Flip Flat behavior question

Sequence Generator
#1

I recently had a flip flat installed on my scope at a remote facility. It’s a large 13" panel that uses the Alnitak protocol. While the scope is parked (at a custom position), the flip flat can open without any concern that the flip flat will contact the roof. However while the scope is “upright” (for example at the CWD position), if the flip flat were to open while the roof was closed the flip flat would contact the roof. I’m not concerned about that at the start of a sequence because the roof will be open.

My question is, what is the order of events when something triggers SGP to end the sequence and run end of sequence options? Will the scope park and then the flip flat will close, or does the flip flat close first?

I can see a scenario where the remote facility’s safety monitor closes the roof in the middle of a sequence. At that point SGP will shut things down and I can see a specific set of circumstances that will cause the flip flat to contact the roof if not handled properly.

#2

Currently parking occurs prior to closing the flipflat shutter. That said, it seems like a good idea to reduce the profile of the scope before moving it inside tight quarters. It’s easy to change, but I always wonder if the current order is purposeful for some other reason I can’t conjure right now. Thinking…

#3

Parking the scope first and then closing the flip flat is great for my scenario. As long as it happens in that order I’m good.

#4

Ken, last night I watched SGP during an abort due to a lost guide star. I decided to end the sequence and run end of sequence actions. Upon doing so the flip flat closed right away while the mount started parking. So that behavior is opposite from stated earlier. Is it possible to make sure the mount parks first before closing the flip flat?
Let me know if you want the log.

#5

Well, it is the order in the code, but we can’t guarantee that the mount will perform a synchronous park. In other words, the mount is asked to park and then SGPro is unable to determine the duration of the movement and then, immediately after the flipflat shutter is closed. We make an effort to only perform a single mechanical movement at a time, but we can’t force the driver to do this. I suspect that what is happening is that the mount receives a command to park, then SGPro is unable to determine the status of the park and then continues on with the next step (which is with the flipflat). We can take a look at the logs to confirm tho…

#6

Here’s the log.

sg_logfile_20220729204138.log (266.3 KB)

#7

Oh, actually, I know what’s happening. I completely forgot, but last year, we did actually make mount park an asynchronous action. The reason we did this is because:

  • some mounts did not reliably report park as completing and downstream shutdown actions would not occur.
  • sometimes shutting down with haste is important and this action can possibly occupy a lot of time.

I thinks it possible to add (another) option that enforces serial execution of movement, but I’d need to think about it for a minute

#8

As it is now there is a very high likelihood that if the observatory roof closes because of unsafe conditions my flip flat will contact the roof unless it is parked first. The roof won’t notice it at all but my flip flat will :slight_smile:
I realize this is not a common case…

#9

On the other hand - if the Flip Flat does not close first, you will have the mount slewing around with the flap open - and more likely to come in contact with something in some setups. I don’t think it affects me either way - but if it is going to be changed…then there should be an option for whatever action happens first. It may be important to some!

#10

Agreed that it needs to be an option if anything does change with this.
My flip flat goes all the way back to the OTA so it is “flat” against the OTA. That was a necessity because it’s 13" in diameter for a 12.5" scope. Otherwise it will be a wind sail and maybe still will be…the jury is still out on that.

#11

I probably have one of the earlier ones??? Mine does stick up proud of the scope. I am not worried about the wind because it is within a dome…but I do wonder sometimes if it is catching and reflecting moonlight. :thinking:

1 Like
#12

I probably should have mentioned that my flip flat is a DIY one that I designed and made using a 3D printer. It uses the Alnitak protocol. Because I had to make it as light as possible the frame isn’t particularly strong and in all honesty I expect the first gust of wind over 15mph to break it. It uses a 270deg 35kg servo motor so that it can fold back against the scope.