Dome Pie Panel Control

I’ve almost finished the electronics and programming to control the new hinged pie panels. I’m using a small 18X PICAXE micro-controller coupled with a few buttons on the RF remote.

Check out the video of the panels in action.

I’m also in the process of replacing the veclro that attaches the servos to the dome with something a bit more permanent. The brackets are made from aluminum angle (1.5″x1.5″ and 1/16″ thick).

http://www.artoo-detoo.net/gallery/v/build/dome/IMG_1319.JPG.html?g2_imageViewsIndex=3

They’re attached to the top of the hinge and the bolts from the mounting plate that already fix to the dome.

As a side note, if I was doing this again I’d adjust the hinge position a tad. The pies open to the vertical position, but it would have been nice if they’d open a little further, and I figured out (too late) that the lower the hinge is on the pie panel the further it will open – but too far and the hinge will not clear the dome properly.

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Posted by Chris on July 17th, 2008 in Dome, Electronics | 2 Comments

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Life Form Scanner Screen Material

I’ve finished re-installing the pie panels using hinges and servos, so now I’m starting to think again about the gadgets that pop out, like the Life Form Scanner as seen in ESB.

Yesterday at Ace, I found some perforated brass sheet that’s close to the screen material used in the movie. It was $25 and probably big enough to make at least 6 screens. According to the label the product is distributed by K&S Engineering, Stock No. 6412, UPC 6 76116 06412 2.

I’ll have to paint it silver, and the perforated design is not totally accurate but it’s close enough for me.

I’ve also been researching mini/compact power antennas for the Life Form Scanner lift mechanism.

Posted by Chris on July 12th, 2008 in Dome, Electronics | 3 Comments

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Dome Pie Panel Servo Setup

Spent the last few evenings working on the dome pie panels, and after some tweaking I think I have a setup I’m happy with.

I ended up keeping the extra plate on the inside of the pie panel. It adds some detail and I like the sound the panels makes because of the extra weight. I left the hinges in the default configuration with no tweaks apart from drilling some holes to attach the servos.

I glued the hinges in place using CA glue, which sounds like it may not work so well, but I used the same glue on the hinges on the body and they’ve held up well.

Notice how the hinges are angled slightly to follow the curve of the dome.

I could have just glue the hinges directly to the dome, but I wanted to make the panels removable, so I created a small plate that glues to the dome and then then the hinges are screwed to it.

For the front Holo projector I’d purchased some push rod assemblies to attach the servos, but they were pretty expensive for something so simple, and I thought I could do better – this is what I ended up with.

It’s made up of some very cheap and readily available parts you’ll find at any hardware store. It basically some #4-40 and #6-32 screws in varying lengths, and short length of aluminum tubing that I cut up to make some linkages. I think it cost me less than $4 to make four push rod assemblies.

The long push rod is a #6-32 screw which attaches to the hinges via a piece of the aluminum tube that’s tapped at one end for the screw.

A long #4-40 screw passes through it horizontally to fix it to the hinges.

On the servo end I tap a small section of the tube on each side, and drilled a hole in the middle that allows the long screw to freely pass thru until I lock it on the side.

The servo is currently attached to the dome with some heavy-duty Velcro, which works fine right now, but I know it will eventually fail so I’ll be making a mounting brackets next.

Here’s a short video showing the setup in action

The next step is to wire all 4 servos into a PICAXE processor and tie it all together with some software to trigger sequences from the RF remote.

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Posted by Chris on July 10th, 2008 in Dome, Electronics | 1 Comment

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Dome Pie Panel Hinge Experiments

Adding hinges to anything on Artoo is tricky, with so many curves and often located in tight spaces it’s really hard to get things just right. I’d bought a bunch of the Robart “350” bomber door hinges a long time ago, and successfully added some to the power charging panel. They’re not cheap, but if you shop around you can find them for around $7 a pair.

There are other options that are cheaper, like the McMaster Carr steal hinges or the plastic one’s Calvin found for 30c. But the consensus seems to be that the Robart hinges are the way to go.

Some builders have had to reverse and trim part of the hinge to get them to work, but I’m not convinced it’s necessary for the dome pie panels. Here’s Keith’s explanation on how he uses them.

Most people seem to use epoxy to secure the hinges, but I also like how Calvin uses nuts and bolts for easy removal.

For my experiments I temporarily used adhesive foam tape, and played with several configurations.

I started off with Keith’s method of trimming and doubling up the hinges. I also added back the cut out from the inner dome to the pie panel to give it more weight and substance.

I found that by reversing and trimming the hinge, it has to sit right on the edge of the dome cut out – making it really easy to align – this is probably the only advantage I can see for flipping the mounting.

But I’m not crazy about how it look so close to the edge.

I also had to slightly file the inside bottom edge of the pie panel to get it to open cleanly.

For my next test I went the minimalistic route, and used a single hinge, configured the ‘correct’ way with it extending further into the dome. I also did not attach the extra cut out to the pie panel.

It was a snap to align and worked surprisingly well and opened just as easy as the first, if not easier. I suspect a servo would like the setup a bit better, being lighter and only having to move one joint. However, it felt more flimsy (obviously) and it would be super important to keep the single screw tight – which is hard to do on anything Artoo.

