Apr 102016
 

Ok, so remote means just a few meters away, either in the house or in the car. Somewhere warm anyway.

So, as mentioned in my previous post, I’d done a lot of research, and one of the things I came across was this video:

This is what I want to be able to do. I’ll never have the room for an actual observatory like this one, but I could at least automate a lot of the work. That’ll scratch at least two, maybe three, of my geek itches. Of course, everything has to be Linux based, and also as cheap as possible. With that, I decided on at least the following to start with:

  • AstroEQ – Definitely needed goto support on my EQ5 mount to start with.Fully made systems can be bought (minus steppers and mounting hardware), but I already had most of the parts laying around the place so decided to make it myself using an Arduino Mega
  • Indilib – This, running on a raspberry pi acts as a remote control server for anything that I wanted to add. All devices had to be supported, or easy enough for me to add with my limited programming skills.
  • Guide Scope – These are used to ‘lock’ onto a star and make sure that the telescope mount follows it precisely. Long exposures of up to even 30 minutes can then be achieved without too much difficulty. Initial plans are to try and use the Raspberry Pi camera (will try both standard and NoIR) versions.
  • Focuser – Last essential part for remote control is the ability to focus the telescope. This will use the DSLR attached and a stepper motor coupled to the focus knob. There are a couple of arduino based projects that emulate the MoonLite protocol, which is supported by indilib.

Once I’m happy with this lot (and I *will* blog my progress) and have some of my other projects finished (*cough* R2), then I want to take a look at a couple of other add ons such as:

  • Filter wheels – I can use kstars to take many photos with different filters in place, and also with a black filter I can automatically take dark frames for stacking images. (Dark frames are used to remove noise in the picture that is generated by the DSLR)
  • Auto lens cap – A simple servo driver to cover the telescope main lens. Not really necessary, but figured it would be a nice project.

I should be able to do all of this fairly easily. I already have most of the components necessary, and the software running on my workbench. One of the big issues I’ll need to work on is just how to mount it all to the scope and stop the cables getting tangled!

My next blog should be on building and configuring the AstroEQ.

Apr 052016
 

Hi, my name is Darren and I’m a serial hobbiest.

Well maybe not that bad, most of my hobbies are pretty much related (electronics, computers, science), and a lot are things I’ve been interested in since I was a kid. Most recently, I’ve invested in a fairly decent telescope and mount to do some visual astronomy, but more for astrophotography. I want to take pretty pictures of things very far away! So after a lot of reading of various blogs and websites (Star Gazers Lounge forum is fantastic), and watching numerous youtube videos, I got a tripod for my camera and a couple of cheap lenses off eBay. That is all that is needed and you can get some half decent shots.

My astrophotography album

But it wasn’t enough. So I dove back into the forums and did even more research, and learnt a few important things.

  • Telescope – Numerous different types, mainly split into reflectors, refractors, and catadioptric. All have their benefits and downsides, but for doing astrophotography the telescope isn’t the most important item surprisingly.
  • Mount – This, for astrophotography, is the most important thing to get right.You need to have a solid mount for doing anything more than a few seconds exposure, and one with tracking in Right Ascension at least, to track the stars. And it really needs to be an equatorial mount to avoid rotation of the starfield as it rotates.
  • Eyepieces – You need eye pieces to view through a telescope, and the shorter the focal length, the greater the magnification. These are generally only used for visual astronomy, as cameras bypass the need.
  • Camera – Most DSLR cameras block out a large part of the infra red by design, but you can get them modified to remove this filter and get much more vibrant images. Its not a necessity, but definitely a nice to have.

Whilst learning all this, I had a thought in my head about some form of computer control (Linux based, of course) and actually stumbled upon a few projects to help with this. The first was AstroEQ which was an opensource ‘Goto’ system (select a star, and the telescope will automatically move to center on it) designed around an arduino. That was a perfect start for me, and I was pretty sure I could get it working from Linux. Thats when I discovered indilib!

Indilib is an open source system for controlling all sorts of astronomical instrumentation, not just goto mounts, but also things like auto focusers, digital camera, filter wheels, and other custom devices you may want. Even better, all this can be run from a Raspberry Pi as the control server and a laptop using the actual astronomy software. This would mean I could set it all up, and retreat to somewhere a little warmer to actually do my observations and photography. I’m sure this is against the amateur astronomers code or something, but damn it gets cold out there.

Along with indilib, there is kstars. This is a planetarium program written for the K Desktop Environment, and with EKOS plugin can control any indilib hardware. Not only that, it can schedule work and sequences, and help you plan your observations.

I’m going to (try to) write more blog posts chronicling my progress on getting all this set up, and some HowTo posts on using indilib on a raspberry pi, with kstars, and any custom hardware I make.

