Research On Labor Monitoring Method Based On Electromagnetic Tracker

Our country has a large number of population and also has a high proportion of birth-defect newborns. There are many reasons to affect the quality of newborns. The perinatal period is one of the most important factors. And the birth process is the most critical stage. The successful delivery is decided by the inter-coordination of the birth canal, force, psycho-mental factors of mater and the condition of fetal. So the labor monitoring is very necessary. Partogram is used for describing the birth process based on visual in the science of childbirth. And it is the primary reason to decide the mode of delivery and control the birth process. The important parameters of Partogram are the cervical dilatation and fetal head position. But the practical automatic measurement method of these parameters has not been offered for a long time. Due to the special condition of the anatomical position and measurement, the cervical dilatation and fetal head position are estimated through the vaginal touch by obstetricians. However the estimation through the digital examination has some disadvantages, such as the higher subjectivity and the lower accuracy. So it has a great value to research the accurate, objective and practical labor monitoring method to offer the real cervical dilatation and fetal head position.According to the requirement of the Partogram, this paper provides an automatic measurement method of the labor monitoring parameters based on the electromagnetic tracker. This paper researches the operational principle of the electromagnetic tracker and the distortion of the tracker suffered by the impact of the electromagnetic interference in the environment and bimetallism disturbance. And on these bases, this paper provides a calibration method of magnetic distortion according to the similar researches in home and abroad. This paper tests and verifies the practicability and reliability of the measurement method of the labor monitoring parameters presented by this paper, through designing the test experiment used the model of the pelvis and fetal head. And through designing the test experiments, this paper test the function of the medSAFE tracker and the distortion of the medSAFE tracker suffered by the impact of kinds of interference sources and verifies the effect of the calibration of the magnetic distortion used by the polynomial fitting method and modifier formula method. The experiments designed by this paper test and verify that the measuring range of the medSAFE tracker is reliable in the space of 100mm-400mm above the flat transmitter. And when the electromagnetic interference sources in the environment are placed 330mm above the tracker and the metal disturbance sources are not placed between the transmitter and receiver, the precision and accuracy of the medSAFE tracker can meet the demands of the measurement of the labor monitoring parameters. The experiments of the calibration methods of the magnetic distortion verify that 3 order polynomial fitting method is the better calibration method to correct the position errors produced by the magnetic distortion.In summary, the research on the labor monitoring method based on the electromagnetic tracker has the feasibility and practicability in this paper. And the measurement method and system designed by this paper can meet the demands of the measurement of the labor monitoring parameters in the clinical.