7. Analog Sensor Studies

 

        Along with the DCOPS optical sensor testing, we tested a prototype CMS

Z transfer (-X survey) between a reference MAB surface and the Transfer plate

system (ET1/ES1 mechanical link), a dual axis inclinometer on the Transfer

plate (Applied Geomechanics 900) to define its orientation with respect to

gravity (Q,F), plus a prototype CMS R transfer (+Y survey) between the

Transfer plate system and a mock ME2/2 outer boundary (CSC panel) plus

a prototype R connection between a mock ME2/2 inner boundary and a

ME2/1 outer boundary. ME2/2 was simulated by a 50 mm wide, 11.2 m

long strip of CSC panel. It may not be a good representation of a CSC

assembly because of thermal flexure and free expansion.

           The MAB Z connection was a distance measurement between an

OMRON Z4MW40 laser distance sensor and a MAB surface about 45 mm apart.

The sensor was mounted on the end of a  1168 mm (1175 mm july-sept)

Aluminum tube. The other end of the tube contacted a spring loaded potentiometer

LCP8-10 mounted on the Transfer plate and measuring the gap to the tube.

There were two temperature sensors T1 and T2 on the two ends of the tube.

They tracked each other extremely well and provided temperature monitoring

to 0.1 deg K. 

            The R connections were done with wire extension potentiometers

LPXA-2 (50 mm stroke).  All of these devices are voltage output devices.

             Finally temperatures around the setup were measured with Analog

Devices AD592 current source devices (1 mamp/deg K) which terminated

on voltage dividers near the DAQ giving 10 mv/deg K.  All of the sensors

were read out as analog voltages by an HP 34970A data acquisition/switch

system which scanned the sensors through an ADC to a serial port of

the DAQ computer. It also provided timing (gating) of the lasers in DCOPS

measurements.  With the low pass filtering installed (determined by tests

at Fermilab), we were able to limit noise effects (ADC fluctuations) on our

distributed system (15 m lines) to ± 0. 75 mv.

        We had calibrated all these sensors at Fermilab and the results are

available @http://home.fnal.gov/~leer/calibration/ISR_Analog_Sensor.

The effective calibration of these sensors is given in the following Table MM.

       The Transfer plate inclinometers are (x = q, y = f). The Z4MW40 is the laser

distance sensor to the MAB, ZLCP8-10 is the gap potentiometer between the

Transfer plate and the Z tube, RLXPA-2-1 is the R transfer potentiometer

between ME1/2 and ME2/2 CSCs, and RLPA2-2 is the R transfer potentiometer

between the Transfer plate and the ME2/2 CSC.

        Typical temperature coefficients are (for inclinometers) span +0.03%/deg C

and zero 10-20 arc seconds/deg C, for LPX2A potentiometers +0.03%/deg C,

for LCP8-10 potentiometer  400 ppm/deg C, for Z4MW40 laser  distance sensor

.03%Full Scale/deg C (for sensor and for amplifier). For our three test periods

in I4, the temperature varied at most 1.5-2 deg C overall and in each period.

All the analog sensors were referenced by a very stable 12 V  DC power supply.

 

 

Table MM. Analog Sensor Conversions:

 

qx(tilt)(arc deg) = 10.4739Vx – 0.0963Vx2 – 0.1714Vx3 + 0.0025Vx4 + 0.0026Vx5

 

qy(tilt)(arc deg) = 10.5002Vx + 0.1549Vx2 – 0.1942Vx3 - 0.0037Vx4 + 0.0062Vx5

 

ZZ4mW40 (mm) = (VZ4M + 16.180)/(0.4038) + ZFace position

 

ZLCP8-10(mm) = (VLCP8)/(1.0987) + Z free point position

 

RLX-PA-2-1 (mm) = (11.928 – (VLX-PA-2-1))/(0.2202) + R Zero Extension     (ME2/1-ME2/2)

 

RLX-PA-2-2 (mm) = (11.928 – (VLX-PA-2-2))/(0.2188) + R Zero Extension       (ME2/2-Tr Plate)

 

Tn (deg K) = (VTn – offset(n))*100  where o(n) = 0.007, 0.032, 0.034, 0.032,

 

0.033,0.035  for n = 1,..,6

 

 

    They are all very linear except the inclinometers which have some polynomial

corrections for fluid vessel shape. All sensors have small thermal coefficients.

