This dissertation is focused on proposal for simplified data analyze approach for sport-car vehicle dynamic evaluation with relationship to possibility for qualified estimation of set-up parameters influence for overall vehicle performance. In common practice can be usual overlapping effect caused by concurrent changes of car setup elements if performed in the same moment with resulting in not correct or hardly definable process determination for evaluation and decision about next steps in car development. For analyze of these multidimensional data is then chosen process with approach by Linear Regression Model (LRM). In dissertation is proposed basic philosophy with concern on specificity of car vehicle dynamics, performed experiment with defined inputs including analyze and interpretation method of obtained outputs. This methodic take into account also possibility for general application of multidimensional data analyses not only in motorsport, but as well for dynamic behavior diagnostics of technical systems where finding of optimal running condition depends on multi-parametric setup whose combination must reflect often changes of outer conditions too.

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Active anti-roll bars have recently found greater acceptance among premium car manufacturers and optimal application of this technology has emerged as an important field of research. This thesis investigates the potential of implementing active anti-roll bars in a passenger vehicle with the purpose of increasing customer value. For active anti-roll bars, customer value is defined in terms of vehicle’s ride comfort and handling performance. The objective with this thesis is to demonstrate this value through development of a control algorithm that can reflect the potential improvement in ride comfort and handling. A vehicle with passive anti-roll bars is simulated for different manoeuvres to identify the potential and establish a reference for the development of a control algorithm and for the performance of active anti-roll bars. While ride is evaluated using single-sided cosine wave and single-sided ramps, handling is evaluated using standardized constant radius, frequency response and sine with dwell manoeuvres.The control strategy developed implements a combination of sliding mode control, feed forward and PI-controllers. Simulations with active anti-roll bars showed significant improvement in ride and handling performance in comparison to passive anti-roll bars. In ride comfort, the biggest benefit was seen in the ability to increase roll damping and isolating low frequency road excitations. For handling, most significant benefits are through the system’s ability of changing the understeer behaviour of the vehicle and improving the handling stability in transient manoeuvres. Improvement in the roll reduction capability during steady state cornering is also substantial. In conclusion, active anti-roll bars are undoubtedly capable of improving both ride comfort and handling performance of a vehicle. Although the trade-off between ride and handling performance is significantly less, balance in requirements is critical to utilise the full potential of active anti-roll bars. With a more comprehensive control strategy, they also enable the vehicle to exhibit different driving characteristics without the need for changing any additional hardware.

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This thesis aims to explore if multibody simulations is a suitable method to investigate vibrations in the steering system of trucks. Vibrations in the steering system and subsequently in the steering wheel is a common issue that automotive manufacturers face. The vibration levels in the steering wheel are in some countries regulated and some vibration phenomena can even cause issues with the handling properties of the whole vehicle. Therefore being able to predict and reduce these with the help of multibody simulations would be of great value. The thesis does this by comparing the simulations to measurements. It investigates what parts can be approximated as rigid, what the effects different numerical solvers have and compares different driving scenarios. This can however be quite challenging, one reason being that the differential equations arising when performing multibody simulations of trucks are very stiff. The numerical challenges of this must be overcome while still keeping the resolution of the accelerations in the solution high enough to still be representative of reality. The thesis also explains how to mathematically model a physical system such that the numerical analysis of it can be efficient. The results show that the success of multibody simulations is very dependent on the test case. However, they also show that together with physical measurements multibody simulations can be a powerful complementary tool. The thesis also presents improvements that could be made to the model as well as certain key areas that need to be studied more in order to align the multibody simulations results with measurements. The multibody simulations software used to perform the calculations and the modelling in the report is Adams developed by Hexagon AB. / Den här rapporten syftar till att ge inblick i om flerkroppssimuleringar kan vara ett användbart verktyg för att undersöka styrsystemsvibrationer i lastbilar. Dessa vibrationer är orsaken till en mängd styrningsproblem samt att rattvibrationer har lagkrav att inte vara för stora. Att kunna förutspå och efterlikna dessa vibrationer med flerkroppssimulering skulle därmed vara till stor fördel. Detta undersöks genom att jämföra simuleringarna med mätdata. Det undersöks vilken påverkan stelkroppsapproximationer av vissa komponenter har, påverkan av olika numeriska integrationmetoder samt steglängder och även olika körningslastfall. Att genomföra flerkroppssimuleringar av lastbilar är dock inte alltid helt enkelt, på grund av differentialekvationernas styva karaktär uppstår ofta konvergensproblem. Ska man sedan använda resultaten för att undersöka styrsystemsvibrationer måste man överkomma dessa konvergensproblem men bibehålla en tillräckligt fin upplösning av resultatet för att resultatet fortfarande ska vara representativt av den fysiska lastbilens dynamiska egenskaper. Rapporten beskriver även hur man kan gå tillväga för att matematiskt modellera ett fysisk system så att det effektivt går att utföra dynamisk analys av det. Resultaten visar att flerkroppssimulering kan vara väldigt beroende på vad körfallet är, med vissa körfall där simuleringar och mätningar stämmer väl överens och andra där detta inte är fallet. På grund av detta kan det vara otillräckligt att endast använda flerkroppssimulering för att utvärdera styrsystemsvibrationer, men resultaten visar att tillsammans med mätdata kan flerkroppssimulering vara ett kraftfullt komplement. I rapporten presenteras även exempel av viktiga komponenter att ta hänsyn till för att bättre kunna simulera styrsystemsvibrationer samt områden där mer forskning har potential att förbättra flerkroppssimuleringar i hänsyn till styrsystemsvibrationer. Mjukvaran som används för att utföra flerkroppssimulering är Adams som utvecklas av Hexagon AB.