Mar 262016
 

It seems that xmas and new year is when all the part runs start. At least that is what it feels like to me, for all the parts I want.There has been a sudden rush in ordering things for R2 which means I nearly have everything I need to get him put together and mobile. The one part I’m still missing is the outer ankles, which I am hoping will be on a run soon. The last few cosmetic pieces I need are due soon too, such as utility arms and LDP. Progress whilst waiting for these parts has not been too bad, but I do keep coming across problems to work around. I guess that is the fun part tho.

On the electronics front, I managed to (I think) blow up my amplifier. I still need to hook it all up again and test it. I’ve a feeling that the switch I’ve got for main power isn’t rated high enough for the current that is going through. I’ve also decided to change the layout of everything, and install an actual touch screen inside R2 for the Raspberry Pi. This will give me the ability to control certain aspects of the software, and also at a pinch I can plug a usb keyboard and mouse in to do onsite programming whilst away at a convention or such like. I’m also currently waiting a Raspberry Pi v3 which will give R2’s brain a bit of a boost. Overall design hasn’t changed much, it’ll still all be controlled via i2c, but will also have wifi and 3g internet connectivity, turning R2 into a wireless hotspot! I will have to see how much the aluminium body affects the signal, but can always put an external antenna somewhere.

IMG_0298_CR2_embeddedI have more or less got the legs finished, and have done a test fit! Must say, they are looking rather good. All the parts slot nicely together and are pretty solid. Of course, I still have the problem of a lot of the screws and bolts being imperial (We’re part of the rebel alliance, don’t want any of that imperial rubbish!) rather than metric, so getting hold of replacements can be tough. This is more of a problem seeing as I’ve had some of these parts for quite a while and not only been moved around the office in the old house, but have moved to the new house and gone in and out of the garage, so some of the fastenings have been misplaced along the way.

I also decided to get one of the nice new hydro formed domes that are available. I was never too keen on the existing one that I had, and the new domes come with the mounting ring to fasten it to the body which meant one less thing I had to fabricate. A lot of the tutorials on the forums are geared around these domes too. Not only did I get a new dome, but I figured whilst I was doing that, I’d also upgrade all the things to go in the dome. This meant getting the ultimate hinges, aluminium holoprojectors, aluminium logic surrounds, aluminium eye, and even the fancy PSI holders. All this together gives me a pretty much top of the range dome for R2. It also means I can do a quick and dirty rebuild of the old dome at some point and create a different astromech.

IMG_0304_CR2_embedded IMG_0309_CR2_embedded IMG_0489_CR2_embedded
Which brings me more or less up to date. The dome is nearly finished, I just need to put a few final touches to it and tidy up the cabling inside. I even got the dome servos all hooked up and took a short video. I need to replace the arms on the servos with something a bit longer to get a bit more throw on them, but overall I’m pretty pleased.

Next step is to get to work on the body. I’ve got some of the ultimate hinges and have some installed already. Just need to fit the servos to them. I also need to trim down my data panel to fit it into the breadpan, but that shouldn’t be too much trouble. The one part I’m having issues with is the charge bay breadpan, it just doesn’t want to fit in properly. I may have to resort to some pretty hefty modifications on it.

 

 

I’ve given myself a deadline of June to get him mobile, but that depends on when part runs happen. Fingers crossed the outer ankle run starts soon.

Dec 042015
 

11934535_10156061505195316_3190924556943319116_oIts been a long time since an update, but we moved house at the start of the year and things have been hectic. At least, thats my excuse and I’m sticking to it! I have been making progress with R2 in the last couple of months, doing a lot of work on his brain for starters, and painting various parts.

Code wise, there has been a couple of fairly drastic rewrites since my last update. The interface is a REST API, which sends commands to various modules as before. I’ve added a scripting module now, so that scripts or loops can be initiated such as random sounds, or a dance routine. The servo module had to have a major rewrite too as I discovered that I could only control one servo at once and had to wait for that to finish before another command could be sent. That wasn’t much good! I’ve also written the first of the actual controller interfaces (not counting a simple web one for testing), R2 can now be controlled from a PS3 controller. Button combos are read in from a csv file to trigger certain effects or scripts. Lastly, R2 now has a voice, and can play any mp3 stored in a directory, including selecting random ones from a list of types. Next step is to get either the Pi or the A la mode Arduino to control the speed controllers. I don’t want to run them off the Adafruit i2c servo controller for safety, I’d rather drive them directly and have some form of watchdog to make sure R2 doesn’t go on a rampage. All the code is still available on GitHub under my user, dpoulson

The PDU also needed a rethink, not least of all because of the amount of current it needed. The setup now has feeds directly to the speed controllers, with relays on the output from them to the motors so I can break the circuit if needs be. These relays will automatically turn off if the battery is disconnected so that any pushing of R2 will not feedback into the speed controllers and fry them. The relays will also be controlled from GPIO pins on the Raspberry Pi so I can disconnect them via an API call. I’ll also have an input for a kill switch that will have to be permanently on if any of the motors are to be powered, possibly using a transmitter in a replica droid caller or hilt of a light saber. I’ve a base idea for the new relay controls:

Powerswitch The relays I’ve found are Omron G4A-1EA, which have the benefit of the switched load being on spade connectors on the top, rather than through PCB traces, which when I did the calculations would need to be massive to support the potential current running through them. This allows me to make a simple PCB with the controller circuit, and hook the 24V battery up to it to power the coils. If the battery is removed, the coils turn off and the circuits are broken. No fried speed controllers.

