No description available.

The aim of my diploma thesis was engineering design of 4x4 chassis dynamometer model at 1:10 scale for presentation purpose and for testing RC cars models. The first part describes the current types of chassis dynamometers. The main goal of the thesis was designed the model itself in order to produce some parts of the dynamometer using 3D printing. The work also includes production drawings of individual parts and economic estimate of the entire production.

No description available.

No description available.

An energy management strategy for a prototype P4 parallel hybrid Chevrolet Blazer is developed for the EcoCAR Mobility Challenge. The objective of the energy management strategy is to reduce energy consumption while maintaining the drive quality targets of a conventional vehicle. A comprehensive model of the hybrid powertrain and vehicle physics is constructed to aid in the development of the control strategy. To improve fuel efficiency, a Willans line model is developed for the conventional powertrain and used to develop a rule-based torque split strategy. The strategy maximizes high efficiency engine operation while reducing round trip losses. Calibratable parameters for the torque split operating regions allow for battery state of charge management. Torque request and filtering algorithms are also developed to ensure the hybrid powertrain can smoothly and reliably meet driver demand. Vehicle testing validates that the hybrid powertrain meets acceleration response targets while delivering an enjoyable driving experience. Simulation testing shows that the energy management strategy improved fuel economy in most drive cycles with improvements of 8.8% for US06, 9.8% for HWFET, and 0.1% for the EcoCAR Mobility Challenge Cycle. Battery state of charge management behavior is robust across a variety of drive cycles using inputs from both simulated and test drivers. The resulting energy management strategy delivers an efficient, responsive, and reliable hybrid electric vehicle. / Master of Science / A control strategy for a hybrid vehicle is developed to improve fuel efficiency without sacrificing vehicle responsiveness. Efficiency improvements are achieved by the strategy intelligently selecting to use the engine, motor, or a combination of the two to minimize fuel consumption. The strategy also handles the important tasks of maintaining the battery pack charge and smoothly transitioning between the engine and motor power. All together, this results in a hybrid vehicle with both improved fuel economy and an enjoyable driving experience.

Unmanned ground vehicles (UGVs) will increasingly be used for tasks such as retrieving injured soldiers from a battlefield, transporting supplies, and towing other small vehicles and payloads. To date, the unmanned test community has not standardized on an apparatus or test operating procedure (TOP) specifically for evaluating the towing capacity of small unmanned ground vehicles. Draw-bar testing has been adapted by several groups to quantify small unmanned ground vehicle (SUGV) tow capacity; however, these devices are inherently limited to measuring peak static towing force. This paper describes an alternative method using a variable-resistance tow sled for quantifying the dynamic towing capacity of SUGVs. The tow sled contains a frontal skid plate and a rear axle and wheel arrangement. A weighted carriage is transferred from the rear of the sled to the front of the sled by a cable geared to the rear axle. As the sled is pulled along the ground, towing resistance increases in a controlled linear fashion. An encoder on the rear axle and a load cell in the tow chain provide motion and force data. Testing of the tow sled has been conducted on a TALON SUGV at the Southwest Research Institute (SwRI) Small Robot Test Facility and a MATILDA SUGV at the Joint Unmanned Systems Test, Experimentation, and Research (JOUSTER) site. / Master of Science

The aim of this thesis is to analyse a business model that is defined in two ways: company client and company company. The main point is ensuring of vehicle and emission testing of cars. In the first case, car owners are the clients, and in the second case, car repair shops are the clients. The theoretical part includes definitions of terms and descriptions of individual analyses and serves as a basis for the practical part where we can find internal and external analyses as well as descriptions of both forms of the business model. The outcomes of the analyses are then used to create a SWOT matrix. The conclusion of the thesis contains an evaluation of the data and results of all analyses, which can present a useful tool when deciding about any further development of the business idea.

