M. Barton, D. Bridges, J. Kissel

These are the beginnings of the aLIGO Production Matlab Dynamical Model of the Output Mode Cleaner Suspension (OMCS). The last (known) attempt at this was during the Final Design Review: T080138, but the OMC breadboard suspension design has changed dramatically since (see the aWiki for details). Mark has brushed off the dust and greased the wheels of the core model components, 
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/ssmake2MBf.m
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/symbexport2full.m,
and Derek and I have gathered enough information from his SolidWorks Assembly (D0900295) for me to create new parameter files:
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/omcsopt_metal.m
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/omcsopt_glass.m

With the usual-style wrapper function,
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/generate_Double_Model_Production.m,
I've compared all three parameter sets (where omcsopt_doublep.m is the FDR version from T080138), and attached the TOP to TOP transfer functions. Details of the differences in parameters are listed below, but the major differences are
(1) Bug fix with moments of inertia (a mix up between SolidWorks and Euler Suspension coordinate systems that's now resolved)
(2) M1 to M2 wire length is shorter by 3 [cm]
(3) The suspension break-off point (the "d2") of the breadboard increased from 3 [mm] to 40 [mm]
(4) We're now correctly accounting for the imperfect flexing of the wires (i.e. turned on the flexure correction)
With these differences, the rotational dynamics are totally different (modes frequencies are all shuffled around), but not nearly as bad as I thought it would be because of the shorter wires and larger d2 (with which I would expect *higher* mode frequencies). I'll be interested to see these parameters plugged back into the full Mathematica model to check out the mode shapes.

ANYWAYS, 
Step 2 is to get some data once we've built up one of these suckers, and compare. Then we'll do the usual compare and contrast to see if the model's in any way accurate*.
Step 3 is to develop the whole suite of software that we have for the other suspensions, i.e. transfer function comparisons, actuation range calculations, residual ground estimates, etc. 
Step 4 is to design damping loops (though not much thought is needed, just a little gain tuning on the basic loops should be fine for now).

... but at least we're done with Step 1 finally!

-----------------

* Note that there's very little difference in dynamics between the glass and metal parameter set, but I didn't know that before getting started, so I created both. Once we get a few measurements under our belt, if we see that the assembly variance outweighs the dynamical variance, we can toss one of the sets in the trash and move on.

Detailed breakdown of parameter differences:

    'Fields'     'omcsopt_doublep'    'omcsopt_metal'    'Abs. Difference'    'Rel. Difference [%]'
    'm2'        [          6.895]    [        6.971]    [          0.076]    '1.1%'               
    'I2x'       [          0.139]    [       0.0152]    [        -0.1238]    '-89.1%'             
    'I2y'       [         0.0164]    [        0.148]    [         0.1316]    '802%'               
    'I2z'       [           0.15]    [        0.136]    [         -0.014]    '-9.33%'             
    'l1'        [           0.25]    [       0.2496]    [        -0.0004]    '-0.16%'             
    'l2'        [           0.25]    [         0.22]    [          -0.03]    '-12%'               
    'r2'        [       0.000102]    [    0.0001005]    [       -1.5e-06]    '-1.47%'             
    'Y1'        [       2.12e+11]    [    2.119e+11]    [     -100000000]    '-0.0472%'           
    'Y2'        [       2.12e+11]    [    2.119e+11]    [     -100000000]    '-0.0472%'           
    'ufc1'      [           2.38]    [         2.34]    [          -0.04]    '-1.68%'             
    'stage2'    [              0]    [            1]    [              1]    'Inf%'               
    'd0'        [         0.0018]    [        0.001]    [        -0.0008]    '-44.4%'             
    'd1'        [         0.0015]    [        0.001]    [        -0.0005]    '-33.3%'             
    'd2'        [          0.003]    [       0.0402]    [         0.0372]    '1.24e+03%'   


    'Parameter'                      'omcsopt_metal'    'omcsopt_glass'    'Abs. Difference'    'Rel. Difference [%]'
    'm2'                             [        6.971]    [        6.916]    [         -0.055]    '-0.789%'            
    'I2x'                            [       0.0152]    [       0.0142]    [         -0.001]    '-6.58%'             
    'I2y'                            [        0.148]    [        0.132]    [         -0.016]    '-10.8%'             
    'I2z'                            [        0.136]    [        0.122]    [         -0.014]    '-10.3%'             
    'd2'                             [       0.0402]    [       0.0391]    [        -0.0011]    '-2.74%'             
    'flex1'                          [    0.0018715]    [    0.0018768]    [     5.3147e-06]    '0.284%'             
    'flex2'                          [   0.00099653]    [    0.0010005]    [     3.9546e-06]    '0.397%'             
    'kc2'                            [       624.29]    [       619.36]    [        -4.9255]    '-0.789%'            
    'tl2'                            [       0.2612]    [       0.2601]    [        -0.0011]    '-0.421%'            
    'l_suspoint_to_centreofoptic'    [       0.5118]    [       0.5107]    [        -0.0011]    '-0.215%'


Also scripts and functions are committed to 
${SusSVN}/sus/trunk/Common/MatlabTools/DoubleModel_Production/
as of this entry. Svn up and away!