眼压测量中电磁压力控制系统的设计

Design of an Electromagnetic Pressure Control System in Intraocular Pressure Measurement

目的:本文研究眼压自动测量中利用电磁驱动的压力控制系统。压力控制的精度直接影响眼压测量值的正确性,故要求能实现压力精确闭环控制。方法:根据眼压测量的实际需求,通过数值计算和ANSYS仿真相结合的方法,得到电磁驱动系统的结构参数和电磁参数;通过单片机利用I2C总线和模数、数模转换,通过数字量精确控制驱动电流的大小以实现压力的闭环控制。结果:由实验测量结果可知,该电磁压力控制系统的压力范围为0N～0.48982N,精度为0.00058N,驱动电流控制的误差平均在1%左右,且在行程不变时,电磁力和激励电流呈较好的线性关系。结论:该电磁压力控制系统实现了压力的闭环控制,可控压力范围和控制精度都符合Goldmann压平眼压计的标准,为眼压自动测量仪的研制打下了基础。

Objective： This paper studied the electromagnetic-driven pressure control system in the automatic measurement of intraocular pressure （IOP）. The accuracy of pressure control directly impacts on the accuracy oflOP measurements, so it calls for precise pressure to achieve closed-loop control. Methods- According to the actual needs of IOP measuring, we got the structural and electromagnetic parameters of the electromagnetic drive system by combining the methods of numerical calcula- tion and ANSYS simulation. Using the I2C bus and digital-analog conversion, the microcontroller module controlled the drive current digitally and precisely in order to achieve closed-loop control of pressure. Results： The experimental results showed that in the electromagnetic pressure control system, the pressure range was 0 N- 0.48982 N, the accuracy 0.00058 N, the drive current control error about 1% on average. Besides, the electromagnetic force and the excitation current showed a good linear relationship in the same stroke. Conclusions： The electromagnetic pressure control system achieved a good result in closed-loop control of pressure. The control pressure range and control accuracy were in line with the standard of Goldmann applanation tonometer. According to the results, this study laid the foundation for the further development of IOP automatical- ly measuring instruments.