Demiryolu araçlarında kullanılan vakumlu tuvalet sistemleri için elektronik kontrolcü tasarımı
Electronic controller design for vacuum toilet systems in railway vehicles
Yazar: AYKUT ALTINTAŞ
Danışman: DOÇ. DR. MUHAMMED KÜRŞAD UÇAR
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik-Elektronik Mühendisliği Ana Bilim Dalı / Elektronik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
VTS'ler (Vakumlu tuvalet sistemleri), yolcu taşımacılığında kullanılan raylı sistem araçlarında yaygın olarak kullanılmaktadır. VTS'nin yaygınlaşmasının ana nedenlerinden biri, raylı sistem araçlarının tuvalet kabinlerinde oluşabilecek ve aracın yolcu kullanım alanına yayılabilecek kötü kokuları engellemektir. Ayrıca bir diğer neden ise, gerekli olan hijyen şartlarını sağlayarak tuvalet atıklarından bulaşabilecek enfeksiyonları önlemektir. Bu nedenlere ilave olarak meydana gelebilecek olumsuz çevresel etkileri engellemek için, insan kaynaklı atıklar, atık tankı adı verilen depolarda toplanır ve bu sayede atıkların raylarda korozyon oluşturması engellenir, dolaylı olarak atıklar nedeniyle temiz su kaynaklarının kirletilmesi ihtimali ortadan kaldırılır. Temiz su tüketim miktarları açısından VTS ile standart bir sifonlu tuvalet karşılaştırıldığında, her bir yıkama fonksiyonu döngüsünde VTS standart tuvalete göre %75-80 oranında daha az temiz su tüketmektedir. VTS üreticisi firmalar tarafından sağlanan verilere göre her bir yıkama döngüsünde yaklaşık olarak 0,5 litre temiz su tüketilmektedir. Günümüzde temiz su kaynaklarının hızlı bir şekilde tükendiği gözönüne alındığında, VTS'nin büyük oranda su tasarrufu sağlayabilir olma özelliği eşsizdir.
Bu tez çalışmasının kapsamında, Türkiye'de yolcu taşımacılığında kullanımda bulunan VTS'lere uygun, işletmeci ve demiryolu aracı üreten kurumlara yüksek maliyetler doğurmayacak, bakım/onarım ve imalat işlerini yürüten personellere gerekli kolaylıkları sağlayacak bir VTS elektronik kontrolcüsü tasarlamak amaçlanmıştır. Bu kapsamda bir elektronik kontrolcünün tasarımı yapılmış ve testleri gerçekleştirilmiştir. Testler iki aşamalı olarak ilk aşamada masaüstünde gerekli test ekipmanları kullanılarak, ikinci aşamada ise demiryolu aracı üzerinde mevcut bulunan VTS üzerinde gerçekleştirilmiştir.
Çalışmada ilk olarak elektronik kontrolcünün tasarımını oluşturmak için, yolcu taşımacılığında kullanılan raylı sistem araçlarının halihazırda kullanımda bulunan VTS'leri incelenmiş, bunun akabinde tasarımda kullanılacak programlama dili ve işlemci tipi, elektriksel ve fiziksel arayüz, kontrolcünün yürütmesi gereken fonksiyonlar, giriş-çıkış portlarının sayısı, maliyet gibi tasarım parametreleri belirlenmiştir. Bu kapsamda yapılan çalışmalar materyal ve yöntem bölümünde detaylı bir şekilde anlatılmıştır. Tasarım tamamlandıktan sonra ilk prototip ürün üretilerek masaüstü ve saha testleri yapılmıştır. Testleri tamamlanan elektronik kontrolcü, Türkiye'de yolcu taşımacılığında kullanılan yolcu vagonları ve dizel tren setlerinde bulunan VTS'lere uygun olarak tasarlanmış ve aktif olarak 2022 yılı içinde yolcu taşımacılığında kullanılan araçlarda kullanılmaya başlanmıştır. 
Üretilen elektronik kontrolcü, işletmeci kurum olan TCDDT A.Ş. (Türkiye Cumhuriyeti Devlet Demiryolları Taşımacılık A.Ş.) bünyesindeki dizel tren setlerine ait 124 adet VTS ünitesi ve yolcu vagonlarına ait yaklaşık 300 adet VTS ünitesinde yani toplamda 400 adetin üzerinde VTS ünitesinde kullanılabilmektedir. Tasarlanan elektronik kontrolcünün, gerekli görülen bazı fonksiyonların ve modüler olan donanımların uygun bir şekilde eklenip çıkarılmasıyla yani tasarımda gerekli revizyonların yapılmasıyla farklı tiplerdeki raylı sistem araçlarında bulunan farklı tip ve model VTS'lerde de kullanılabileceği öngörülmektedir.

Abstract:
Vacuum toilet systems which are working with clean water and pressurized air supply, are systems those control electropneumatic valves to perform operations such as siphon, flush etc. It is a system which designed to provide comfort and necessary hygiene conditions to the users/passengers. VTS needs 3 sources to perform its functions. These are respectively, direct current source, clean water and pressurized air.
