BrickBear

Sounds like good progress. I made some ground with the leg movements. I think the biggest problem I was having was the levelling aspect. Basically the push cam was not keeping the foot at the same level perpendicular to the ground. The next obstacle I’ve come up against is that now modified the cam is not lifting up the hip at the same time it starts moving it forward. Perhaps I have to delay the movement forward which in this case may be beneficial towards balance anyway. I saw on instagram that jk brickworks too the gingerbread AT-AT and created a rough approximation of the walk cycle. Albeit via a static base containing a mechanism as opposed to a truly walking vehicle.

New foot, more stable due to lower ankle pivot point. Less motion due to circular plate at top. Easy fix but not necessary right now.

My latest problem with the legs is their propensity to slide with the weight, this mechanism has the correct cycle but without that issue. I just need to figure out the front legged version

Ok, so i came up with an attachment to the shoulder/hip movement mechanism that works to shoft the weight of the battery box at the back and needs to be connected to the head. Which was much like how the OG lego walking at-at worked.

Yeah I need to have a play around with counterbalancing and fixing that snapping motion the front legs do

tada FYI I’m not holding it up, the balance is pretty good, unfortunately I had to lock the steering so I don’t think we’ll see a proper RC version, although time will tell.

Ok, so I’ve returned to the old bending function because I never had the problem with the bucking feet in that. It only bends a teensy wee bit but it’s noticeable enough. Should give plenty more room for the motors and battery box too. The legs aren’t too wobbly either luckily. 3 more legs and the motor then I can test it again. I think I get what you mean, I’ve had parts catch on others but i’m quite good at compact building and so not had too much of a problem.

ugh. So the xl motor kept coming loose because the strength of the surrounding structure wasn’t good enough so that’s a setback and so everything was getting out of sync (thank goodness for the gearbox system i introduced to resync stuff). I’m considering redesigning the feet so the ankle joint is actually at the base of the foot, it’s not canon but it might be more stable that way as the feet otherwise catch when they move forward. What matters is that it looks roughly accurate. regarding the leg bending i think i might try bending the body armour instead of the mechanism to give the illusion of a bent knee if I can’t come up woth a better alternative. I’m curious about my previous attempts with the sliding bending function but we’ll see.

Yesterdays progress included knee bending mechanism. Unfortunately a bit too wibbly so they buckle. Also i know the head isn’t quite secure, i need to build at better attachment This morning i’ve adjusted the motor so it isn’t part of the body shifting mechanism as yesterday under test the direction of the active motor was causing upset in the balancing mechanism. Going to unbend the legs for now i think

installed xl motor in back of AT-AT, you’ll notice the orange 2L beam can rotate to allow the motor to move such that the weight distribution mechanism can still work. Theres enough play in the gears to allow this. Although it balanced really well pre motor it’s clear that the head really does need to be attached to act as a counterbalance to the back. Once done then hopefully hopeful hopefully i can get it to if not walk then shuffle.

It’s @Aurorasaurus that has all the know how nelson.

Interesting. My goal is to offer instructions and because i like making books, i might make a sort of haynes manual inspired book on the process and mechanisms that contains the instructions too with handrawn bits and pieces too. It’s a whole creative project for me.

Ooh. So you’re selling the model as like sets or as a one off? Or just the instructions on rebrickable?

I’ll get a video and I’ll definitely be attempting leg bending again, I actually found a solution to the overlapping cycles, basically if you have a worm gear powering your legs you can give it half a bush of space on the axle to slide and that provides a delay as the worm gear will slide before turning the legs. I’ve also reduced the angle that the body shifts because it was a bit too much with the battery box, the big problem is the legs bending towards the raised leg and the feet catching, so i need to add the head as a counterweight and shore up the leg joints. Progress!

Happy May the 4th! So i’ve removed the bend from the legs for now. But i’ve been working on a mechanism to shift the weight of the walker as you can see the body is at an angle: It works quite well, although it still struggles to walk (the front toes seem to catch so i might need to tweak them) however it does not fall over which is an improvement. In conclusion we’ve gone from nothing to vague shuffling.

Altered leg for more squish (4 wide), offset by half a beam hole to ensure symmetry.

Promising but spring position might need adjusting so theres just a little more leverage force pressing down on it as the legs don’t quite straighten:

Somethings going down at Kurt Drive Yards:

Update on this, I’ve been working on the spring compression method to make it easier for the leg to straighten. I’ve made a diagram of what should happen and what shouldn’t happen. i think i need to take a look at my first design, i’ve been developing something that seems good but i think my first one where the spring was compressed by the pressure on the foot might be the smartest idea.

Progress update. I think i’ve found the final design for the spring bent leg, i’m going to attach all four and see if I can get it walking. (Probably not today though) edit: on further inspection the chances of this being successful may be slimmer than anticipated

I haven’t made much progress in the last weeks. Just fiddling when in passing. Must get back to it next weekend and that Facebook reaction certainly sounds good and suggests the current iteration maybe is worth pursuing.

So I decided to investigate some other solutions to the wobble and i’ve come up with actually quite a neat system. Basically I move the linkage that was originally connected to the cam to it’s own separate gear. That means I have one worm gear moving two gears, the first gear makes the hips move up and down, the second moves the leg forward and back. This makes the leg have a connection above the hip joint as opposed to below it and has significantly mended leg wobble. The caveat however is a new knee bending mechanism needed to be introduced. I tried a few things and managed to come up with a system whereby knee bend is initiated by a spring and when the foot is on the floor, the kneebend is counteracted by the weight of the walker pressing down on the foot. This means I need to order 4 more softer springs or figure a way to modify it so the spare rubber pieces can be used. The yellow axle would be connected to the ankle joint.

Progress update, I modified the feet further, now the feet lie flat and the rubber pieces extend out to the side, still providing friction, but with much more stability. secondly I have come up with a head mechanism, but it needs work. I intend to have the head act as a counterbalance and it seems to work well if it’s positioned just right however I think I want to shift the body weight left and right when walking as in a real animal too just so balance is not solely reliant on a complex head mechanism. I estimate that once fully panelled it will be around 40cm tall. note the second picture looks funny because I very badly clipped put the background and the head seems much larger than the feet cos of the angle. The right rear leg is raised off the ground by about 1cm. The head is currently acting as the counterbalance, you can probably see the mechanism by the neck, it’s a sort of seesaw that gets pushed up by the shoulders which turns a gear and that gear connects to a cam which moves the neck. I did power the legs a little and it showed some promise of being able to move. Lets hope for further progress.

No cheese wedges are the little plastic 1x1 triangles i’ve placed both of them angled face opposite one another on two plates on the 4x4 round piece that goes on top of the AT-AT foot underneath the liftarm that connects the “ankle” joint to the lower leg. I just call the rubber pieces “rubber pieces”

Yes, i’ve redesigned the feet so that they have grips underneath them now. This prevents feet slippage. And i’ve reduced leg wobble by placement of two plates topped by two cheese wedges facing each other under the part of the liftarm that joins to the foot.