Fix Version/s: None
Sprint:TSSW Sprint - May 09 - May 23
Team:Telescope and Site
Support the rotator test on summit. This is to support the test case by Ander to debug the rotator's movement.
The github issue is: negativeMoveOscillations. The branch of Simulink model is issue37.
There is one test case:
1. Increase the preloading of the system (3% to 20 %). We will do this slowly to collect the data. Need to check the MOOG's implementation for this.
PS. The story point here contains the effort in
We did the tests on summit as the attached file. Doug preferred we analyzed the data first to check the preloading value based on the currents before doing the test of different preloading data.
Organized the comparison: Rotator Data.pptx.
Thanks Te-Wei! Data taken and directly analyzed. Very efficient!
There will be a part 4...
The first observation is that the original Moog software appears to be using a preload of 0.6/4 = 15%. The 0.6 is approximate average of the ± currents on the graph on page 2 left side.
Per Austin's comment Moog had the current limit set at 3.6A. However, it appears from the Tekniker manual page 22 figure 33 that they raised this limit to 4.0A. If my understanding is correct the current limit should be reduced back to the specified 3.6A. The current limit was set to meet the requirements of limiting the torque to prevent damage to the cables and Hoses. We should probably be using the same preload.
The plots on page 3 show negligible preload. It appears that the values are ~+/-0.05 amps or about 1%. It appears in the Tekniker manual on page 23 figure 34 that the preload was set to Tq = 0/100. Does this mean no preload or? These plots show oscillations between positive and negative torque. Whenever this happens instability is expected produced by the small gap between the gears.
There is a reasonable chance that increasing the preload, tq, will resolve this issue. The other possibility is that we should reduce the gains. The rapid oscillations imply high gains which are unnecessary. Figure 34 appears to show a gain, Kp of 10/100 (10%?). This is a fairly small gain but we may try reducing it. We do not need a fast system. We need an accurate and stable one.
Prepared the test case.