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What determines maximum bandwidth?

Steve Ressler
Intellectual 270 points

Hi,

I'm curious what determines the maximum possible value of gMotorVars.SpinTAC.PosCtlBw_radps before gMotorVars.SpinTAC.PosCtlErrorID reports saturation? I'm asking because I have projects on different machines (same motor and hardware) and one allows approximately double the bandwidth before saturating, and I can figure out why this is happening.

Thanks,

Steve

  • 0
    Guru 12800 points

    Steve,

    The maximum bandwidth is based primarily on the sample time.  

    For velocity control systems the maximum bandwidth is determined by this expression (from spintac_velocity.h):

    (0.2) / (ST_SAMPLE_TIME)

    For position control systems the maximum bandwidth is determines by this expression (from spintac_position.h):

    (0.1) / (ST_SAMPLE_TIME)

    So velocity control systems can have the bandwidth set twice as high as position control systems.  Are you using different projects on these different machines?

  • 0 in reply to Adam D. Reynolds
    Intellectual 270 points

    Thanks Adam, this is what I needed to know. I had different values for USER_PWM_FREQ_kHz between the two systems.

    -Steve