In summary – I like the heavy feel of the first option and how it sounds when it closes, but I also like the simplicity and cost saving of the second. I’m going to sleep on it tonite and get a second opinion tomorrow before permanently affixing anything to the dome.

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Posted by Chris on July 8th, 2008 in Dome | 2 Comments

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Dome Electronics Rewire

If you’ve been following along with the blog you’ll know that the electronics inside the dome have evolved a bit over the last 12 months. I’ve added more stuff, moved to a slip ring system rather than separate batteries, and in general created a wiring setup in the dome that’s not perfect and hard to maintain.

Over the weekend I spent a couple of hours trying to simplify and reworking the dome electronics and thought I’d post something on the path I took to get where I am right now.

I’d originally had the various components like batteries, RF Receiver, RC Receiver, Power Board all laid out on the dome base plate – and routed power up into the actual dome with a detachable “umbilical” cord containing the 9V, 12V and 24V. Inside the dome was a terminal block that the various LED boards attached to.

To regain the space for adding the periscope, fire-extinguisher and other gadgets I then moved to stacking the electronic boards in a carrier – also located on the dome base plate.

But over the last few months I’ve been having problems with loose wires In the dome. I’m using the European style terminals blocks and no matter what I do the wires eventually work loose. Not enough to cause the lights to fail totally, but enough be annoying and make them blink or reset when driving around.

I was going to replace the blocks with the more traditional screw down versions (as shown on the right below) and add crimp terminals to all my wires, but there’s still many points of failure so I decided to try and eliminate the “umbilical” cord all together.

With everything in pieces on my work bench it became obvious I could just move the stacked board assemble up into the dome and just use the slip ring wire to connect directly into the dome.

I added a small acrylic mounting plate to the side of the domes existing mounting system.

Then the stacked board assembly just slips in and holds snug, with some velcro to make sure it doesn’t move, but still allow for easy removal and servicing.

It’s a much cleaner solution, but I’m sure it’ll evolve again as I add more stuff to the dome

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Posted by Chris on June 10th, 2008 in Dome, Electronics | No Comments


Holo Projector Servo Test

I’m definitely getting into the fun part of the project. I spent part of the evening trying to add a servo to the front holo projector. It was a little more tricky than I thought it was going to be. I’d seen photos and vaguely remember a setup on one of the tables at C4, but until tonight I didn’t understood the nuances of the angles and forces need to move something with a servo, so it was frustrating and fun at the same time.

Most people seem to use the same basic method to move pie panels, doors, holo projectors etc. And that’s to convert servo rotation into a linear movement using a push rod attached to the servo horn.

I’d bought some random mini servos from Tower Hobbies a while ago (Hi-Tec HS-55), and a push rod/linkage assembly from ebay. Problem was the servo was too small to fit the rod attachments. I managed to improvise and this is what I finally came up with

Please ignore the kinks in the rod, it really should be straight, but I’d tried to copy what I’d seen at C4 and got it totally wrong 😀

If I was to do this again I’d probably skip the pre-made assemble and make something in acrylic and parts from the local hardware store.

I also created a short video to summaries and demo the new setup.

As I explain in the video it’s not perfect, and I need to affix the servo more permantely to the dome rather than using velcro and I’m not entirely confident the linkage to the back of the HP will last very long.

The good news the Hi-Tec servo is definitely powerful enough to move the HP and will probably work for the pie panels as well.

I also need to decide if I’m going to add some code to my micro-controller to automate random movement.

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Posted by Chris on April 29th, 2008 in Dome, Electronics, Events, Legs | 14 Comments

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Mounting Dome Electronics

I was getting tired of my disorganized electronics in the dome, so I made this little holder that mounts everything cleanly and is easily removed.

It’s just a piece of acrylic bent into a U-shape with an extra L-shaped shelf glued in the middle.

The various electronic boards are velcro’d into place for easy removal and the whole thing attaches to one of the dome ring supports.

Top: Syren10 Speed Controller (Dome Periscope), 12V/24V DC/DC Power Converter
Middle: Power Distribution Board
Bottom: 12 Channel RF Receiver

I secure the wires that run up to the dome to make sure I don’t accidentally pull everything off when the dome is removed

Please ignore the 16 gauge wire as well, I was running short of something lighter but didn’t want to make a special trip to the store.

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Posted by Chris on April 28th, 2008 in Dome, Electronics | 8 Comments

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A look inside the failed Pittman gearbox

I replaced the failed Pittman dome motor last night, and thought I’d post some pictures of the failed gearbox.

The pen tip is pointing to the failed gear in the center of the picture. The teeth are almost stripped flat.

And this is the new motor opened up and how the gearbox should look. Again the gear in question is in the center of the shot. Notice the teeth!

I’m not confident that it will not fail again, and I may need to look at an alternative. I’m hoping the issue was my failed attempt to use batting tape to line the dome bearing to help with traction, but the gear may have been slowly failing with the constant harsh stop/starts on such a small gear. I know of at least one other builder that had a Pittman dome motor fail in the exact same spot.

Posted by Chris on April 26th, 2008 in Dome, Electronics | No Comments

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