In this thesis project, brake performance of heavy vehicles is improved by the development of new wheel-based functions for a longitudinal slip control braking system using novel Fast Acting Braking Valves (FABVs). To achieve this goal, Volvo Trucks' vehicle dynamics model has been extended to incorporate the FABV system. After validating the updated model with experimental data, a slip-slope based recursive least squares friction estimation algorithm has been implemented. Using information about the tire-road friction coefifcient, the sliding mode slip controller has been made adaptive to different road surfaces by implementing a friction dependent reference slip signal and switching gain for the sliding mode controller. This switching gain is further optimized by means of a novel on-line optimization algorithm. Simulations show that the on-line friction estimation converges close to the reference friction level within one second for hard braking. Furthermore, using this information for the optimized controller has resulted in reduction of braking distance on most road surfaces of up to 20 percent, as well as in most cases a reduction in air usage.

Automotive transmission rattle is the noise generated due to impacts between manual transmissions meshing gear teeth in the presence of backlash. It is considered to be a Noise, Vibration and Harshness (NVH) phenomenon and is originated due to combustion irregularities (engine order vibrations), especially in diesel vehicles. This thesis focuses in the case of creep rattle for the MMT6 Ford Getrag transmission (six speeds plus reverse) with a DW10b, 4-cylinder, 4-stroke, 2.0 litres diesel engine. This particular rattle condition is fundamentally similar to any other where an engaged gear is pertained (drive, over-run or float), with the 1st or 2nd gear engaged at a very low engine speed. The numerical models include an initial single degree of freedom (DoF) simulation. It comprises either of the engaged gear pair under Hertzian contact conditions or of a loose gear pair under hydrodynamic regime of lubrication. Once the validity of this model is established and correlated with the results obtained from a single gear pair test rig, simulations of increasing complexity can be envisaged. A 7 DoF numerical model is, therefore, developed. The Hertzian contact model still prevails for the engaged gear pair, whereas an analytical hydrodynamic solution is implemented for the remaining 6 loose gear wheels and Petrov s law is applied to the needle bearings retaining the gear wheels. With the aim of accommodating a fully lubricated model of all the tribological conjunctions, an analytical elastohydrodynamic (EHL) Grubin type algorithm is employed. Also, the energy equation is analytically solved for hydrodynamic and elastohydrodynamic conjunctions, based on the assumptions dictated by the Peclet number. Therefore, under hydrodynamic conditions, the energy equation is governed by viscous heating and convective cooling, whereas in the EHL conjunctions the governing terms are viscous and compressive heating, together with conductive cooling. The retaining needle bearings follow the same heat generation mechanism as journal bearings. The effective viscosity, as obtained from the Houpert s equation accounting for pressure and thermal effects, is fundamental for the study of the friction in the contact. The hydrodynamic contacts are only governed by viscous friction, whereas EHL conjunctions exhibit asperity iv interactions as well as viscous effects. The results obtained from this new 7 DoF model are then compared to the experimental measurements taken from the vehicle tests and various purpose-built drivetrain rigs. A metric named Impulsion Ratio is hereby introduced, aiming to shed some light into the predictions obtained by the various models presented. This metric is the ratio of driving over resistive forces acting on each individual gear wheel. Its use is tested to predict single or double-sided rattle scenarios and, therefore, ascertaining higher and lower rattle levels. The 13 DoF model from which these conclusions were obtained includes shafts planar translation and rocking moments. The rolling element bearings supporting the shafts are, therefore, modelled to capture the inherent frequencies arising from their motion. The final model introduces the effects of transient thermo-elastohydrodynamics. This 7 DoF dynamic model accounts for a numerical solution of Reynolds equation with Elrod s cavitation algorithm for simultaneous teeth in mesh. The results obtained validate the previously used Grubin assumption by comparing the predicted central film thickness along the full mesh of one tooth. Also, the effect of starved input conditions and thermal and isothermal solutions are studied.

