You are here: Foswiki>Engineering Web>Vibration>OVMSSystem (18 Aug 2010, JorgeEsguerra)Edit Attach

UEI RackTangle Output Verification

OVMS Quiet/Short Testing

OVMS General Information

Requirements

Test Reports

Installation

Proposed locations of OVMS accelerometers (as of 2 December, 2009)

Location Quantity Comment Status
SX M1 5 3 OPD, 2 lateral Not installed
DX M1 5 3 OPD, 2 lateral Not installed
SX M2 5 3 OPD, 2 lateral Installed
DX M2 5 3 OPD, 2 lateral Installed
SX M3 5 3 normal to mirror, 1 parallel to plane of mirror, 1 parallel to ground plane (at zenith) Installed
DX M3 5 3 normal to mirror, 1 parallel to plane of mirror, 1 parallel to ground plane (at zenith) Installed
L-N Rails 6 total for L-N not installed
LBTI Rails 6 total for LBTI not installed
"floaters" 3   not installed
Total 45    

-- JorgeEsguerra - 18 Aug 2010

M3 Accelerometer installation locations (pictures)

-- JorgeEsguerra - 18 Aug 2010

Pre-OVMS Commissioning Data Sets

-- JorgeEsguerra - 10 May 2010

  • NOTE: Data collected with the OVMS RackTangle between September 2009 and January 2010 is affected by timing issues. The scan rate discrepancy impacts analysis results slightly. See here: UEI RackTangle + AI-211 Scan Rate Discrepancy

-- JorgeEsguerra - 03 Feb 2010

-- JorgeEsguerra - 30 Nov 2009

OVMS Hardware

Computing / DAQ

A/D Gain selection

* Obtain the gain you want by fiddling with the max/min expected measured values

* Creating an accelerometer seesion automaticall sets the gain based on expected measurement magnitude

* You can "set" the gain by specifying expected measurement values using this Voltage / accleration / gain table

-- JorgeEsguerra - 04 Feb 2010

OVMS Accelerometer Data

-- JorgeEsguerra - 02 Feb 2010

UEI RackTangle + AI-211 Scan Rate Discrepancy

  • Discovered January, 2010. Affects LBT data collected between Sept 2010 and January 2010.

  • Analysis of data collected with the OVMS UEI RackTangle indicates that there are discrepencies between the user-specified scan rate and the actual scan rate. UEI has reponded that this is normal behavior.

  • The discrepancy was observed when using clock triggering off of the 24-MHz and 66-MHz clocks. Based on user specified scan-rate, the software/firmware selects a scan-rate that is close to the user specified rate.

  • The user is then responsible for verifying the actual scan-rate that data is collected at by reading the scan-rate output or calling the appropriate libraty functions to write/display the scan rate.

  • An on-board PLL can be configured (software) to provide triggering as well. However, it was observed that the scan-rate displayed using the LabView library is incorrect, displaying user specified desired scan-rate and not the actual scan rate.

  • Below is a list of scan-rates for LabView operation of the UEI RackTangle with AI-211 devices installed, and triggering from the on-board 24 and 66-MHz clocks:

User specified scan rate (Hz) Scan rate reported by LabView (Hz) Scan rate confirmed through (FFT) analysis
64 64.45 no
128 128.906 no
200 201.416 no
256 257.812 no
300 300.481 no
400 402.832 no
500 503.54 no
512 515.625 no
600 600.962 no
700 700.577 no
800 805.664 no
900 901.442 no
1000 1007.08 yes
1024 1031.25 no
2000 2014.16 no
2048 2062.5 no
2500 2503.03 no
3000 3024.19 no
3500 3531.68 no
4000 4028.32 no
4096 4125 no
4500 4523.03 no
5000 5006.07 no

-- JorgeEsguerra - 02 Feb 2010

  • Below is a list of scan-rates for LabView operation of the UEI RackTangle with AI-211 devices installed, and triggering from the on-board PLL:

User specified scan rate (Hz) Scan rate reported by LabView (Hz) Scan rate confirmed through (FFT) analysis
1000 1000 (wrong) 982-Hz (estimated)
1018 1017.99 (wrong) 1000-Hz (estimated)

1000-Hz UEI data acquisition scan rate correction:

1000_Hz_Fs_correction.jpg

  • 1000-Hz UEI data acquisition scan rate correction. (Uncluttered):
    200_Hz_Fs_correction_naked.jpg

  • Example of scan rate error: Analysis of 300-Hz sine:
    300-Hz_sine_showing_Fs_discrepancy.jpg

  • Example of scan rate error: Analysis of 300-Hz sine (zoomed):
    300-Hz_sine_showing_Fs_discrepancy_zoom.jpg

200-Hz UEI data acquisition scan rate correction. (Uncluttered):

200_Hz_Fs_correction_naked.jpg

-- JorgeEsguerra - 10 Feb 2010

I Attachment Action Size Date Who Comment
300-Hz_sine_showing_Fs_discrepancy.jpgjpg 300-Hz_sine_showing_Fs_discrepancy.jpg manage 129 K 03 Feb 2010 - 19:00 UnknownUser PSD of 300-Hz sine wave illustrating scan-rate issue.
300-Hz_sine_showing_Fs_discrepancy_zoom.jpgjpg 300-Hz_sine_showing_Fs_discrepancy_zoom.jpg manage 148 K 03 Feb 2010 - 19:01 UnknownUser PSD of 300-Hz sine wave illustrating scan-rate issue. (Zoomed.)
ScanRates.xlsxls ScanRates.xls manage 21 K 03 Feb 2010 - 19:17 UnknownUser Scan-rate list in MS Excel format
Topic revision: r18 - 18 Aug 2010, JorgeEsguerra
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback