Wire Diameter Online Detection And Control Technology For Absorbable Sutures

Chitosan-collagen absorbable suture has been widely used in the surgical operation because of its strong plasticity,good biocompatibility and biodegradability.In the process of suture forming and winding,measuring and controlling the suture diameter are the preconditions for holding diameter even and tensile strength constant.Due to the lack of key technology of spinning process,the spraying speed of the traditional spinning process is not easy to be controlled,so it leads that the absorbable suture diameter is uneven.this will seriously effect the popularization and application.The traditional measurement is offline and performed on the experiment table,it has long measurement cycle and slow speed and it can not achieve the closed-loop control.In this paper,a measurement and control technology of absorbable suture diameter is presented,it achieves the closed-loop control and online detection of spinning formation and enhances the accuracy of the control system,it ensures that the diameter of the chitosan-collagen absorbable suture is uniform.The diameter control system of absorbable suture in the spinning process includes three parts which are the core control module,the spraying device and the diameter detection module.The diameter detection module collects the optical intensity information from linear array CCD image sensor TCD1209D which is drivered by 32 bit ARM Cortex-M3 core microcontroller STM32F103ZET6.The collected electrical signal is sent to on-chip AD converter after the signal conditioning,then the data is processed by using the method of binarization image segmentation based on genetic algorithm.After the diameter calculation,the measurement value of absorbable suture is obtained and the online detection is realized.A spraying device based on reverse series double hydraulic cylinder is designed.The measurement value of the chitosan-collagen absorbable suture obtained by diameter detection module is sent to the core control module based on STM32F103ZET6.Using the improved generalized predictive control algorithm to control the speed of the DC servo motor in the spraying device,then adjusting the spraying speed of nozzle to get the nascent suture whose diameter is as same as the setting value of absorbable suture.After a series of technological processes,the nascent suture becomes the final absorbable suture.It achieves the diameter closed-loop control of chitosan-collagen absorbable suture.The measurement and control technology of absorbable suture diameter realizes the non-contact online measurement and closed-loop control in spinning process.The diameter of absorbable suture reaches the People’s Republic of China pharmaceutical industry standard YY1116-2010 "Absorbable Surgical Suture".The system accuracy reached 2%,the diameter of final absorbable suture is even.This paper has an important significance to improve the domestic medical level and the scientific research on the suture line.