Research And Implementation Of The Electromagnetic Locating System

Considering the locating accuracy, system stability, operability and cost of the Computer Assisted Orthopedic Surgery (CAOS), and the complexity and variability in orthopedic surgery, this system proposed an electromagnetic locating method.According to the Biot - Savart law the AC coils were used as the emission source and based on the law of electromagnetic induction the receiver coils produced a corresponding induced electromotive force. The spatial distribution of the magnetic field was get by calculating. The equations that contained the position and orientation information of the target were derived. The optimization algorithm was used to solve the nonlinear equations. Therefor an stable and real-time locating method was obtained.The locating system consisted of the signal emission, signal reception, signal extraction, calculator and display of the result. The distribution of the magnetic dipole model was established and calculated by the LM algorithm. Simulation were carried out to verify the system feasibility and calculate the specific parameters of the signal emission. According to the need of this system the transmitter and receiver circuits were designed while the method of result fitting and system parameter calibration was took to further improve the accuracy of the system. VC + + software was used to develop the calculating and display part of the sysetm. Experiment of locating and tracking the target showed the locating accuracy of the system: the average position error was less than 1mm and the average direction error was less than 1°.The accuracy of the electromagnetic locating system was in the mm level. This system had small size, low price and was less susceptible to outside interference. In addition to the application in the Computer Assisted Orthopedic Surgery , electromagnetic locating system could be widely used in military targeting, virtual reality, remote drilling and so on.