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ÖgeModel reference adaptive controller design with augmented error method for lane tracking(Graduate School, 2023-11-20)At the beginning of the automobile industry history, automobiles were simple mechanical systems. Starting from Ferdinand Verbiest's steam-powered vehicle in 1672, called a toy, automobiles have evolved into complex machines. Essential inventions, such as the design of the first internal combustion-powered vehicle by François Isaac de Rivaz in 1808 and the gasoline-powered automobile by Karl Friedrich Benz in 1886, automobiles became available for everyday use. Especially the introduction of the Ford Model T by the Ford Motor Company in 1908, which was the first mass-produced commercial automobile, automobiles became common on roads. Thus, the safety and riding comfort specifications became significant factors for automobile producers in the automobile industry. In the early 20th century, the pace of evolution increased dramatically thanks to the computerization and electronics in automobiles, which led to the introduction of Electronic Control Units (ECUs) and onboard computers, allowing for more precise control over engine performance and emissions and vehicle stability. Moreover, these computers and electrical components were used to design driver assistance systems introduced for driving comfort and safety during the 20th century. The initial features, such as anti-lock braking system (ABS) and cruise control (CC), were worked effectively. Later, these features were improved, advanced, and varied for different purposes under autonomous driving. Recently, the automotive industry has undergone a distinctive transformation towards autonomy, which governments and leading companies like Tesla and Google support. Advanced driver assistance systems (ADAS) play a crucial role in autonomous driving. ADAS includes features implemented in vehicles to enhance safety and riding comfort by improving user awareness and controlling vehicle movement. Driver support systems can be categorized from various perspectives, including active, passive, safety, and comfort. Active driver assistance systems assume control of certain vehicle functions, while passive control systems warn the driver. According to the vehicle control point of view, ADAS is covered under two main categories: longitudinal and lateral motion control. Features like ACC and AEBS, for example, are associated with controlling the longitudinal motion of a vehicle, primarily focusing on speed and distance management. On the other hand, LKA/LCA and BSD features are within the domain of lateral motion control, mainly concerned with maintaining proper alignment within a lane and detecting vehicles in adjacent blind spots. Within the scope of this study, an adaptive controller is designed for lane tracking of autonomous vehicles. The controller algorithm aims to center the vehicle on the lane by calculating the required front steering angle. The controller's performance is simulated and evaluated, and finally, further tasks are determined. Lane tracking control design is handled either with a model-free or a model-based approach in the literature. Model-free methods provide an alternative option when creating models becomes inaccurate and challenging. These control strategies typically rely on data-driven techniques such as supervised learning, reinforcement learning, and fuzzy logic control. Model-based approaches, such as MPC, SMC, LQR, and $H_\infty$, on the other hand, use the mathematical representation of the vehicle's lateral motion, which plays a significant role in controller design. Simulation of the vehicle system using this representation provides a clear perspective for the evaluation of designed controller performance and calibration. Vehicle models for lane tracking controller design are categorized within various aspects. While the mathematical representation of a vehicle, whether it is linear or non-linear, is in one category, its configuration type is the second one. Three vehicle model configuration types are available in the literature: geometric, kinematic, and dynamic vehicle models. Each of these configuration types has advantages and disadvantages that must be considered while designing a controller. The bicycle dynamic vehicle model is the popular representation used in this thesis. Lateral path error is derived as the function of vehicle lateral motion state variables (lateral, longitudinal velocity, and yaw angle of the vehicle) on the ego lane, which is the output of the control system according to the bicycle model. Then, this derived model is used to determine the adaptive control law to achieve the desired tracking performance. The adaptive control method is one of the most promising methods to create reliable solutions to the difficulties faced by autonomous vehicles in lane tracking. Although different types of adaptive control design methods are available in the literature, model reference adaptive control (MRAC) is the most suitable in terms of clarity and low computational burden, as well as real-time application. In this thesis, it is clearly seen that the derived vehicle model is a perfect fit for the adaptation of feedforward gain with the output feedback based on the passivity. However, due to that the derived model's transfer function, based on the parameters of an autonomous large-size vehicle, is not SPR makes the model unsuitable for model reference adaptive controller design. As a solution, the augmented error method is used to enable the application of the passivity approach to determine the adjustment rules of controller parameters. Thus, the controller design, which ensures the input-output stability with MRAC, is derived based on the augmented error method. As a result, it is seen that the model reference adaptive controller system with augmented error method showed a perfect tracking performance according to the simulations on Simulink. Considering similar studies, the control signal obtained in the simulation showed that the model is applicable for real-time application.
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ÖgeComparative analysis of torque vectoring control strategies in electric vehicles(Graduate School, 2024-06-11)Vehicle dynamics control systems have an important role in accident prevention by decreasing the difference between the desired and actual vehicle response. Torque Vectoring Control is one of these systems which is developed to enhance the steering and handling performances of vehicles. This thesis focuses on the comparison of the control strategies for the potential of improving the steering and handling performances of electric vehicles through torque vectoring control systems. In this thesis, a non-linear multi-body dynamics model is used to represent the real electric vehicle. This vehicle model adopts three independently controllable electric motors; one of them is on the front axle for traction and the other two are on the rear axle. With the help of these two motors on the rear axle, the yaw moment can be controlled with the torque difference between the two electric motors. Furthermore, the control system needs a target value to follow the desired behavior of the system. To achieve this aim, the lateral dynamics reference generation has been included. When working with the vehicle lateral dynamics in the study, the yaw rate response is considered as a representative of steering and handling performance. Then, the system steering and handling capabilities using different maneuvers are evaluated with closed-loop test cases performed in a simulation environment. Various controllers can be used to assess the steering and handling performance on the vehicle. In the first part of this thesis study, the effects of PID controller parameters on system performance for a single maneuver are examined, and then these parameters are adjusted to minimize the integral square error performance metric. The durability of this optimal controller under maneuver changes is also investigated. Simulation results show that under different maneuvers, particularly at high speeds and steering angles, the system performance significantly deteriorates. To overcome this problem, possible maneuvers the vehicle might encounter are determined, and then optimal PID controller parameters are found for each maneuver to minimize the integral square error performance metric. Using the optimal PID parameters found for possible maneuvers, an adaptive PID controller design is proposed with the help of the cubic spline method. The performance of the adaptive PID controller adapted to speed and steering angle is tested under various maneuver changes, yielding satisfactory results. In the second part of the thesis study, the effects of a fuzzy PID controller on system performance are examined due to its success in controlling nonlinear systems. For this purpose, fuzzy PID parameters, i.e. input-output scaling factors are found using the rule table and membership functions from the literature to minimize the integral square error, similar to the optimal PID controller. The fuzzy PID controller is compared to the optimal PID controller using a similar maneuver. Although the fuzzy PID controller does not produce superior results for a single maneuver compared to the optimal PID controller, it shows quite satisfactory results when faced with maneuver changes. The reason for the fuzzy PID controller not producing superior results for similar maneuvers is that the rule table and membership functions from the literature are not suitable for the system. For this purpose, the output membership functions are adjusted (shifted outward and inward), and then a fuzzy PID design is designed for a similar maneuver. When the output membership functions are shifted outward, the fuzzy PID controller produces superior results compared to the optimal PID controller.