The brake system is critical for ensuring safe driving and has been the focus of development for many years. Pneumatic braking technology is commonly used in heavy vehicles,but it results in energy wastage and high service costs. Some countries mandate auxiliarybraking systems to assist in stopping the vehicle in addition to service brakes. One suchsystem is the regenerative braking system, which captures kinetic energy from braking andconverts it into electrical energy. Retarders are another commonly used auxiliary brakingsystem. These systems are essential due to heavy vehicle weight, which can weaken servicebrake performance.This thesis focuses on estimating net forces on the truck’s driven axle to understandhow auxiliary braking systems and vehicle traction affect the normal force on the drivenwheel axle. The expected result can assist in maintaining the slip ratio and increasing thelife span and performance of brakes.Scania uses a function to estimate forces on the driven axle and drive wheel slip. Theyneed to determine the normal force on the axle to improve performance of auxiliary brakingsystems, but tests showed that for the same specified slip ratio, the auxiliary braking forcerequired was smaller than that in an acceleration state. Scania believe that dynamic axleload transfer may be the cause, so a 6x2 electrified truck will be investigated in this thesis.The obtained results show the driven wheel axle’s behavior during different dynamicalscenarios.This research aimed to develop a model that can accurately simulate a truck’s movement and estimate the ground reaction force in response to variations in the scenario of thecontrol signal. By studying the quarter car model, bounce-pitch and half car model, theresearchers were able to obtain a model represented by 5 ODEs, which predicts the wheelaxle normal force. To verify the model, data from the CAN bus and measurements using ascale were collected and compared with the model’s output. The Mean Squared Error canbe used to evaluate and compare the model’s performance, and the results showed that themodel provides a reasonable estimate of the normal force on all axles. The study also analyzed the factors that contributed to the errors in the results. The behavior of the normalforce for each wheel axle during acceleration and braking was illustrated, explaining howthe normal force distribution becomes mirrored compared to the acceleration state duringbraking. The study’s discussions enhance the validity of the observed behavior and thereliability of the results.

