A common problem encountered in mobile hydraulics is the desire to automate motion control functions in a restricted-cost and restricted-sensor environment. In this thesis a solution to this problem is presented. A velocity control scheme based on a novel single component pressure compensated ow controller was developed and evaluated. <p> The development of the controller involved solving several distinct technical challenges. First, a model reference control scheme was developed to provide control of the valve spool displacement for a particular electrohydraulic proportional valve. The control scheme had the effect of desensitizing the transient behaviour of the valve dynamics to changes in operating condition. Next, the pressure/flow relationship of the same valve was examined. A general approach for the mathematical characterization of this relationship was developed. This method was based on a modification of the so-called turbulent orifice equation. The general approach included a self-tuning algorithm. Next, the modified turbulent orifice equation was applied in conjunction with the model reference valve controller to create a single component pressure compensated flow control device. This required an inverse solution to the modified orifice equation. Finally, the kinematics of a specific single link hydraulically actuated mechanism were solved. Integration of the kinematic solution with the flow control device allowed for predictive velocity control of the single link mechanism.

A common problem encountered in mobile hydraulics is the desire to automate motion control functions in a restricted-cost and restricted-sensor environment. In this thesis a solution to this problem is presented. A velocity control scheme based on a novel single component pressure compensated ow controller was developed and evaluated. <p> The development of the controller involved solving several distinct technical challenges. First, a model reference control scheme was developed to provide control of the valve spool displacement for a particular electrohydraulic proportional valve. The control scheme had the effect of desensitizing the transient behaviour of the valve dynamics to changes in operating condition. Next, the pressure/flow relationship of the same valve was examined. A general approach for the mathematical characterization of this relationship was developed. This method was based on a modification of the so-called turbulent orifice equation. The general approach included a self-tuning algorithm. Next, the modified turbulent orifice equation was applied in conjunction with the model reference valve controller to create a single component pressure compensated flow control device. This required an inverse solution to the modified orifice equation. Finally, the kinematics of a specific single link hydraulically actuated mechanism were solved. Integration of the kinematic solution with the flow control device allowed for predictive velocity control of the single link mechanism.

Fuel cost represents a significant operating expense for owners and fleet managers of hydraulic off-highway vehicles. Further, the upcoming Tier IV compliance for off-highway applications will create further expense for after-treatment and cooling. Solutions that help address these factors motivate fleet operators to consider and pursue more fuelefficient hydraulic energy recovery systems. Electrical hybridization schemes are typically complex, expensive, and often do not satisfy customer payback expectations. This paper presents a hydraulic energy recovery architecture to realize energy recovery and utilization through a hydraulic hydro-mechanical transformer. The proposed system can significantly reduce hydraulic metering losses and recover energy from multiple services. The transformer enables recovered energy to be stored in a high-pressure accumulator, maximizing energy density. It can also provide system power management, potentially allowing for engine downsizing. A hydraulic test stand is used in the development of the transformer system. The test stand is easily adaptable to simulate transformer operations on an excavator by enabling selected mode valves. The transformer’s basic operations include shaft speed control, pressure transformation control, and output flow control. This paper presents the test results of the transformer’s basic operations on the test stand, which will enable a transformer’s full function on an excavator.

Off-Highway Vehicle (OHV) use has grown enormously on Utah’s public lands and is one of the most contentious and difficult issues for federal, state, and local land management agencies to address and provide for. Despite OHV use’s meteoric rise in popularity and its ongoing public conflicts, little is known about OHV recreationists. This thesis develops a typology that identifies within-activity differences related to recreation specialization; it also determines differences in OHV owners’ environmental attitudes and motivations. Findings show Utah’s owners comprise a range of use along the recreation specialization continuum. Results also indicate that an OHV owners’ specialization level is not a significant determinant of either their environmental attitude or four out of the seven given motivations for participation in the activity. Specialization is, however, directly correlated to three specific motivation domains: achievement/stimulation, independence, and meeting new people. Overall, the recreation specialization framework, broadly interpreted, was successfully utilized to develop a typology of use which can inform resource management decisions.

Fuel cost represents a significant operating expense for owners and fleet managers of hydraulic off-highway vehicles. Further, the upcoming Tier IV compliance for off-highway applications will create further expense for after-treatment and cooling. Solutions that help address these factors motivate fleet operators to consider and pursue more fuelefficient hydraulic energy recovery systems. Electrical hybridization schemes are typically complex, expensive, and often do not satisfy customer payback expectations. This paper presents a hydraulic energy recovery architecture to realize energy recovery and utilization through a hydraulic hydro-mechanical transformer. The proposed system can significantly reduce hydraulic metering losses and recover energy from multiple services. The transformer enables recovered energy to be stored in a high-pressure accumulator, maximizing energy density. It can also provide system power management, potentially allowing for engine downsizing. A hydraulic test stand is used in the development of the transformer system. The test stand is easily adaptable to simulate transformer operations on an excavator by enabling selected mode valves. The transformer’s basic operations include shaft speed control, pressure transformation control, and output flow control. This paper presents the test results of the transformer’s basic operations on the test stand, which will enable a transformer’s full function on an excavator.