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Ögeİleri sürücü destek sistemleri için bir fonksiyonel güvenlik uygulaması(Lisansüstü Eğitim Enstitüsü, 2022-05-26)İleri Sürücü Destek Sistemleri üzerinde ISO 26262'nin halihazırda var olan versiyonunun yetersizliği sonucunda ortaya çıkan yeni bir fonksiyonel güvenlik metodolojisi gerekliliği sonucunda tezin ilk amacı ortaya çıkmıştır. Bu amaç, ISO 26262'nin bu yeni teknolojiye uyarlanabilir bir versiyonunu ortaya koymaktır. Bunun için, var olan ISO 26262 standardizasyonuna, İleri Sürücü Destek Sistemleri ve tarihçesine ve ISO 26262'nin uygulama adımlarına değinilmiştir. Akabinde, bütün bu bilgiler ışığında İleri Sürücü Destek Sistemlerinde yaygın bir sistem olan İleri Acil Frenleme Sistemi (AEBS) fonksiyonu üzerinde örnek bir çalışma gerçekleştirilerek uyarlanan metodoloji tanıtılmıştır. İleri Acil Frenleme Sistemi, genellikle radar ve kameranın birlikte kullanılarak otomobil, motosiklet, yaya ve bisiklet gibi hedeflerin birlikte algılandığı sensör füzyonunun aktif olarak kullanıldığı bir fonksiyondur. Radarlar otomobilleri seçme konusunda daha efektif iken, kamera yaya tipi hedefleri seçmede daha büyük başarı göstermektedir. Bütün bu algılamanın gerçekleştiği karmaşık sistemlerde fonksiyonel güvenliğin gerekliliği tartışılmazdır. Bununla birlikte yollarda meydana gelen kazaların çoğunluğunun sürücü dikkatsizliğinden kaynaklandığı düşünülürse İleri Acil Frenleme Sistemi gibi akıllı bir teknolojinin fonksiyonel güvenliğin gerçekleştirildiği koşullarda trafik kazalarını büyük ölçüde engelleyeceği gerçeği yadsınamazdır. Dolayısıyla tezde otomotiv sektörüne daha büyük bir fayda sağlaması bakımından örnek fonksiyon olarak İleri Acil Frenleme Sistemi fonksiyonu seçilmiştir. Tezde ikincil bir amaç olarak hem İleri Sürücü Destek Sistemlerinin hem de fonksiyonel güvenliğin sektörde önem kazanmasıyla birlikte trendleşen bu iki alanın terminolojisinin Türkçe bir tez vasıtasıyla literatüre kazandırılarak Türkçe bir kaynak elde etmek hedeflenmiştir. Bu bağlamda ayrıntılı görseller ve kısaltmalarla tez Türk otomotiv sektörü için bir kaynak oluşturmaktadır.
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ÖgeBattery management system design with embedded electrochemical impedance spectroscopy(Graduate School, 2023-04-27)Humanity is developing day by day in engineering and technical fields. Engineers and scientists all over the world are trying to take humanity one step further. As a result of these studies, the technology provides comfort in our daily lives. One of the best examples of this are transportation, mobility and automotive. Each year, the studies progressing cumulatively in this field have pioneered the presentation of more developed cars than the previous years, and to populate different transportation methods and concepts in our lives. Each development has been formed as a result of some needs. One of the most important motivations in the field of automotive is user requests, the limited resources and the environmental sensitivity. The transition to electric vehicles, one of the biggest revolutions in transportation, has undoubtedly accelerated due to the depletion of fuel resources and the environmental sensitivity. Fuels used to operate internal combustion vehicles are obtained from petrol. While the formation of a petrol reserve takes for thousands of years, the current reserves are running out. Considering the demand that will rise in transportation due to the population and industrialization increase over time, it is predicted that the petrol reserves will be drained in the coming years. In addition, as a result of reactions inside the internal combustion engine, harmful gases are produced and released into world atmosphere. These gases, which are released from millions of vehicles, accumulate in the atmosphere and disrupt the balance of nature. Therefore, humanity has now become unable to lean on to petrol fuels and have been in search of new fuel sources. In this context, the most innovative transportation methods seem to be hydrogen and electrical based. While the comparison of these two methods with each other is the subject of a separate study, this study will focus on the electrical transportation method and the batteries to be used in these means of transportation. Transportation has been mainly provided by internal combustion vehicles until today. This naturally allowed many engineers working on this field to accumulate a lot of knowledge cumulatively. Over the years, engineers have solved the problems in the designs one by one and have reached the present knowledge level by pushing the limits of the existing technology. There have been many developments in internal combustion engines and vehicles in areas such as safety, efficiency, practicality and comfort. However, electric vehicles that have just started to become widespread have opened a new page. Compared to internal combustion propulsion systems, studies on electric propulsion systems are still in their infancy. Engineers and scientists are conducting a lot of work to fill the gap in this field. One of the most basic components of electric vehicles are batteries. When we compare one to one with internal combustion vehicle, the battery group corresponds to the fuel tank of the vehicle. The first factors for the user, such as the range of the electric vehicle, the charge time and the performance at different temperatures, are completely related