Lara's Lego H-015 Sentry Droid

[kresty]

Well, after being stalled for sometime, we've resumed assembly.  Nothing brilliant to show off at the moment, but the faux-wheels were tricky-ish.  

The Lego "balls" are almost perfectly sized (11 studs == 88mm, the "real" one was decided to be 88.9mm).  They're really smooth, normally having planets or stuff on them for some of the small star wars sets (the ships were in the middle of the ball).  

Unfortunately, they're not made in plain colors, so we buffed the asteroid field printing off of them to end up with black.  The attachment point is 4 studs at the pole (both hemispheres are identical).

So we've printed a part that fits the corner and has an inner sphere recess, with 4 holes in the middle for those studs.

And it actually fits pretty well, this looks like it'll work great!

[kresty]

So I'm wondering about where to stick the omniwheels.  Oliver stuck them in the area of the lego greeblies on the "real" droid, which requires cutting holes in his castings.  Since our greeblies are real Lego, we're not too keen on chopping out space for them.  



So I was wondering about bringing them "in", inside the corners of the Lego greeblies. Catch is that provides a shorter "wheelbase", which could make it wobble more when driving. Also, any unsmooth surface would amplify the rocking as the faux wheels move up and down further than the real wheels would. Which might make them hit the ground more often and make things like switching to a ramp or going over a door sill more complicated.



While pondering this, it occurred to me that a "staggered" placement would probably still be drivable and get the bottoms of the wheels a couple cm further from the middle of the droid, helping the wheelbase a little. I'm not sure any oddities of this position are worth the improvement in wheelbase, though I imagine it would still drive omnidirectionally. Not sure if the math would differ from normal though.



Obviously, we could also position the wheels somewhere between Oliver's position and the inside position. But it seems like if we were going to make a void, maybe we should go "all the way". His aren't really very visible in that position, so part-way doesn't seem like it has many advantages over Oliver's position. (Though maybe it'd be easier to cut holes if we only moved them out a little bit more.)

Any thoughts?

           

[kresty]

FWIW, currently the 3D model has the omnis positioned about 1/4" (6.5mm) below the faux wheels. I remember that the "real" droid didn't have a lot of clearance, but I'm not sure what's best. Thinking that maybe they could be adjustable.

[kresty]

Well, that's different.  Wrong show on your computer wallpaper Lara!

You can see from the photo that we've decided to put the Omnis all the way inside the Lego greeblies. We'll see how that goes...

[kresty]

Wow, it actually looks like we're *finally* doing something - after an 8 month or whatever delay.  Now we get to see if the new skirt actually fits over the Lego Greeblies!

And it does.  More pix because the cat might mess up the scale.

It's actually starting to look like something.  Whew!

Side view to check out the position of the omniwheels, and that the faux wheels might actually fit.

In particular, we want the omnis to be lower than the faux-wheels, which they are!  (This picture doesn't show that well, but they're about 1/2" lower than the omnis, which is probably about what we want!

This was "just" a test fitting. The corner strips aren't in place yet. But it was a huge relief. The outer bricks are merely to help hold the sides together until we're more finished.

[kresty]

This print was funny, so I just had to share.  We "need" little bands to hold the edges a little on the lower edge of the skirt, so I printed these strips.



But it slipped on the first layer (my glass bed has spring clips and I guess the head hit one and moved the glass)



Since it's only the flat backside and we really only needed it for the front connections, we went ahead and used them, but it was kind of funny. Especially since the error is so "perfect"

   
   

[kresty]

I've spent too long on this button.  While Lara's been printing and gluing the skirt parts, I've been trying to design a power button.

H015 Sentry Power Switch

I was mildly curious what "real" switch it was, but I wasn't able to figure that out.  But the uniqueness bugged me enough that I thought it'd be fun to capture that idea in Lego.

I found a power button with enough amps, but it's a tight fit between the waist and the Lego Greebles.  Also it's throw was only about 3mm, but I wanted more like 10mm so I could have a black & white Lego pattern as a nod to the original.

So I printed a lever that the Lego could trip.  Since the lever's longer, it goes up & down further than the button.  It ended up being a lot of parts.  The lever, the housing, a pad for the lever to push the button, and a cap at the end of the lever for the Lego to attach to.  (And a TBD mount for the housing)

It needed a little sanding, but amazingly it pretty much worked the first time! It does what I wanted, showing some B&W detail when "OFF", and pretty much hidden when closed "ON".

When turning it off, I do have to pull up a hair on the Lego to get it to click so I can push it back to on later (otherwise it won't latch when pushed), but pretty much it does exactly what we want it to.

[kresty]

Making some progress.  The Lego Technic holes are perfect for a 5mm LED.  These are fancy Pololu addressable LEDs.

https://www.youtube.com/watch?v=b1dw9oDK...e=youtu.be





I had decent video of the back/right, and the very short bit I saw of the left transitioned at the same time as the back.

Front is solid blue
Back/Left blink red at about 2hz (seems slightly out of sync with right)
Right counts down from 3 in binary if Green is ones and Red is twos @ about 4 hz.

(Or counts up if you consider blank to be one).

At least at this rate we'll have electronics by the time it's built! (ETA ECCC)

[kresty]

(new stupid YouTube channel because we were informed that without a higher # of subscribers and views they'd treat us poorly, so hoping we can consolidate the droid channels)

[kresty]

And a test of the holonomic drive (which actually happened Saturday, before the LEDs, oh well).

Sorry, video is pretty rough. Droid runs well. Cat finds it a bit too interesting! (At the end I parked it and he's climbing all over it).