Research On High Precision Full Closed Loop Injection Pump Technology

In modern medicine,the syringe pump is an infusion device that can accurately control the flow rate and is widely used in the field of medical care,such as EICU wards,pediatrics,gynecology,and operating rooms.However,the FDA issued a warning on August 25,2016,stating: "When the flow rate is less than 5 m L per hour,especially when the flow rate is less than 0.5 m L per hour,the syringe pump may cause serious clinical problems caused by insufficient flow discontinuities.Consequences that result in delays in treatment,excessive infusions,or infusions."This topic focus on the FDA issuing warning to medical service providers,it takes the injection pumps as the research object,and uses SOILDWOERKS to complete the mechanical structure design of full-closed-loop injection pump experimental platform.The system mechanical structure design mainly includes the design of the reducer,the design of the injection mechanism,and the design of the screw nut mechanism.According to the fullclosed-loop control theory and subdivision control technology of the stepper motor,a fully closed-loop injection pump experimental platform is designed with STM8S003F3 as the main control chip.The entire experimental platform utilizes a double closed-loop,one is the semi-closed-loop control using photoelectric encoder signal as feedback signal,and the other is the full-closed-loop control of the capacitive sensor signal as the feedback signal.Integrate the STM32F107 chip based on the UCOS-III real-time operating system,designing a closed loop injection pump experiment platform touch screen control module which makes the operation easier.At the same time,the full-closed-loop regulation of the full-closed-loop injection pump experiment platform was realized by using incremental PID control algorithm.In order to investigate and analyze the causes of the discontinuity caused by injection pump injection,the open-loop control,closed-loop control,and full-closed-loop control tests were performed on specification of 1 ml,2 ml,and 5 ml,respectively.The experimental data analysis results show that the factors affecting the injection pump discontinuity is the stepper motor control accuracy and mechanical structure accuracy.For the influencing factors of the control precision of the stepping motor,we have proved through experiments that a stepping motor with a small step angle should be used in the design of the injection pump.At the same time,in order to avoid the loss of the stepping motor,an encoder or Semi-closed loop control feedback should be used.The accuracy of the mechanical structure mainly includes the processing accuracy and the assembly accuracy.Through the analysis of the experimental data,it can be seen that the introduction of the mechanical error is a major factor in the injection pump injection discontinuity.The full-closed loop control of stepper motor can effectively reduce the impact of mechanical errors on injection continuity.