction with and sinkage into a medium-grade sand, utilizing a one of the first-developed walking gaits. Finally, a comprehensive set of experiments was performed on a lightweight wheeled vehicle. While the terramechanics properties of wheeled and tracked vehicles, such as the contact patch pressure distribution, have been understood and models have been developed for heavy vehicles, the feasibility of extrapolating them to the analysis of light vehicles is still under analysis. A wheeled all-terrain vehicle was tested for effects of sand gradation, vehicle speed, and vehicle payload on measures of pressure and sinkage in the contact patch, and preliminary analysis is presented on the sinkage of the wheeled all-terrain vehicle. These four segments—review of properties of sandy terrain and measures of and criteria for the mobility of lightweight vehicles operating on sandy terrain, the development of the comparison matrix and indexing function, modeling and development of novel forms of locomotion, and physical experimentation of lightweight tracked and wheeled vehicles as well as a bipedal robot—combine to give an overall picture of mobility that spans across different forms of locomotion. / Master of Science

The purpose of this thsis is to develop a vision perception based Intelligent Vehicle Driving Assistant System ( IVDAS ), which utilizes CCD camera to capture the movement of vehicle and road image on DSP-Based . According to daytime and night time, we analyzed the full information in the image to acquire the important and proper characteristics about lane mark and vehicle. There are two sub-systems in our system , including Lane Mark Detection and Vehicle Detection. The main goal is to identify if there are existing vehicles in the front of or near our vehicle. This system can provide information for the Intelligent Vehicle to make decision to avoid accident happening and assisted driver in driving safely.

<p>The purpose of this project is to get a fully functional, automatic steering system and a variable breaking system with an emergency breaking function to an off road vehicle. This off road vehicle is supposed to work as an aid in military situations. A team of two, Sebastian Attervall and Nichlas Gustafsson, got an order from Jonas Nyårds and the PreeRunners Project to construct a steering system that could manoeuvre an off road vehicle without any human involvement. To make this possible the vehicle would be guided by onboard sensors, cameras and computers. The team where also assigned to construct an automatic breaking system, there also no human would be involved. The breaking system should as well contain an emergency stop function to prevent any accidents. The team has solved the problems assigned by using theories by David G. Ullman. The system that was eventually chosen was a steering system containing a 48V, 250W DC motor. A planetary gear where chosen to increase the torque from the engine. To translate the torque from the planetary gear to the steering bar a chain with chainwheel where chosen, this because the chain and chainwheel could withstand the immense forces acting on the chain. Between the planetary gear and the chainwheel a skid clutch is placed to prevent destruction on the planetary gear due to overload. The whole steering system is monitored by two rotary encoders, one placed on the engine and one placed on the steering bar. The breaking system eventually chosen where a system build on the existing drum brakes, placed in the front. To make the system independent from any human interference a system containing a linear motor, an electromagnet and a spring where chosen. The system works by letting the spring act on the wire from the existing drum breaks. The spring is always compressed so a force will always act on the wire when the system is at rest. By compressing the spring further the force acting on the wire will decrease and by compressing it enough the breaks will be released. The force compressing the spring will come from the linear motor. And to make the system failsafe in case of an emergency an electromagnet will be placed between the linear motor and the spring. When the power is cut to the electromagnet the compressed spring will be released and the drum breaks will break. The breaking system as well will be supervised by encoders and in this case linear encoders.</p> / <p>Syftet med detta projekt är att få ett fungerande automatiskt styrsystem och en variabel broms med nödbromsfunktion till en fyrhjuling som ska bli ett hjälpmedel i militära situationer. En projektgrupp bestående av Sebastian Attervall och Nichlas Gustafsson fick i uppgift av beställare Jonas Nygårds att ta fram ett system som ska kunna manövrera en fyrhjuling utan att en människa är inblandad. På detta vis ska den fungera helt automatiskt med hjälp av sensorer, kameror och datorer. Projektgruppen fick även i uppgift att ta fram en broms som ska kunna fungera utan inblandning av en människa. Den ska även kunna fungera som en nödbroms om systemet skulle strejka. Projektgruppen har löst de uppgifter som de har blivit tilldelade med hjälp av David G. Ullmans konstruktionsmetodik. Det system som tillslut valdes åt styrenheten blev ett system där momentet som vrider styrstången skapas med hjälp av en DC motor på 48 V och 250 W. Efter motorn sätts en planetväxel för att öka momentet. Som överföring av momentet från planetväxeln till styrstången används kedjedrift, detta på grund av att kedjan klarar av att ta upp de krafter som uppstår. En slirkoppling finns även med mellan planetväxeln och kedjedriften för att inte motorn och planetväxeln ska ta stryk vid överbelastning. Hela detta system övervakas med rotationsgivare vid motorn och styrstången så att inget fel uppstår. Konstruktionen för bromsen blev tillslut en lösning där de befintliga trumbromsarna på framhjulen används. För att bromsen ska kunna fungera utan inblandning av en människa har projektgruppen valt ett system bestående av ett linjärt ställdon, en elektromagnet och en fjäder. Systemet fungerar på så sätt att fjädern trycks ihop och en kraft uppstår. Denna kraft kommer att spänna bromsvajern så trumbromsen låser sig. Men för att inte trumbromsen ska ligga i hela tiden valde projektgruppen att använda sig av ett ställdon för att trycka ihop fjädern ytterligare så att vajern slaknar och bromskraften försvinner. För att nödbromsfunktionen ska fungera sattes en elektromagnet mellan ställdonet och fjädern. Om fyrhjulingen skulle bli strömlös släpper elektromagneten och fjädern drar åt bromsvajern. Även detta system kommer att övervakas av givare och i detta fall av en linjärgivare.</p>