The effect of center of gravity (CG) height and lateral and longitudinal off-centering on high-speed roll stability of A-double tractor trailers with 28-ft and 33-ft straight-rail and drop-frame trailers is evaluated through simulation and track testing. The changes in CG position due to the type of trailer (straight-rail vs. drop-frame) and laterally and longitudinally off-centered loads are considered. The simulation results show that imbalanced trailer loading induces roll instability and increases the likelihood of trailer rollover. Additionally, for equal loading conditions, the drop-frame trailers exhibit better roll stability than straight-rail trailers because of the lower CG. The simulation evaluation of 28-ft A-doubles is complemented with track testing of 33-ft trailers in alike (Drop-Drop and Straight-Straight) and mixed (Drop-Straight and Straight-Drop) arrangements of front and rear trailers, for various steering maneuvers that represent highway driving, such as exit ramp, obstacle avoidance, etc. The test trailers include specially designed load frames for emulating a loaded trailer in various loading conditions, outriggers for preventing trailer rollover, and durability structures for withstanding the torsional and bending moments resulting from the tests. Various sensors, including GPS, LiDAR units, accelerometers, string pots, and pressure transducers, are used, along with an onboard data acquisition (DAQ) system, for collecting the necessary data for post-analysis. Analysis of the test data indicates that the Drop-Drop configuration exhibits higher roll stability than the Straight-Straight configuration. For mixed trailers, the Drop-Straight configuration exhibits higher roll stability in exit ramps, but lower obstacle avoidance stability. Equipping the trailers with a roll stability control (RSC) system improves roll stability in terms of increasing the rollover threshold speed and tolerating more aggressive lane change steering maneuvers for A-doubles in various conditions. The RSC performance increases further when the brake application is synchronized between the two trailers to account for any lateral dynamic delay that naturally occurs. A novel interconnected RSC system is proposed to eliminate the lag between the RSC modules with a new control logarithm. The proposed RSC system increases the trailers' roll stability by 16% when compared with independent RSC systems that are commonly used for A-doubles. / Doctor of Philosophy / Commercial trucks play an indispensable role in transporting goods in society. A large percentage of the goods that we use daily or are delivered to our homes are transported on the nation's highways. Most often, the average automobile driver notices the presence of trucks on highways, at times with a bit of disdain. The public's perception appears to be formed by the fact that accidents involving commercial trucks are more publicized because they can cause more property damage, injuries, or even fatalities. The primary thrust of this research is to make the nation's highways safer by offering a better understanding of the dynamics of trucks with double trailers that are operated with a higher frequency on public highways. The double trailer configuration is often favored because of its larger cargo capacity and high modularity. However, their roll dynamics are not as well understood as the conventional tractor-semitrailers. Understanding the dynamics of double-trailer trucks is undoubtedly the very first step toward preventing or reducing the traffic accidents caused by rollovers. This study provides detailed analysis of roll dynamics for double trailers with imbalanced payloads. It also evaluates the effect of different types of trailers, such as drop-frame trailers (those with a "belly" in the mid-section of the trailer) and straight-rail trailers (those without a "belly") on their rollover propensity. The commercialized RSC system is evaluated for its effectiveness on the double-trailer truck. The evaluations are based on over 1,000 sets of tests in highly controlled conditions at the Transportation Research Center (TRC), a special facility for vehicle dynamic assessment in East Liberty, Ohio. It is found that the rollover dynamics of trucks with double trailers can be improved by having an awareness of the most favorable trailer arrangements according to their types of trailers and type of steering (exit-ramp or obstacle avoidance). In addition, this study provides the analysis of the commercialized RSC system for its effectiveness on the double-trailer truck. Lastly, a novel RSC system is proposed to further improve the effectiveness of the original RSC system.