to the battery. When these factors are examined, they are all disadvantaged xx compared to internal combustion vehicles. This offers a negative effect for the market share of electric vehicles. While the criterias mentioned are the factors that the user will experience directly, there is also a factor that the user cannot experience, but in fact, which is even more important than all of them, which is safety. As can be seen from time to time, electric vehicles may caught fire while charging or in a traffic accident. It is not possible to extinguish it when a battery flames. Therefore, this is a great danger for both the vehicle's user and for those around. These situations show that there are many more things to develop in terms of both safety and user experience in the batteries of electric vehicles. Today, Li-ion type cells are widely used in the batteries of electric vehicles. These cells are preferred because they are one of the cell types that give the highest energy per kilogram. As a result of chemical reactions in these cells, electrical energy is generated, which provides power to traction. Battery cells have safe operating ranges. In particular, the voltage and temperature values of the cells should be within some ranges. Otherwise, chemical reactions in the cells come to an uncontrollable point and undesirable fires, explosions or structural deformations may occur. In addition, since these cells are non linear systems, it is not easy to predict the changes in their internal structures as a result of their use. For this reason, it is a research area in itself to predict the energy remaining in the battery of an electric vehicle and therefore the range it can go to. In order to overcome such difficulties, there is a control unit that manages the battery and this module is called the battery management system. In this study, a battery management system will be developed to ensure the safety of the electric vehicle battery and has a new method to estimate the chemical structure of the batteries. The developed battery management system will measure voltage, current and temperature values in the battery and check whether the battery is at safe ranges. It will take the necessary actions to prevent these values get dangerous. In addition, the battery will drive auxiliary elements in battery pack such as contactors. It will send the measurements and calculations taken over the battery over the communication channels and work in harmony with the other components in the vehicle. The designed battery management system will be scalable and the big battery packets will be able to managed with different number of battery management system modules. There are many methods to analyze the chemical structures of batteries. The most important of these is electrochemical impedance spectroscopy. In this method, an alternative current is sent to a battery cell in the laboratory environment and the voltage change in the cell terminals is monitored. This voltage change analyzed in the frequency domain and an idea is obtained about the chemical internal structure of the cell. In spite of obtaining valuable information as a result of this method, the devices that do this analysis are expensive, heavy and stationary devices that can be used only in the laboratory environment. Within the scope of this study, it is aimed to integrate such an analysis method into designed battery management system. Thus, the tests performed in the laboratory will be able to performed on the vehicle also, and the accuracy will increase for battery management system calculations. Within the scope of this study, the hardware of a battery management system will be developed. After circuit schematic and printing circuit board design completed, circuit board will be produced and prototyping work will be done. Low level drivers, battery management system algorithms and electrochemical impedance analysis algorithms will be developed on this board. The developed product will be tested on a battery pack and measurements will be taken. Taken measurements will be used to express cell structure as an equivalent circuit model. Application areas that product can be used and future studies will be discussed.
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ÖgePaletli araçlar için otomatik transmisyonun dinamik modeli, kavrama parametre adaptasyonu ve kontrolü(Lisansüstü Eğitim Enstitüsü, 2022-02-17)Bu tez çalışmasında; paletli askeri araçlarda kullanılan otomatik transmisyonların vites değiştirme fonksiyonlarını gerçekleştirecek elektronik kontrol ünitesi kontrol algoritmaları tasarlanmıştır. Bu algoritmaların, transmisyonun dinamik modeli ile desteklenmesi sayesinde planet dişli sistemindeki kavramalarda herhangi bir hız ve basınç sensörü olmadan kontrol için gerekli değişkenler hesaplanmıştır. Kavramaların aşınması durumunda, kavrama parametreleri, yalnızca transmisyon giriş ve çıkış hızı sensörlerinden gelen bilgileri kullanan bir adaptasyon algoritması aracılığıyla kestirilmiştir. Bir yenilik olarak, atalet fazında dinamometredeki kalibrasyon işlemlerini kısaltacak, dayanıklı ve hassas kontrole olanak sağlayacak, dinamikleri doğrusal olmayan transmisyon sisteminde kullanılabilen, genetik algoritma ile optimize edilmiş bir PID kontrol tasarımı yapılmıştır. Tasarlanan dinamik model, uyarlama algoritması ve kontrolör, bir MATLAB/Simulink-Simscape güç aktarma sistemi simülasyon modeli üzerinde test edilmiştir.