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Mount park detection system - how?

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Hi!

I'm trying to automate the observatory and I think the roof is working ok now and it seems to work also with ekos weather system. Here I am using an all-sky camera to just count starts and report bad weather if I see too few stars. All seems ok. I'm using a RPI 3 for ekos and kstars, but hopefully I can move to RPI 4 when Ubuntu starts stabilizing.

Now, my problem is that I can only physically close the roof if the mount is truly in it's parked position, otherwise the roof will hit the scope. The parked position is with the telescope to the west and pointing slightly downwards. The mount is an old eq6 fitted with synscan upgrade and controlled using eqmod.

My fear is, that something goes wrong with the mount and it is not truly parked, e.g. because it have bumped into the pier instead.

Any good ideas on how to design a reliable sensor system that will tell me if the mount succeeded in parking or not? I'm not a sensor wizard, so no idea what to look for. Programming it will be no problem....

Best regards
Søren
4 years 3 months ago #46854

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Would it be possible to have a microswitch that will be operated by the OTA as it reaches the park position? You can get microswitches with long arms that are designed for this sort of thing, you may already have some on your roof.

The switch is connected to an input of your observatory safety system, the rest is just software.

Chris
4 years 3 months ago #46864

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Another suggestion I've seen is a infrared transmitter and receiver or reflector, where the receiver is effective when the scope is in the parked position.
I wonder also about using an accelerometer something like learn.adafruit.com/adafruit-lis3dh-tripl...ter-breakout/arduino
4 years 3 months ago #46877

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As Wotalota was suggesting, what you should look for is an electronic eye to sense when the mount it in a safe position.
Here is an example I've seen previously, although I'm not sure if the link will work because it is a Facebook group post.

www.facebook.com/1327031179/posts/102165...9/?sfnsn=mo&d=n&vh=i

It shows a mount being command to park in a safe position on command with an IR transceiver pointed to a retro reflector on the scope. Such a rig could probably be put together with an Arduino and garage door hardware.
4 years 3 months ago #46894

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Thanks a lot, I will look into the IR reflector things. It seems they way to go.

The movie worked fine and looked awesome :-)

I use reed switches for my roof, btw. They seem to function nicely for the roof, but I can not imagine how to connect them to sense if the scope is parked or not...
4 years 3 months ago #46903

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I did find a long time ago a website selling parts for mounts, cannot find it again, but I did manage to find the model of the sensor:
uk.farnell.com/eaton-cutler-hammer/1451e...ic-sensor/dp/1771219
I thought about including it in my electrical circuit for the roof. Just an idea for you ^
4 years 1 month ago #49699

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Hello Søren

having my mount and telescope seen more than once in this position:


I was looking for an solution too. I used two acceleration sensors, a bit of math and the assumption, that the hour axis is aligned (including C++ source) to get the absolute orientation in space. The accuracy is about +/- 0.2 degrees.

Lately I stumbled over a more recent product: Adafruit 9-DOF Absolute Orientation IMU Fusion Breakout - BNO055 .

Kind regards, wildi
4 years 1 month ago #49983

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I use this kind of limit switch to check if my roof is closed or opened.


In fact, I do have a couple of spare ones, I think I'll add one to be sure the scope is 100% parked.
If you do go down that route, do not get a micro switche, I used them before and they do fail as they are fragile. Get that heavy duty like in the picture above there.
Last edit: 4 years 1 month ago by Gonzothegreat.
4 years 1 month ago #49984
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