Modelling and control of a hemodialysis device

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Dr. Pataki Béla József
Department of Measurement and Information Systems

The occurrence of chronic renal disease and illnesses of heart and vascular system caused by that increases by 5-10% a year all over the world. According to certain estimations about one million people suffer from renal disease in Hungary and a part of them – around ten thousand people – need dialysis. Therefore, it is important to improve the dialysis machines. The development of a high quality dialysis apparatus requires the solution of many important, complex problems. One of the basic ones is the flow of the dialysis solution and to keep the parameters of the dialysis fluid on the designated level. As a result of expanded requirements the set domain of flow speed has changed from 300-800ml/min to wider as 100-800ml/min during treatments.

In my thesis I improved a hemodialysis machine's software component that is responsible for the dialysis fluid preparation, to make the machine meet the expanded requirements. I used Model-Based Design technology for development that is even more spread nowadays. In the first chapter the causes of chronic renal disease and the basic principles of dialysis machines are introduced. Furthermore, the outline of the dialysis fluid preparation process is also described here. In the second chapter a short overview about control systems and some controller types are presented. The choice of the appropriate development environment and the development process are also described in this chapter. In the remaining chapters of the thesis the practical problems and their solutions are presented. In the fourth section a software component that controls the dialysis flow and the so called balance chambers of the dialysis machine is introduced. This development is a result of a team work. In the next section I present my independent development, the so called conductivity controller that is responsible for the composition of the dialysis fluid by mixing concentrates with water in an adequate way. Having described my practical work at the end of both chapters I consider the results and compare them to the requirements. Finally in the sixth unit there is a summary of my full work.


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