Vacuum toilet systems are widely used in rail system vehicles which are used in passenger transportation. One of the aims of the dissemination of VTS is to prevent bad odors that may occur in the toilets of rail system vehicles which may spread to the interior of the vehicle. In addition, another aim is to prevent infections that can be transmitted from toilet waste by providing hygiene conditions. In addition to these purposes, in order to prevent negative environmental effects that may occur, human-made wastes are collected in warehouses called waste tanks, thus preventing the wastes from forming corrosion on the rails, and eliminating the possibility of polluting clean water resources When comparing the VTS with a standard flush toilet in terms of clean water consumption amounts, the VTS consumes 75-80% less clean water than a standard toilet from each flushing cycle. 
Within the scope of this thesis, a cost-effective electronic controller that can be used in VTS of rail system vehicles used in passenger transportation has been designed and tested. In the study, firstly, to design the electronic controller, the VTS of the railway vehicles used in passenger transportation were examined, and the design parameters such as the programming language and processor type to be used in the design, the electrical and physical interface, the functions that the controller should perform, the number of input-output ports, and the cost were determined. Afterwards, desktop and on-board tests of the first prototype product designed were carried out. The electronic controller, whose tests have been completed, has been designed for the VTS in passenger wagons and diesel train sets used in passenger transportation in Turkey and has been started to be actively used in operation in 2022. The controller, which is designed, can be used in 124 VTS units which belong to diesel train sets and approximately 300 VTS units which belong to passenger wagons which are under service of the operating company, TCDD Tasimacilik.
In the thesis section of source research, developments and studies which related to conventional toilets and vacuum toilet systems used in passenger transportation from the beginning of the 1900s to the present, are shared. The reasons why VTSs are preferred over conventional toilets are explained. With the development and spread of technologies such as the internet of things, project proposals regarding the management of VTSs in highly populated areas from a control center and the efficient execution of public services are shared. VTSs specially developed for the elderly, disabled and sick individuals are exemplified. Thanks to the developing technology, it has been exemplified that VTSs can be used in the early diagnosis of diseases in the healthcare field. A project where comfort conditions can be adjusted individually in VTSs which were developed for elderly and disable individuals has been shared.
In the material and method section of the thesis, the characteristics of the microcontroller to be used in the electronic controller, details of the circuit drawing platform and the code development environment and why they were preferred, are explained. In the system components subsection, equipments such as toilet module, electrical panel, clean/wastewater system in VTS are explained and shared with their visuals In the working fundamental subsection, firstly how VTS gets the pressurized air source which provided by the railway vehicle's air compressor and its pneumatic diagram are shared. The placement levels of the level sensors in the clean water and waste tanks are indicated in the tanks. It is explained how the electronic controller evaluates the received information from these sensors and what actions the controller does with the information. The controls that need to be done by the VTS controller for VTS to be ready for operation, are shared in detail. In the functions of VTS subsection, it is explained how functions such as washing/vacuum, bidet, faucet work and how user/passenger demand is created. Working-time diagrams of the 6 electropneumatic valves operated in overflow and washing functions that recorded by the help of a logic analyzer and how these functions are carried out, are explained in detail.
In the hardware architecture subsection, the circuit structures which used in VTS electronic controller are explained in detail. These are the voltage regulation circuit used to regulate supply voltage to the appropriate level for the microcontroller, the input port circuit structure which used for the signals produced by the peripheral units as logic 0 or 1, the temperature sensor and pressure transmitter's interface to the electronic controller, the circuit structure which drives the electropneumatic valves and finally circuit structure which drives the diagnostic leds. In the input/output signals of the controller subsection, the electrical interface between the electronic controller and the peripheral units and the signals available in the interface are explained in detail. Also, in the same subsection, the data of the temperature sensor which used to prevent freezing in the liquid installation and the evaluation of this data by the controller are shared. By sharing the data conversion table of the pressure value which read from the ADC (Analog digital converter) module of the microcontroller, the effect of these pressure values on the functions of the VTS, is explained in detail. How the lower limit and upper limit of the pressure values which were determined for the VTS and how the system works under the influence of these values are examined in detail. 
In the software architecture subsection, pseudo-codes of the software which is run by the VTS electronic controller, are shared and these codes explained in detail. In this section, initialization paremeters of the microcontroller, the settings of the timer functions, the settings of the analog-digital conversion module are shared and explained in detail. Timer functions are used to drive electropneumatic valves of the VTS and to generate diagnostic data. The analog-digital conversion module is used in pressure control processes in the VTS electronic controller. Also, in this section, information about the control function of the user/passenger buttons, the control of the peripheral units related to the anti-freeze function, and finally software for the washing and overflow functions are given in detail. 
In the research findings section, desktop tests results for the electronic controller which is produced by the help of the circuit drawing platform are given in detail. The test box, which is prepared for test operations, has switches to test the input signals, a potentiometer to simulate analog pressure value as voltage value and finally 8 led indicators to see the outputs of the electronic controller. A logic analyzer is also placed inside the test box to see the run-time diagrams of the electropneumatic valves. After the completion of desktop tests, the electronic controller is mounted of the VTS electric panel, and afterwards on-board tests are done, and it was shown that the VTS is ready for passenger service. In addition, in this section, the necessary procedures to mount the electronic controller to the electrical panel are explained in detail. 
In the discussion and conclusion section, the purposes of designing a new electronic controller and which railway vehicles it is suitable for are explained. The advantages and disadvantages of the electronic controller are also given in detail in this section. The improvement works that can be done for the controller, which was designed for this thesis, are briefly explained.