This thesis presents two simulations of a heavy hybrid vehicle, the first part of the thesis is focused on the specifications of the vehicle designed in accordance with the requirements based on the literature study of the soils where the vehicle will travel. The second part presents the study of the vehicle through two simulations. The first simulation is oriented on the dynamical behavior of the vehicle. The second simulation focuses on the energy management of the vehicle. The presented thesis is a multi-disciplinary study, combining knowledge on vehicle dynamics, hydraulic suspensions and hybrid systems. The dynamical simulation of the vehicle has been performed with Matlab/Simulink and the third party program Delft-Tire for the tire modelling. Specials features of Matlab have been used; SimMechanics for the modelling of the parts, links and joints of the vehicle, and SimHydraulics for the modelling of the hydraulic suspensions. The principal tests performed on the vehicle by the dynamical simulation are the tests defined by the NATO - STANAG standards as AVTP 03-170. The tests are a crossing obstacle test and different sine wave roads. The obstacle of the obstacle crossing test is an APG-10 obstacle, an 10 inch high step with vertical edges. The objective of this simulation is to verify the design of the suspension and to observe the forces created in each link of the suspension system in order to design the chassis and the suspension system. The sine wave driving tests are performed to highlight the influence of the different hydraulic connections. Finally the slalom test presents the influence of the hydraulic anti-roll bar. The results show that the vehicle suspension verifies the STANAG standard. The results show also that the forces applied at the wheel by the obstacle crossing defined in the AVTP 03- 170 are directly related to the diameter and the stiffness of the tire. The maximum forces encountered at the wheel corresponds to 2.5 G vertically and 1.5 G longitudinally. The sine wave driving and the slalom test are showing the benefits and the need for advanced hydraulic suspensions. The second simulation is the modelling of the hybrid power management of the vehicle. The simulation has been performed with the objectives to create a tool for sizing series hybrid powertrain. This simulation has also been performed with Matlab/Simulink and the Simscape Library. The tool created show that when, the vehicle is equipped with 150 kW of power generation and 300 kW of battery would be able to drive at a constant speed of 10 km/h with the terrain inputs evaluated from the literature study, but to create sufficient result the input parameters of the tools need to have a better definition.

<p dir="ltr">In recent years increasingly stringent regulations regarding the pollution emissions and greenhouse gasses (GHG) of off-highway vehicles have emerged. However, recent studies underscores that off-highway vehicles have an average efficiency of 30%. In response, researchers are exploring the possibility of electrifying these vehicles with electric machines (EMs) potentially undertaking one, multiple, or all the vehicular functions previously reliant on internal combustion engines (ICEs).</p><p dir="ltr">Contemporary off-highway vehicle technology revolves around hydraulic systems tailored for diesel engines, tuned to specific torque characteristics and operating at a single speed. While replacing the prime mover with electric machines, the proper hydraulic supply capable of matching the same torque speed characteristics must be found. Furthermore, it must be determined whether an integration capable of reducing the mass, cost, and volume can be implemented, and if energy recuperation is possible. </p><p dir="ltr">In essence, achieving the desired transformation in off-highway vehicle technology necessitates a comprehensive reevaluation of both hydraulic systems and power sources, with electrification emerging as a promising strategy for harmonizing efficiency, emission standards, and performance expectations. </p><p><br></p><p dir="ltr">This work proposes guidelines to systematically design EMs and positive displacement hydraulic gear machines (HMs), along with their integration in an electro-hydraulic unit (EHU). To do so, three different variants of EHU are produced. The first variant features an external gear machine (EGM) integrated in a permanent magnet synchronous electric machine (PMSEM). The second and third variants integrate an internal gear machine (IGM) and a PMSEM, wherein the final variant introduces features endowing its operation at high rotational velocities.</p><p dir="ltr">The EM and HM constituting all variants of EHU are designed using a genetic algorithm-based optimization framework. This optimization framework encapsulates dedicated models for the EM and the HM that allow the calculation of the EHU performance. The first optimization objectives are the minimization of power consumption over the duty cycle of the selected reference machine, the minimization of the pressure and flow ripple, and maximization of the power density of the EHU. The optimization of the second and third variants instead only aims to maximize the total efficiency and power density of the EHU. </p><p dir="ltr">After having determined the parameters of the EHU through the optimization procedure the designs are refined with thorough simulations focusing on the fluid-dynamic features and the design of the axial balance system of the HMs. </p><p dir="ltr">The three variants present an increasing level of HM and EM integration and component reduction. While in the first variant HM and EM have a dedicated housing, and the HM is only positioned in the inert region of the EM, in the latest variants the HM and the EM also share the same casing. The first variant of EHU is air cooled by a radial fan system attached to the EM rotor and openings machined in the casing. The second variant takes advantage of the extreme integration and the differential pressure generated across the HM to liquid cooling the EM. The third variant necessitates the use of an external system to cool the EM. </p><p dir="ltr">To prove the effectiveness of the design process the first two EHU variants are prototyped and tested. The first EHU variant is tested both in a standalone configuration and on the reference machine showing total efficiency values up to 69%, proving its functionality and proving the capability of recuperating energy. The tests conducted on the second variant EHU show a volumetric efficiency that ranges between 81% and above 96% for a pinion rotation velocity of 6000 rpm proving the value of the presented design process. Despite the good quality of the volumetric efficiency values, this EHU variant present morphological limitations that negatively impact its mechanical efficiency. Finally, the third EHU concept is presented not only to remedy the morphological limitations of the second variant but also to address the challenges raised by high rotational velocity operation. </p>

