Servo tests 20071115
Servo tests 20071115
After the Nov2007 SMU overhaul a tilt of 6400, 5000 was needed to
zero out the observed pointing change. However, this resulted in
a very asymmetric and non-optimal servo performance, as can be
seen in the plots below.
The thick lines separate the individual throws, which have been
flipped alternatively such that the SMU in the plot always comes from
below. The red line indicates the chop phase and is at a distance of 1".
The DOT shows the 50ms timeout when the integration proceeds
regardless of the position of the chopper. The blue line shows the
difference between the demand and actual position of the chopper:
ideally it should be zero (the green line).
The conclusion would be that the pointing offsets needs to be taken
out as collimations while keeping the tilts at/near zero. The
resulting optical performance will need to be checked: if inferior the
possibility to shim the SMU should be investigated.
All tests were done with a chop-freq of 4 Hz. The chop throw, angle,
freq, and gain are shown at the top of each plot.
Chop: 180", Angle: 0deg (NS), Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Chop: 180", Angle: 90deg (EW), Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Chop: 180", Angle: 45deg, Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Chop: 60", Angle: 0deg (NS), Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Chop: 60", Angle: 90deg (EW), Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Chop: 60", Angle: 45deg, Freq: 4Hz
| SMU Tilts 6400, 5000 | SMU Tilts 0,0 |
|---|
| Plant gain 0.55 |
|---|
 |
 |
| Plant gain 0.75 |
|---|
 |
 |
Remo Tilanus
Last modified: Thu Nov 15 15:31:18 HST 2007
|
