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Entry  Thu Apr 18 22:35:23 2019, gautam, Update, SUS, ETMY actuator diagnosis  
    Reply  Fri Apr 19 11:36:23 2019, gautam, Update, SUS, No consistent solution for output matrix 
       Reply  Fri Apr 19 15:13:38 2019, rana, Update, SUS, No consistent solution for output matrix 
          Reply  Fri Apr 19 16:19:42 2019, gautam, Update, SUS, Actuation matrix still not orthogonal 
             Reply  Fri Apr 19 19:22:15 2019, rana, Update, SUS, Actuation matrix still not orthogonal 
    Reply  Mon Apr 22 22:43:15 2019, gautam, Update, SUS, ETMY sensor diagnosis  ETMY_sensorSpectra_consolidated.pdf
       Reply  Thu Apr 25 00:30:45 2019, gautam, Update, SUS, ETMY BR mode  ETMY_sensorSpectra_BRmode.pdfETMY_sensorSpectra_BRmode.pdfETMX_sensorSpectra_BRmode.pdfIMG_5993.JPG
Message ID: 14558     Entry time: Fri Apr 19 16:19:42 2019     In reply to: 14557     Reply to this: 14559
Author: gautam 
Type: Update 
Category: SUS 
Subject: Actuation matrix still not orthogonal 

I repeated the exercise from yesterday, this time driving the butterfly mode [+1 -1 -1 +1] and adding the tuned PIT and YAW vectors from yesterday to it to minimize appearance in the Oplev error signals. 

The measured output matrix is \begin{bmatrix} 0.98 & 0.64 & 1.5 & 1.037 \\ 0.96 & 1.12 & -0.5 & -0.998 \\ 1.04 & -1.12 & 0.5 & -1.002 \\ 1.02 & -0.64 & -1.5 & 0.963 \end{bmatrix}, where rows are the coils in the order [UL,UR,LL,LR] and columns are the DOFs in the order [POS,PIT,YAW,Butterfly]. The conclusions from my previous elog still hold though - the orthogonality between PIT and YAW is poor, so this output matrix cannot be realized by a simple gain scaling of the coil output gains. The "adjustment matrix", i.e. the 4x4 matrix that we must multiply the "ideal" output matrix by to get the measured output matrix has a condition number of 134 (1 is a good condition number, signifies closeness to the identity matrix). 

Quote:

let us have 3 by 4, nevermore

so that the number of columns is no less

and no more

than the number of rows

so that forevermore we live as 4 by 4

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