Auto roof closing - how to determine if scope is in the way?

[blinky]

As the title says, if you have a roof with a way to remotely close it (I'm thinking of a sliding roof, rather than a dome BTW), how/what do you use to ensure the 'scope is not still unparked and in the way? I know there will be a way to determine if the scope is parked but I want a sort of fail proof method, with some sort of beam sensor? Only this with that, is what if the scope is at an angle to the horizontal and misses the beam but is still high and so hits the roof? Does that make sense?

[pete_l]

Lasers.

Small. cheap ( < £5 a pop) and can be run from a digital I-O port of an Arduino, Raspberry Pi or other SBC.

I'd have one attached to the roof/beam that could potentially hit the scope and a light-sensitive resistor (also connected to the SBC) at the other end of the beam. Have the laser come on as part of the parking / roof closing process and don't start the closing motors if the light sensitve resistor isn't seeing the laser's light due to an obstruction.

Failing that, as ultrasonic rangefinder setup connected to the roof as it closes. Use that to stop the closing if the rangefinder detects an obstruction that's too close.

[Nillchill]

If it goes 'CRUNCH' it was in the way!

[paulastro]

I'm afraid I'm not very technically minded. I have a very low profile sliding aluminium roof observatory. I'll know when I've got it wrong when my refracor is bent through ninety degrees and I can't see starlight through it!

[Zakalwe]

What about a micro-switch on the mount that senses when the RA axis is in the right spot?

[blinky]

I thought about a laser beam system but my roof is not flat so potentially the scope could be at an angle and miss the beam but hit the top part of the roof. The micro switch idea might work though, I just want a way to mechanically check if the mount is parked...

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[JamesF]

A sprung "bumper" on the leading edge of the roof that kills the power if it hits something?

Or just make the walls higher

James

[JamesF]

Actually, how about a couple of optical sensors attached to the mount so they only line up when both the RA and DEC axes are in the "home" position. Unless they're both on then the power to the motor is cut (and you get a nice little idiot light showing somewhere, so you know why

James

[Nillchill]

On a serious note:

If the roof is auto closing, i assume you have some logic to determine the need to close the roof, so why not signal the scope to autopark in a safe position first, then close the roof.

Cheers

[mallorcasaint]

Why not put in an infrared wireless IP camera. £35 from Amazon and you can monitor it from anywhere including on your phone. We use one as a "Granny Cam" to monitor the mother-in-law!

[dmahon]

There are a few bespoke bits around, but they're not that cheap:

http://fostersystems.com/viewitem.php?productid=85

http://www.backyardobservatories.com/automation.htm

[ncjunk]

I'll be sticking some reed switches on the ra and dec. These will be chained in to the power for the roof motor and only if on, the safe position, will the roof have power and be able to close.

I'm thinking of adding bumpers on the roof with sensors as a fail safe. These will either be linked into the roof motor controller safeties or daisy chained into the motor power to disconnect it, NC Switch state.

Lasers with an ldr would be fiddly, i was thinking of the light beams on the sliding gates but i'll put those in for human protection and not scope protection.

I have the 35pound ip wifi motorised camera and its a must have. Its cheap and you can check on the scope from anywhere in the world using a mobil, and control it. Well i've only tried from spain and england so far.

I also have an arduino controlling 8 relays which switch ppower via a webpage, thats also damn usefull.

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[ncjunk]

I was also thinking of using opencv, open source computer vision, libraries to us the ip camera picture and detect the position of the scope. Basically i could put different coloured strips on the scope and use them to detect orientation. (Should be easier than it sounds but its a bit bespoke)

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[yesyes]

Depending on how exactly you would determine when to close the roof, you could query via ASCOM whether the mount is parked before closing the roof.

I'm planning to do something very similar. I haven't yet looked into it in detail as I have to finish building my obsy first.

[yesyes]

http://fostersystems...hp?productid=85

This one is quite clever, actually. Instead of having the beam across the leading edge of the roof, there is a reflector on the scope that only reflects the light beam back to the sensor when the scope is in parking position. This could probably be replicated with a laser, mirror and LDR in the right places.

[blinky]

Interesting ideas - I don't want to use Ascom Park etc as I want this to be failsafe..... Reflector on the scope and the reed switches are good ideas though!

[nickdud]

take a look at safety edge beams as used by us lift engineer types.

http://www.shorts-lifts.co.uk/lift-components/lift-safety-edges/strack-lift-automation-lift-safety-edges/

http://www.memco-global.com/products/light-curtains/

http://www.motion29.com/products/se/default.htm

or just mount a "parked" switch on your scope mount somewhere maybe?