RESUMO
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 of IOP 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 calculation and ANSYS simulation.Using the FC 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 automatically measuring instruments.