I measured the open-loop transfer function of the magnetic levitation system.
The schematic block diagram for this measurement is the following:
I injected a signal at a level of 20mV between two preamplifiers, and the corresponding open-loop
transfer function is given by B/A. I took a picture of the resulting measurement, because
I encountered some difficulties to save the data to the computer via the wireless network.
The bode plots for the transfer function shown on the screen is the following:
I am puzzled with the zero near 10 Hz. I think it should come from the mechanical response function, because there is no zero in the transfer functions
of the preamplifer and the coil itself. I am not sure at the moment.
The corresponding configuration of the levitated magnet is