Bad connected accelerometers can lead to faulty behaviour of the vibration compensation system. This method can be used to check for problems with the accelerometers:
- Open the LAN Lab GUI in the corresponding lalas machine.
- Go to the "Vibration compensation" tab and inside that tab select the "Diagnostics" tab.
- Click "Enable diagnostics"
- In the "Dump file name" field enter the name for the output file, including the full path. For example,
/home/argos/VibrationAna/argos_dx_dump_20191014.dump and press <Enter>
- Take a data dump of a few seconds of vibration data by clicking "Start dumping".
- If a full path was given go to that directory or find the data in
~/apps/etc/<DUMP_FILENAME> if only a file name was given.
- Use the script
analysis_accelerometer_new.py from the attachments or copy it from
- Beeing in the directory of dumps and script one can get the plots below with ./analysis_accelerometer_new.py <DUMP_FILENAME>
Analysis of the results
The first plot gives an overview of all accelerometers, the signal computed for the compensation and the feedback from the mirror. In case of all accelerometers working it looks like Figure 1.
If one accelerometer is misbehaving, it can be seen immediately in the computed output of the compensation (Figure 2).
The second plot shows the Fourier Transform of the accelerometer data. There should be little low frequency content in the signal, as seen in Figure 3.
If there is a significant low frequency component, the guilty accelerometer is found, as Accelerometer 8 in the example (Figure 4).
- 21 Nov 2017