The extraction technology of weak coupling AC signal in an electromagnetic localization system

In the program of bone surgery robot, we employ an electromagnetic method to locate the position of surgical instruments and surgical sites. In this processing, the key part is to extract the coupling voltage signals that are sensed by the sensing coils as accurately as possible, because it will affect the precision of location directly. However, in the real system, these coupling voltage signals are very weak and be drowned in noises. In this paper, we propose three methods to extract this signal accurately, which are phase lock amplifier, function fitting and Fast Fourier Transformation (FFT). Also we make theoretical analysis and emulation for each method, and show their experimental results. After sedulous comparison, we conclude function fitting is the most suitable method for this system.