abstract: Use of off-highway vehicles (OHV) in natural landscapes is a popular outdoor activity around the world. Rapid-growing OHV activity causes impacts on vegetation and land cover within these landscapes and can be an important factor in land degradation and ecosystem change. The Algodones Dunes in southeastern California is one of the largest inland sand dune complexes in the United States and hosts many endangered species. This study examines changes in land cover and OHV activity within two OHV active sites in comparison to an adjoined protected area. The study also investigates potential associations between land cover changes, climate trends, and OHV activity over recent decades. Time-series analysis was used to investigate the spatial-temporal changes and trends in the land cover in the Algodones Dunes from 2001 to 2016. In addition, high-resolution aerial photographs were analyzed to determine spatial patterns of OHV usage in comparison to visitor estimation collected by the Bureau of Land Management and observed changes in land cover composition between the control site and OHVs areas. A decreasing trend in Normalized Difference Vegetation Index over time indicates a decline in the amount of vegetation cover, which corresponds with an increasing trend in albedo and land surface temperature. Results also show a substantial difference in land cover between the control site and OHVs areas, which typically have a lower amount of vegetation cover, higher exposed sand surface, and increased anthropogenic features. Both climatic variations and OHV activity are statistically associated with land cover change in the dune field, although distinct causal mechanisms for the observed declines in vegetation cover could not be separated. The persistence of drought could inhibit vegetation growth and germination that, in turn, would hinder vegetation recovery in OHV areas. Meanwhile, repeated OHV driving has direct physical impacts on vegetation and landscape morphology, such as canopy destruction, root exposure, and increased aeolian sand transport. Active ecosystem protection and restoration is recommended to mitigate the response of declining vegetation cover and habitat loss to the impacts of OHV activity and climatic variability and allow natural recovery of re-establishement of nebkha dune ecosystems in the Algodones Dunes. / Dissertation/Thesis / Masters Thesis Geography 2018

Off-highway vehicle, such as excavators and forklifts, are heavy machines that are capable of causing harm to humans or damage property. Therefore, it is necessary to be able to develop interfaces for these kind of vehicles that can aid the operator to maintain a high level of situational awareness. How the interface affects the operators’ situational awareness is consequently an important metric to measure when evaluating the interface. Mixed reality simulators can be used to both develop and evaluate such interfaces in an immersive and safe environment. In this thesis we investigated how to measure situational awareness in a mixed-reality off-highway vehicle simulation scenario, without having to pause the scenario, by cross-referencing logs from the virtual environment and logs from the users' gaze position. Our method for investigating this research question was to perform a literature study and a user test. Each participant in the user test filled out a SART post-simulation questionnaire which we then compared with our measurement system.

In recent years increasing growth rate of all industrial fields generated an emerging energy demand and consequent environmental problems worldwide. Defining environmental profiles of products and systems using environmental tools, such as Life Cycle Assessment (LCA), is a critical issue for sustainable mining. In order to tackle the increasing environmental challenges and air emissions induced by surface coal mining, alternative material handling options are needed to be evaluated. This research study aims to provide a robust LCA model in selection of the alternative material haulage systems as a decision support system. The main objectives of this thesis study are: i) contributing to the national archived data by gathering data about haulage systems from an open pit coal mine, ii) constructing life cycle inventory from the acquired environmental data, iii) performing life cycle assessment of both material haulage systems in an open pit coal mine according to their environmental burdens, iv) conducting uncertainty assessment, and v) suggesting improvement in stages where emissions are critical. In order to accomplish these objectives, comparative LCA from cradle-to-grave was carried out in SIMAPRO 7.3 to determine life cycle environmental impacts of off-highway mining trucks and belt conveyors in coal transportation. Climate change and acidification were selected as major impact categories considered to be major concerns in mining industry. The results of this study revealed that off-highway trucks had 1.9 times greater impact on acidification category than belt conveyors, on the other hand, belt conveyors had 1.6 times greater impact on climate change. NOx emissions caused 96 percent of the acidification impact. CO2 emissions from fossil fuel combustion led to 95 percent of the climate change effect. The obtained results also indicated that the highest impact on all selected impact categories were generated from the utilization stage of the trucks operated by diesel oil and utilization of belt conveyor systems operated by electricity. The main novelty of this study is that it is one of the first LCA studies in the Turkish mining industry where considerable amount of emissions occur due to material handling. This study also advances the current knowledge about environmentally critical processes in material handling systems and places recommendations for both alternatives aiming better decision making. The results of the study are expected to provide a decision support system for the mining industry.