        Periodically we did special “burst” runs of rapid multi measurements of

analog sensors only. These define the short term (instantaneous) resolution of these

sensors.  These runs are time stamped, so they can be used for long term

studies. Tracking the burst measurements throughout the running periods

provided a redundant  high statistics test on long term stability/drift to compare

to normal data samples. Typically, we took two hundred measurements in a burst run.

For short term resolution estimates we took the worst standard deviations found in any

Run as the guaranteed short term resolutions. The instantaneous resolution results are

given in the following Table NN.

 

Table NN - Short Term Resolutions:     

 

sQx(Xtilt)= sfy (Ytilt) = 0.52 mv = 19.54 arc sec    12 V Analog Reference  s = 0.567 mv

    

                          

sZ4M-MAB = 0.778 mv = 1.93 mm         sLCP8-10 Z-Trans Plate = 0.517 mv = 0.5 mm

 

 

sME2/2-Trans Plate R= 0.523 mv = 2.4 mm     sME2/2-ME2/1  R  =1.039 mv = 4.7 mm

 

 

AD592 Temperature sensors             s = 1.032 mv = 0.10 deg K  (typical 0.05 deg K)

 

 

 

       We have taken measurements of the analog sensors each time we took any

measurements (any laser combination) of the DCOPS sensor lines. Typically,

eight analog measurements are made in a DCOPS cluster measurement. These

measurements were used in each test period (about one week) to determine

Intermediate sensor resolutions (with/without thermal drift corrections). All

sensors show some small thermal dependence. Also our mechanical rulers; 

the Z tube and the ME2/2 CSC strip expand/contract in di urnal thermal cycling. 

The Raw analog (no thermal drift corrections) standard deviations of measurements

for the three test periods are given in Table PP. below:

 

Table PP - Intermediate Term Resolutions: (one run period ~week)

 

Use data from normal cluster runs (cycles 8 measurements every 15 min); no

corrections, all points are raw data (LM302 off – 4 measurements /cycle):

 

 Period                      sXtilt (Q)         sYtilt (F)             Z4M-MAB          12V Ref  

 

June            s =   116.75 arc sec      58.31 arc sec        18.04  mm        1.06 mv

                                (3.11 mv)         (1.55 mv)             (7.25 mv) *

 

July/Aug     s =     97.23 arc sec       58.31 arc sec        32.22 mm         0.50 mv

                                (2.59 mv)         (1.55 mv)             (12.95 mv)

 

Sept             s =     97.23 arc sec      19.56 arc sec        46.19 mm         4.17 mv

                                (2.59 mv)            (0.52mv)           (59.58 mv)    

 

 

Period                 LCP8-10 (ZTP)      ME2/2-TP R          ME2/2 – ME2/1 R

 

 

June            s =  23.60  mm              14.03  mm             68.25  mm**

                          (25.90 mv)              (3.07 mv)             (15.03 mv)

 

July/Aug     s = 28.80 mm                  18.92 mm           44.70  mm**

                         (31.60 mv)                (4.14 mv)           (9.843 mv)

 

Sept            s =  11.80  mm                14.21  mm           75.29  mm**    

                          (12.95 mv)               (3.11 mv)           (16.58 mv)                

 

 

 

 

*      Partial period data

 

**     Connected to free floating end of3.2m long CSC panel strip (50mm wide)

 

         Finally, we have combined the analog sensor measurements (LM302 laser off) of

the three separated test periods in real time. From the combined file, we determine the

raw standard deviations (resolutions), the long term  drifts, comparisons to temperature

sensors, and  drift  corrected standard deviations. The resolutions are given in Table QQ below:

 

Table QQ -Long term Resolution: June-July-August-Sept Data – fit across 8.51M sec

All data; no corrections, no drift removal; other than DV shifts for LM302on data

 

Xtilt         sQx = 0.018835 arc deg (1.13 arc minutes)          12 V Ref   sLV = 2.61 mv

 

Ytilt         sFy =  0.040467 arc deg  (2.43 arc minutes)

 

Z4M-MAB(JulyAugSept)                                sZ4M-MAB       = 101.44  mm

    

LCP8-10 Z-Transfer Plate(JulyAugSept)        sLCP8-10 (ZTP)  = 15.27  mm

 

ME2/2-Transfer Plate  R                                  s ME2/2-TP R   = 40.27 mm

 

ME2/2 Inner – ME2/1 Outer  R                       s ME2/2-ME2/1 R  = 112.94 mm

 

       Looking at all the sensors, we can see them track/react to the average temperature

changes in the different test running periods. Unfortunately, we did not have a MAB in

June, so we only have comparable Z4M-MAB and LCP8-10 data for two periods, so

we don’t have tracking proof positive in these cases as for sensors in three periods.