The 24V connection will probably go through the fuse box I’ve installed, with a hefty fuse. The makers of the speed controllers don’t actually recommend a fuse but I’ve seen a few comments saying a 60+A fuse can’t be a bad idea, just in case!

The battery will connect directly to the center contacts of a DPDT switch, with the fuse box on one side, and the charger connection on the other. This will allow charging the batteries without taking them out of the droid. Not sure if this is best practice or not, needs more research. Currently they are just a pair of 12V SLA batteries that I had, connected in series to give the full 24V.

I’m hoping to get some time either this weekend or next, to hook up the motors, speed controllers, and battery, to test them out and get an idea of potential current draw. They’ll be controlled with a standard RC transmitter/receiver for now. If I can get the legs onto R2 he may even be drivable by xmas.

Fingers crossed!

Mar 302014
 
Finally got round to cutting some holes into R2's dome. He now has lights! :)

So, finally got some time on a weekend with nice weather to get outside with the inner dome and my Dremel. Whilst the dome set I got had a laser cut outer dome, the inner one was totally uncut. The aluminium domes come as an inner and outer to allow you to have the indent around each of the panels, and also lets you have a nice lip if you have the panels opening, which is something I want. Of course, this means lots of holes to cut. Any panels that are going to open have to be cut out, as well as all the holes for the lights and holo projectors (HP).

IMG_0182To start off with, all the holes were marked using the laser cut outer dome as a template. HP and light holes were to be the same size as the outer ones, but the opening panels need more of a lip. A tip I learnt from reading other builder’s logs was to use a large washer, and to put the marker pen in the center, then roll it around the edge of the opening. This gives you pretty much a perfect size for the lip. Next comes the scary part.

Cutting disc grave yard. They really don't last long, and some of the shattered. The larger ones broke in the center so were unusable.Cutting the dome! These things aren’t exactly cheap, and even worse they’re quite hard to come by, having to wait for runs to be done of them by the guys in the states. But, its got to be done so I got the Dremel and a whole bunch of fibreglass reinforced cutting discs for it. I needed a lot as the wear down extremely quickly. I went through over two dozen of them just on the dome. Thankfully I got plenty.

I found the easiest way to do it neatly was to do the large part of the cutting with the dremel, at least enough to make a cut a few cm long so that I could get the hacksaw into the hole. The hacksaw made a much cleaner cut with more control. The Dremel had a habit of biting in and running off a bit, which made some of the fine cuts a bit difficult. By far the hardest bits to do were the circles for which I ended up making a load of straight cuts through the center to form a star pattern, then gradually cut each of the prongs off. Once I had the main parts cut I attached all the cuts with a large file to take it to the lines I had drawn.

All the pie panels done now, along with the top HP. The metal on the spun domes is a fair bit thicker at the top. Just needs a load of filing and sanding to make smooth and safe.It took a good few hours to get through everything, but it was worth it. The holes are still a little rough and still need some sanding down with wet and dry. Also the circular holes all need to be made a little bigger. They were originally marked up to be the same size as the outer dome holes, but ideally they need to be at least a few mm bigger, especially the HPs. Another tip that I’ve found on the net is using a glass wine bottle to help with the sanding of the circular holes. Wrapping some wet and dry around the neck, you can sand in a circular motion to get an even hole.

Still left to do are the rear PSI holes, in both the inner and outer domes. It is the one outer hole that wasn’t pre-cut, so I need to be extra careful with the outer part. The current run of laser cut domes are a lot nicer, with the inner and outer ones laser cut and all just about ready to just polish and paint. Also, I think I’ve been fairly lucky with this dome, as a lot of people report having to cut the inner dome in half to get the inner and outer to fit together properly.

Finally got round to cutting some holes into R2's dome. He now has lights! :)Once the last PSI holes are cut I’ll be ready to bind the two domes together permanently, which is another scary one way step. I’m making sure I’ve as much done with them separate as possible to avoid damaging the outer dome with a slip of the Dremel. I still couldn’t resist having a test fit of the two domes and inserting some of the lighting. It looks pretty good.

Next main steps once its all bonded is to install the main radar eye which I’m hoping to bolt on to make it removable, and then I have to source a load of hinges which seem to be either very expensive, or hard to find.

All in all, a good weekend of work. I would’ve like to do more but due to losing an hour due to the clocks changing, an early morning call from work, and Mother’s Day, I didn’t have much time on the Sunday to do much. Fingers crossed for nice weather again next week to finish off the Dremel work outside. I might also make a start on the skins too.