2.737 Project - Fall '97

Vibration Isolation Platform

This final class project involved the design of a control system for a single axis vibration isolation platform. The physical system consisted of a speaker cons driver and a geophone sensor. The speaker cone and the geosensor were connected to a computer via amplifiers and A/D and D/A boards. A digital control system inside the computer took the sensor input and calculated appropriate commands to the cone driver. The section below gives a brief look at the system.

    A view of the speaker and geophone platform.
     This is the whole experimental setup - also shown are the power amp and the computer with an A/D board.
    This is a frequency response plot of the speaker & geophone platform. Note the effect of the sensor frequency cutoff at 14 Hz .
    A MATLAB model of the plant, used in modeling the system. High frequency poles were neglected.
    A bode plot of the controller I designed to compensate the system.
    A finished plant with feedback control. Hmmm... I think this particular plot has an extra pole at 1kHz. Oh well, I tried several controller configurations. This one had better attenuation at higher frequencies, but lower phase margin. It was somewhat unstable toward low frequency disturbances, but rejected high frequency noise quite well.
    The final product - the bottom oscilloscope trace shows disturbances of the cone with and withou the control system operating. Note that the disturbances are severely attenuated if the system is on.

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