Also the ME2/2-ME2/1 R connection was changed in September.Disregarding any

of the drifts as temperature correlated, sensor Drift Limits are established by

a linear fit of June-July-Aug-Sept Data plotted in real time across 8.51M sec and are

given in Table RR below:

 

Table RR -Long Term Drift Limits:

 

Xtilt        Qx = -0.21259 arc deg  – 1.1995e-08  arc deg/sec     (0.170 arc deg in 8.51 M sec)

 

Ytilt        Fy =   5.3311 arc deg    – 1.5176e-08 arc deg/sec      (0.129 arc deg in 8.51 M sec)

 

Where local T3 (shift) as a drift  is T3 = 289.78 – 9.2574e-08  deg K/sec

 

Z4M-MAB* =  47.387 mm          + 1.9962e-08   mm/sec            ( 93  mm  in 4.64 M sec)

 

ZLCP8-TP* =  8.6263 mm           – 3.527e-09     mm/sec           ( 16.4  mm  in 4.64 M sec)

 

ME2/2-TP R  =  11.036 mm         + 8.859e-09   mm/sec              ( 75.3 mm  in  8.51 M sec)

 

ME2/1-ME2/2 R = 38.954 mm+     -6.2823e-08  mm/sec **           (251 mm  in 4.1 M sec)

 

* July-Aug-Sept periods        

** There is thermal motion (wiggle/expansion) of the 3.2 m long free panel connected to the sensor

+ June-July-Aug periods

 

          All of the temperature sensors across the ISR test periods can be fit with a variation like

1e-07 deg K/sec and all of the analog sensors that are fixed to stable objects show a variation

like 1e-08 unit/sec.

          A simplest correction for thermal effects on the analog sensor readouts would be to take

the average of sensor  readings and temperatures  in each test period; choose one as a reference

and see if the variances are consistent with the  sense and magnitude of temperature differences.

We can try this procedure for three sensors that have data and invariant conditions in the three

test periods; Xtilt Qx, Ytilt Fy, ME2/2-TP R. Table SS gives the results below:

 

Table SS -Long Term Drift Limits with Simple Temperature Correction:

 

Xtilt        Qx = -0.23747 arc deg  – 9.1024e-10  arc deg/sec     (0.0077 arc deg in 8.51 M sec)

 

Ytilt        Fy = 5.3091 arc deg      – 5.2444e-09 arc deg/sec      (0.0446 arc deg in 8.51 M sec)

 

ME2/2-TP R  =  11.056 mm         -7.2693e-11  mm/sec              ( 0.62 mm  in  8.51 M sec)

 

With the resulting Long term resolutions

 

Xtilt                                              sQx = 0.0367 arc deg (2.202 arc minutes)

 

Ytilt                                               sFy =  0.0097 arc deg  (0.582 arc minutes)

 

ME2/2-Transfer Plate  R              s ME2/2-TP R   = 4.70 mm

 

 

        Even with the simple temperature correction, long term dirfts are dramatically reduced

and the effective long term resolution is improved significantly. In the future, we will calibrate

the temperature dependence of our sensors through detailed temperature cycling. Then we can

apply a real time correction according our T sensors which will improve the resolution and

stability even more.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10. Acknowledgements

 

 

                    We especially thank our collaborators of Northeastern University

         (J. Moromisato, Eb vonGoeler, R. Terry) who built the mechanical parts, calibrated

         and filtered the DCOPS sensors,  and worked with us in the development, setup,

         and some execution of the tests.

                   We also thank S. Hanson, E. Cowden, J. Lofgrin, R. Martin (Fermilab PPD

         Electronics group) and V. Sknar, E. Orischin (Petersburg Nuclear Physics Institute)

         for their development, construction, testing,DSP programming, etc. of the DCOPS

         sensor and electronics for the ISR I4 tests.

                   We thank the CERN Laboratory EP/CMS (A. Ball, D. Arevalo, R. Riberio)  

        for establishing  the ISR I4 test area, utilities, supports; for survey services and

        Photogrammetry (C.Lasseur, C. Humbertclaude, D. Mergelkuhl, R. Goudard,

        J.Noel. Joux and crew- CERN Geodesy). We also thank the Fermilab Geodesy

        (J. Greenwood and crew) for Photogrammetry measurements of our sensor assemblies;

        and the Fermilab Technical Division for CMM measurements of brackets and the transfer

        plate.