Design And Realization Of Constant Pressure Insufflator Based On PID Control

Since the birth of minimally invasive surgery,the endoscopic system has been widely used in the medical field.The role of the insufflator is to inject CO2 gas into the surgical area of the patient to expand the space of the pneumoperitoneum to maintain a good surgical field of vision.At present,there are a considerable number of insufflator that they only can establish pneumoperitoneum.Moreover,due to the relatively simple structure of most insufflator,their ability to maintain pneumoperitoneum balance is very poor,even in some cases not very good to maintain pneumoperitoneum.Based on the analysis of the performance defects of the traditional insufflator,this thesist designs an improved insufflator with constant pressure.This thesist firstly improves the structure of the gas circuit from the structure of the traditional gas circuit.The traditional gas circuit is a single pipeline into the abdominal cavity of the human body.The insufflator designed in this thesist has an additional air path that can realize real-time abdominal pressure.Therefore,its structure changed from the traditional non-real-time abdominal pressure sample to real-time data sample,so the sensitivity and response speed of the insufflator were significantly accelerated.Secondly,the hardware system was formed by the core of MCU and other hardware,such as reducing valve,flow valve and pressure sensor.In order to ensure the safety of the system,the system places the data communication and control functions on two separate PCB,and both of the boards'MCU is Atmel's Atmeg2560 8Bit MCU.The main task of the control board is to realize the control algorithm such as the establishment and balance of pneumoperitoneum.The main task of the communication board is to connect the HMI and control system.The core of the HMI module is the i.mx 6 dll,a chip which has double coretex-a9 kernel from Fresscale.HMI software is developed on Windows Embedded Compact 2013 platform.The software provides simple and easy operation interface for insufflator.This thesist using the PID control algorithm to achieve a stability pneumoperitoneum.After continuous debugging and revision,the system now works stable.The pressure accuracy of insufflator can be less than 0.5mmHg,which is higher than the normal insufflator within 4mmHg.The constant pressure insufflator can achieve a fluctuation amplitude less than 0.5mmHg fluctuation amplitude,better than the general insufflator in the dynamic adjustment range of 4mmHg.In addition,the system realizes the function of real-time smoke extraction and can get a clearer endoscope space,the safer operation and less physical injury to patients and perioperative personnel.