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The research on autonomous vehicles, and more specifically cooperation between autonomous vehicles, has become a prominent research field during the last cou- ple of decades. One example is the combination of an unmanned aerial vehicle (UAV) together with an unmanned ground vehicle (UGV). The benefits of this are that the two vehicles complement each other, where the UAV provides an aerial view and can reach areas where a ground vehicle can not. Furthermore, since the UAV has a limited range, the UGV can then serve as transport and recharge sta- tion for the UAV. This master thesis studies how model predictive control (MPC) can be used to land a UAV on a moving UGV.  A linear MPC is chosen, since previous work using this has shown promising results. The UAV is chosen to be controlled using commands in pitch, roll and climbing rate. The MPC is designed as a decoupled controller, with a separate horizontal and vertical controller. This allows for a spatial constraint to be im- plemented, which constrains the UAV from entering ground level before arriving above the UGV. It also constrains the UAV from potentially hitting protruding ob- jects on the UGV. The horizontal controller uses a simple planner, which guides the UAV to land on the UGV from behind.  The MPC is evaluated using a additive white Gaussian noise (AWGN) sen- sor error model with zero mean. The scenario used is that the UAV starts 50 m from the UGV, and the UGV starts driving in a given direction turning randomly. The MPC lands successfully in 100 % of the simulations for a wide range of tun- ings. The MPC maintains the same landing statistics with a delay in the sensor information of up to 500 ms. The AWGN could be increased while maintaining successful landings, however with significantly more retakes and longer landing times. Lower AWGN variance only slightly improves performance, suggesting that the MPC is quite robust towards high variance in the state estimation.  The MPC is also compared to a PID controller. The MPC has significantly shorter landing times. The PID has a more oscillatory control signal, however, the PID has a lower variance in landing positions, but a slightly less centered mean on the UGV. The overall results show that an MPC can be used to achieve a flexible controller that can be tuned and reformulated to fit the situation, and performs as good or better compared to a PID controller.  The hardware tests show promising results for the implementation of the MPC. The controller is not tuned and no system identification is done specifi- cally for the physical UAV, suggesting that the controller is robust for varying settings. Even though the UAV never lands on the UGV, the visual behavior and control signal plots suggest that it would be able to land. However, these tests are performed using global navigation satellite system state estimation on a sta- tionary UGV, therefore further tests need to be performed in more challenging scenarios.

The electromechanical design and development of a sophisticated roller rig testing facility at the Railway Technologies Laboratory (RTL) of Virginia Polytechnic and State University (VT) is presented. The VT Roller Rig is intended for studying the complex dynamics and mechanics at the wheel-rail interface of railway vehicles in a controlled laboratory environment. Such measurements require excellent powering and driving architecture, high-performance motion control, accurate measurements, and relatively noise-free data acquisition systems. It is critical to accurately control the relative dynamics and positioning of rotating bodies to emulate field conditions. To measure the contact forces and moments, special care must be taken to ensure any noise, such as mechanical vibration, electrical crosstalk, and electromagnetic interference (EMI) are kept to a minimum. This document describes the steps towards design and development of all electromechanical subsystems of the VT Roller Rig, including the powertrain, power electronics, motion control systems, sensors, data acquisition units, safety and monitoring circuits, and general practices followed for satisfying the local and international codes of practice. The VT Roller Rig is comprised of a wheel and a roller in a vertical configuration that simulate the single-wheel/rail interaction in one-fourth scale. The roller is five times larger than the scaled wheel to keep the contact patch distortion that is inevitable with a roller rig to a minimum. This setup is driven by two independent AC servo motors that control the velocity of the wheel and roller using state-of-the-art motion control technologies. Six linear actuators allow for adjusting the simulated load, wheel angle of attack, rail cant, and lateral position of the wheel on the rail. All motion controls are performed using digital servo drives, manufactured by Kollmorgen, VA, USA. A number of sensors measure the contact patch parameters including force, torque, displacement, rotation, speed, acceleration, and contact patch geometry. A unified communication protocol between the actuators and sensors minimizes data conversion time, which allows for servo update rates of up to 48kHz. This provides an unmatched bandwidth for performing various dynamics, vibrations, and transient tests, as well as static steady-state conditions. The VT Roller Rig has been debugged and commissioned successfully. The hardware and software components are tested both individually and within the system. The VT Roller Rig can control the creepage within 0.3RPM of the commanded value, while actively controlling the relative position of the rotating bodies with an unprecedented level of accuracy, no more than 16nm of the target location. The contact force measurement dynamometers can dynamically capture the contact forces to within 13.6N accuracy, for up to 10kN. The instantaneous torque in each driveline can be measured with better than 6.1Nm resolution. The VT Roller Rig Motion Programming Interface (MPI) is highly flexible for both programmers and non-programmers. All common motion control algorithms in the servo motion industry have been successfully implemented on the Rig. The VT Roller Rig MPI accepts third party motion algorithms in C, C++, and any .Net language. It successfully communicates with other design and analytics software such as Matlab, Simulink, and LabVIEW for performing custom-designed routines. It also provides the infrastructure for linking the Rig's hardware with commercial multibody dynamics software such as Simpack, NUCARS, and Vampire, which is a milestone for hardware-in-the-loop testing of railroad systems. / Ph. D.