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Entry  Wed Sep 15 09:15:21 2021, Jiri Smetana, General, General, Actuation Feedback Model and Noise displacement_asd.pngservo.pngsystem_loop.mground_freq.txtground_xx.txt
    Reply  Thu Sep 16 10:02:47 2021, Jiri Smetana, General, General, Actuation Feedback Model and Noise DAC_voltage.png
       Reply  Fri Sep 24 11:02:41 2021, Koji, General, General, Actuation Feedback Model and Noise ground.m
Message ID: 29     Entry time: Fri Sep 24 11:02:41 2021     In reply to: 27
Author: Koji 
Type: General 
Category: General 
Subject: Actuation Feedback Model and Noise 

We had a meeting with the code open in ZOOM. Here are some points we discussed:

  • The code requires another file ground.m. It is attached here.
     
  • The phase of the bode plots were not wrapped. This can be fixed by applying the "PhaseWrapping" options as
    opts=bodeoptions('cstprefs');
    opts.PhaseWrapping = 'on';
    bode(A,opts)

     
  • We evaluated the open-loop transfer function of the system. For this purpose, we added the monitor point ('F') at the actuator and cut the loop there like:
    sys = connect(P, S, W, ADC, Winv, A2, DWinv, Dinv, DAC, DW, D, R, C, {'xg' 'nADC', 'nDAC', 'nd', 'nth'}, 'xt', {'F','VDAC'});
    OLTF=getLoopTransfer(sys(1),'F');
    figure(2)
    clf
    bode(OLTF,opts);
     
  • We played with the loopgain (Ga2). When Ga2 is a positive number, the loop was stable. We had to shift the low pass cut-off frequency from 10Hz to 12Hz to make the damping of the 2nd peak stable.
Attachment 1: ground.m  95 Bytes  Uploaded Fri Sep 24 12:03:39 2021  | Hide | Hide all
function [grnd] = ground(freq)
    grnd = 1e-7*(freq<1)+1e-7*(1-(freq<1))./(freq.^2+1e-50);
end
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