Research On The Key Technology Of AC Electromagnetic Tracking System

Electromagnetic Tracking System has been widely used in many fields such as medical noninvasive system, targeting, reverse engineering and virtual reality.because it has the advantages of no radiation, non-line-of-sight obstacles, three-dimensional six degree of freedom positioning, operation conveniently and low cost. There are some flaws on the aspect of tracking range, speed and accuracy in already developed Electromagnetic Tracking System. They are required to be improved for meeting the business requirements.In this dissertation, several key technologies of the AC excitation tracking system were studied. Based on the theory of electromagnetic and Optimization algorithm, analog, digital circuits and with hardware, software technology, tracking experiment was successfully done by acquiring and analyzing AC excitation induced signal.Firstly, theory of AC Electromagnetic Tracking System was analyzed, and the advantage of AC excitation was pointed out. A new model of six degrees of freedom AC excitation tracking was established, mathematical function relationship between the induced voltage signal and parameters that illustrates three-dimensional six degrees of freedom position of the probe was derived, and Electromagnetic Tracking location equations were listed.Then, solving of higher order nonlinear equations was studied considering characteristics of Electromagnetic Tracking location equations. The solving effect of four algorithms were analyzed, Simulation and experiment showed that Levenberg-Marquardt algorithm can solve the complicated equations efficiently.Lastly, the tracking experiment platform was designed and constructed, optimal transmitting and receiving coils were designed, hardware circuit was designed, the program of lower computer based on single chip was complied. Using MATLAB software development platform to develop the PC software for signal acquisition, analysis and processing. Then the Tracking experiment was done. racking accuracy was analyzed and the main sources of error were found out, then the feasibility of system theory, model and algorithm was verified. Suggestions of reducing error and improving tracking accuracy were also made.