The thesis presents an intermediate modelling approach to study transient behaviour of vehicle systems, with emphasis put on simplified yet accurate representation of important system elements. A representative non-linear vehicle model is developed in MA TLAB/Simulink environment, where non-linear characteristics of tyre, suspension and braking system are included to capture the dynamic behaviour of a vehicle under transient conditions. The novel aspect of this work is the application of a representative full vehicle-tyre-ABS integrated set-up to study the complicated interaction between tyre and anti-lock braking, under a range of demanding operating conditions, including combined cornering and braking. The modelling methodology involves development of low end vehicle models, based on the Newton-Euler formulation. Subsequently, an intermediate vehicle model is devised, where more details are incorporated such as additional DOF to capture the sprung mass motion in space, along with its non-linear interactions with the un-sprung masses, large angle effects, kinematics of steering/wheels and an appropriate tyre model suitable for transient manoeuvres. Particular attention is paid to the suspension system modelling, through inclusion of non-linear effects in springs, dampers, bump-stops, and anti-roll bars, along with the jacking and anti-dive effects using the virtual work method. The model also incorporates a hydraulic brake model, based on the reduced order brake system dynamics for realistic simulation of the braking manoeuvres. A complex multi-body ADAMS/Chassis model, with much greater level of detail, has also been established to extensively compare and enhance the realistic behaviour of the intermediate vehicle model. During the simulation exercise, the intermediate vehicle model has shown good agreement with the complex ADAMS model, thus justifying the accurate representation of vehicle.non-linear characteristics, particularly the suspension system. The realistic behaviour of the vehicle model is further ascertained with a reliable GPS enabled test vehicle, by performing number of manoeuvres on test tracks, including combined cornering and braking. A representative 4-channel conventional ABS system is modelled and integrated in the intermediate vehicle model. The ABS adopts generic peak seeking approach, employing wheel deceleration and brake slip as control variables. External braking inputs, in form of stepped pressure pulses, are also separately used to represent the transient braking system dynamics. In the current work, different transient tyre models based on the single point contact approach and using Magic Formula steady-state characteristics are applied, while studying the influence of their dynamic behaviour on the ABS system. By employing a representative ABS system in a multi-body vehicle model and considering the particularly demanding situation of combined braking I cornering, it is shown that the models which are adequate for pure braking might struggle when the complicated full vehicle dynamics are excited. It is shown that the first order relaxation length approach may not be sufficient to fully satisfy the requirements of an ABS braking, especially if the relaxation length is not modelled as a variable dependent on tyre slip. In comparison, the modelling approach, where the carcass compliances and contact patch properties are explicitly represented, can handle the oscillatory tyre behaviour associated with ABS braking, in a far more accurate manner. In comparison to the earlier studies, which were mostly conducted for straight-line braking, this thesis stresses the fact that the tyre behaviour can be influenced by the complex interaction of handling and braking, and hence the effect should be captured while investigating or evaluating the performance of a tyre model in relation with ABS simulation.

The thesis outlines a hierarchical modelling methodology for investigation in vehicle dynamics, in particular for combined ride and handling manoeuvres. The methodology involves the use of detailed multi-degrees of freedom models of vehicles with the inclusion of sources of non-linearity, using a multi-body approach, based on Lagrangian dynamics for constrained systems. It also includes the use of simpler and task-specific models, formulated in Newton-Euler approach. These simpler models with lower degrees of freedom, but with appropriate level of detail are more efficient in the study of specific, but non-trivial problems such as transient behaviour of vehicles in combined ride and handling, as encountered in many routine daily manoeuvres. The modelling methodology is supported by careful vehicle testing, both for validation of the proposed approach, and assessment of the extent of applicability of simple, intermediate and multi-degrees of freedom full-vehicle models. Certain important vehicle handling and ride characteristics in pitch plane dynamics, roll behaviour, vehicle body bounce and combination of these have been studied, as well as the effectiveness of restraining action of chassis elements, such as the semileading and trailing arms for passive control of vehicle squat and dive motions, arising from acceleration from coast to drive and deceleration/brake of vehicle from drive to coast. Combined pitch and bounce motions have been studied when negotiating speed traps such as bumps, which also combine with significant body roll when single event obstacles of this kind are introduced. The novelty of the research is in the detailed integrative numerical-experimental approach, and the development of intermediate models that adequately predict vehicle behaviour under steady and non-steady conditions for a wide range of ride and handling manoeuvres. The investigations have culminated in a significant number of findings of practical use, particularly the ineffectiveness of anti-squat and dive features when combined pitch and bounce motions limit the usefulness of these devices. On the contrary, excessive roll dynamic behaviour of the vehicle is effectively palliated by the anti-roll bar, even under complex combined pitch, roll and body bounce such as those experienced in negotiating single event speed bumps. Good agreement is found between the predictions of the intermediate model and those of the multi-body model and the actual vehicle tests, particularly for pitch and bounce dynamics.