The purpose of this project is to get a fully functional, automatic steering system and a variable breaking system with an emergency breaking function to an off road vehicle. This off road vehicle is supposed to work as an aid in military situations. A team of two, Sebastian Attervall and Nichlas Gustafsson, got an order from Jonas Nyårds and the PreeRunners Project to construct a steering system that could manoeuvre an off road vehicle without any human involvement. To make this possible the vehicle would be guided by onboard sensors, cameras and computers. The team where also assigned to construct an automatic breaking system, there also no human would be involved. The breaking system should as well contain an emergency stop function to prevent any accidents. The team has solved the problems assigned by using theories by David G. Ullman. The system that was eventually chosen was a steering system containing a 48V, 250W DC motor. A planetary gear where chosen to increase the torque from the engine. To translate the torque from the planetary gear to the steering bar a chain with chainwheel where chosen, this because the chain and chainwheel could withstand the immense forces acting on the chain. Between the planetary gear and the chainwheel a skid clutch is placed to prevent destruction on the planetary gear due to overload. The whole steering system is monitored by two rotary encoders, one placed on the engine and one placed on the steering bar. The breaking system eventually chosen where a system build on the existing drum brakes, placed in the front. To make the system independent from any human interference a system containing a linear motor, an electromagnet and a spring where chosen. The system works by letting the spring act on the wire from the existing drum breaks. The spring is always compressed so a force will always act on the wire when the system is at rest. By compressing the spring further the force acting on the wire will decrease and by compressing it enough the breaks will be released. The force compressing the spring will come from the linear motor. And to make the system failsafe in case of an emergency an electromagnet will be placed between the linear motor and the spring. When the power is cut to the electromagnet the compressed spring will be released and the drum breaks will break. The breaking system as well will be supervised by encoders and in this case linear encoders. / Syftet med detta projekt är att få ett fungerande automatiskt styrsystem och en variabel broms med nödbromsfunktion till en fyrhjuling som ska bli ett hjälpmedel i militära situationer. En projektgrupp bestående av Sebastian Attervall och Nichlas Gustafsson fick i uppgift av beställare Jonas Nygårds att ta fram ett system som ska kunna manövrera en fyrhjuling utan att en människa är inblandad. På detta vis ska den fungera helt automatiskt med hjälp av sensorer, kameror och datorer. Projektgruppen fick även i uppgift att ta fram en broms som ska kunna fungera utan inblandning av en människa. Den ska även kunna fungera som en nödbroms om systemet skulle strejka. Projektgruppen har löst de uppgifter som de har blivit tilldelade med hjälp av David G. Ullmans konstruktionsmetodik. Det system som tillslut valdes åt styrenheten blev ett system där momentet som vrider styrstången skapas med hjälp av en DC motor på 48 V och 250 W. Efter motorn sätts en planetväxel för att öka momentet. Som överföring av momentet från planetväxeln till styrstången används kedjedrift, detta på grund av att kedjan klarar av att ta upp de krafter som uppstår. En slirkoppling finns även med mellan planetväxeln och kedjedriften för att inte motorn och planetväxeln ska ta stryk vid överbelastning. Hela detta system övervakas med rotationsgivare vid motorn och styrstången så att inget fel uppstår. Konstruktionen för bromsen blev tillslut en lösning där de befintliga trumbromsarna på framhjulen används. För att bromsen ska kunna fungera utan inblandning av en människa har projektgruppen valt ett system bestående av ett linjärt ställdon, en elektromagnet och en fjäder. Systemet fungerar på så sätt att fjädern trycks ihop och en kraft uppstår. Denna kraft kommer att spänna bromsvajern så trumbromsen låser sig. Men för att inte trumbromsen ska ligga i hela tiden valde projektgruppen att använda sig av ett ställdon för att trycka ihop fjädern ytterligare så att vajern slaknar och bromskraften försvinner. För att nödbromsfunktionen ska fungera sattes en elektromagnet mellan ställdonet och fjädern. Om fyrhjulingen skulle bli strömlös släpper elektromagneten och fjädern drar åt bromsvajern. Även detta system kommer att övervakas av givare och i detta fall av en linjärgivare.