[pt] A ascensão da tecnologia dos automóveis elétricos no mercado mundial induz a pequena indústria dos karts recreativos a percorrer caminhos semelhantes. O comércio dos karts recreativos com motorização elétrica já existe, mas ainda é incipiente. A propulsão elétrica no kart proporcionaria, entre outras vantagens, a possibilidade de inserção de tecnologias automotivas já conhecidas, tais como um sistema de frenagem sem bloqueio e um sistema de controle de estabilidade. O sucesso da inserção destas tecnologias em um kart seria um avanço muito significativo para um produto que apresenta avanços tecnológicos modestos desde a sua criação. Contudo, para obter o sucesso tecnológico do kart tradicional, o modelo elétrico depende da aplicação de métodos modernos de engenharia e da metrologia, tal como a modelagem matemática computadorizada, objetivo principal desta dissertação. Assim, esta dissertação apresenta inicialmente as características físicas e dinâmicas de um kart movido à combustão, obtidas por meio de ensaios e medições realizadas em pista e em bancada. Utilizou-se como instrumento principal de medição o equipamento Alfano (marca registrada) Pro III Evo, cujas indicações foram submetidas a processos simplificados de validação. Desenvolveram-se então, com base nos dados experimentais, modelos matemáticos computadorizados em Matlab/Simulink (marca registrada) que simulam o comportamento dinâmico do kart, e os resultados das simulações foram comparados aos resultados das medições feitas em pista, para fins de validação. A propulsão à combustão do modelo computacional validado foi então substituída por propulsão elétrica, e simulações do novo modelo foram realizadas, permitindo a observação do comportamento dinâmico simulado de um kart elétrico. / [en] The rise of electric car technology on the world market induces the small recreational go-karts industry to follow similar paths. The trade of recreational gokarts with electric motorization already exists but is still incipient. The electric drive in the go-kart would provide, among other advantages, the possibility of insertion of known automotive technologies, such as an Anti-lock Braking System and a Stability Control System. The successful insertion of these technologies into a gokart would be a very significant breakthrough for a product that has undergone modest technological advances since its inception. However, to obtain the technological success of traditional go-kart, the electric model depends on the application of modern methods of engineering and metrology, such as computerized mathematical modeling, the main objective of this dissertation. Thus, this dissertation initially presents the physical and dynamic characteristics of a combustion driven go-kart, obtained through tests and measurements made on track and bench. The Alfano (registered) Pro III Evo equipment, whose indications were submitted to simplified validation procedures, was used as the main measuring instrument. Based on the experimental data, Matlab / Simulink (registered) computerized mathematical models simulating the dynamic behavior of the go-kart were then developed, and the results of the simulations were compared to the results of the measurements made on the track for validation purposes. The combustion propulsion of the validated computational model was then replaced by electric propulsion, and simulations of the new model were performed, allowing the observation of the simulated dynamic behavior of an electric go-kart.

Vehicle simulators are often built from scratch, using well-established software frameworks with custom vehicle models. Since the development of a simulator is a very time consuming process,  the purpose of this thesis paper was to explore a different alternative by evaluating the open-source vehicle system ChaosVehicle (CV) in Unreal Engine 5. The goal was to build a simulator using CV and assess its performance in imitating certain aspects of a three-wheeled electric vehicle, including acceleration, coasting and braking behaviors in a straight line.The simulator was set up according to the data provided by the vehicle manufacturer, OMotion. By comparing the simulations with real world driving data, it was determined that the simulator achieved a relative error below 16% in imitating the coasting behavior of the real vehicle. Further, with regards to the brake performance, the simulator has managed to achieve a relative error of below 15% when not accounting for velocities below 10 km/h. Due to the noise present in the real world driving data, it was inconclusive as to whether the simulator had accurately predicted the acceleration behavior of the  real vehicle. After a preliminary analysis of the plugin, it was discussed whether CV was as extensible as hypothesized. While the framework is open-source, it was difficult to fully grasp the system due to incomplete documentation of the source code and the user interface. Further work in mapping how the physics model in CV is integrated to the game engine would shed some light on this matter.

Die Marktbedingungen in der Automobilindustrie sind durch kürzere Entwicklungszeiträume, eine zunehmende Anzahl an Komfortfunktionen und Fahrzeugderivaten sowie steigende Erwartungen an Qualität, Effizienz und Sicherheit geprägt. Die reale Erprobung ist ein kritischer Pfad im Entwicklungsprozess. Die vorliegende Arbeit beschreibt ein neues Prüfsystemkonzept für die Komponentenerprobung, welches diesen Anforderungen Rechnung trägt. Das Herzstück ist eine softwarebasierte Systemarchitektur zur Automatisierung von Prototypentests. Schwerpunkte sind die Flexibilität in der Praxisanwendung, die Ausweitung der Messdatenerfassung mit zweckmäßiger Verwaltung zur Bauteilüberwachung und Fehlerrekonstruktion sowie eine aufgabenorientierte Schnittstelle zur Integration von Robotern. Diese übernehmen die mechanische Betätigung von beweglichen Fahrzeugkomponenten. Anhand von zwei konkreten Beispielen, einem Prüfstand zur Absicherung von Fahrzeugtüren sowie einem Prüfstand für Steifigkeitsmessungen wird die Praxistauglichkeit nachgewiesen.

Die Marktbedingungen in der Automobilindustrie sind durch kürzere Entwicklungszeiträume, eine zunehmende Anzahl an Komfortfunktionen und Fahrzeugderivaten sowie steigende Erwartungen an Qualität, Effizienz und Sicherheit geprägt. Die reale Erprobung ist ein kritischer Pfad im Entwicklungsprozess. Die vorliegende Arbeit beschreibt ein neues Prüfsystemkonzept für die Komponentenerprobung, welches diesen Anforderungen Rechnung trägt. Das Herzstück ist eine softwarebasierte Systemarchitektur zur Automatisierung von Prototypentests. Schwerpunkte sind die Flexibilität in der Praxisanwendung, die Ausweitung der Messdatenerfassung mit zweckmäßiger Verwaltung zur Bauteilüberwachung und Fehlerrekonstruktion sowie eine aufgabenorientierte Schnittstelle zur Integration von Robotern. Diese übernehmen die mechanische Betätigung von beweglichen Fahrzeugkomponenten. Anhand von zwei konkreten Beispielen, einem Prüfstand zur Absicherung von Fahrzeugtüren sowie einem Prüfstand für Steifigkeitsmessungen wird die Praxistauglichkeit nachgewiesen.