Optimal Design And Control System Development Of Hemodialysis Machine

The number of patients with end-stage renal disease in China is large and increasing year by year.Hemodialysis is a relatively mature replacement therapy,which can alleviate the symptoms and prolong the life of patients.At present,the market of hemodialysis machine in our country is mainly occupied by the imported brands.Researching and developing high-quality and low-priced hemodialysis machine is not only the pursuit of medical enterprises,but also the advancing of medical science and technology.Therefore,relevant research work has been done in this thesis.First of all,according to the new demand and higher requirements,the original prototype is optimized in consideration of the integrity,security and accuracy.The extracorporeal circulation system and dialysate preparation system are perfected.In the extracorporeal circulation system,the blood pump was replaced,the pressure measurement point is increased,the liquid level monitoring of venous kettle is added,and the structure of the vein clamp is redesigned.In the dialysate preparation system,the flow control module,the ultrafiltration module,the temperature control module and the conductivity module have been improved to varying degrees.In addition to the structure optimization,this paper also analyzes the control system of the specific requirements,works out a whole design of the embedded control system,including the hardware and software systems,and determines the structure of the hardware and software systems.And then makes a preliminary configuration of the FreeRTOS real-time operating system applied in the software system.Secondly,the architecture of hardware system is constructed by integration and modularity.The application circuit of communication circuit,sensor measurement circuit,drive circuit and feedback circuit are analyzed and designed in detail.For the sensor measurement circuit,the experiment is designed to calibrate the sensor and its measurement circuit,ensuring the accuracy requirement of the measurement system.Furthermore,an embedded software control system based on FreeRTOS real-time operating system is designed.The system divides the overall control system requirements into different interrelated but independent tasks according to the needs,which perform their respective functions,therefore achieving the control objectives.Information synchronization between tasks is achieved by semaphore,queue and task notification,which improves the real-time and security of the system.Finally,the task priority,scheduling mode and the process of every task are designed.On the basis of the optimization of the liquid structure,the design and development of the control system for a new type of hemodialysis machine have been completed in this paper.The experimental test according to the industry standard shows that the prototype is fully qualified in flow control,ultrafiltration control,temperature control,electrical conductivity control and so on.