BrickBear

Fair enough. I should be back up and running next weekend so hopefully I can continue contributing to the effort in the irl.

I think the problem lies in the weight balancing as it takes its rear steps. As you can see when it takes its front steps, the at-at leans backwards and the opposite when the back legs raise I think due to the angle of the legs. I don’t know if you’d be able to implement that. Also perhaps a properly filled out head would be helpful. And if you want to test your mechanism while adjusting weight I suppose you could try attaching balloons to the thing, using those to adjust the weight could allow you to determine how much you need to shave off. That all said though, it’s impressive that is indeed moving with the weight.

Ah! Yes, I misread it.

I’ll admit to not fully quite understanding how yours works, but it’s inspiring and like you say motivating to see someone who’s achieving successes in the small field of Lego AT-AT engineering. And I will say that your design has made me more cautious about the strain I put on my parts having been witness to things breaking on your model, it makes me question my use of hard springs. I agree our goals differ here and there. I’m hoping to get it walking outside if my designs remain having decent ground clearance. Also petition to rename the crank angle the crangle? 🙋‍♂️

I’d need an intact model first. Mines a bit bitty. I don’t have access to the Lego for another week so it will have to wait a bit too. I have come up with a mechanism to replicate the movement of the legs forth and back differences: The orange cam rotates and pushes the grey and white liftarms back and forth, the leg would in theory be connected to the grey one. Due to the shape of the white liftarm it is pushed further. So you could basically make two of these and rotate it 180, attach them together and have an accurate forward back movement. I managed to make it so they lift up and down while still accepting drive. I’m curious to build it and see if it works. The up down mechanism would require synching with the forward and back of course. The black L connectors connected to the dark 7L vertical liftarms are where the hip hinges.

Very nice Nelson. You may sooner reach the goal than me. My line of thinking is that if I can use a cam to push the leg forward and have both the knee and the foot follow the line of motion that will lead to the most accurate and stable movement. I also noticed something yesterday with the AT-AT’s gait. When the AT-AT moves, the legs are direct opposites in how far they move. So the front legs when stepping forward move out to the front as far as the rear legs move out to the back, the angle at which both move inwards is steeper. This gives me an idea which I’m just experimenting with in stud.io. Regarding lights try “light my bricks”. A very small and easy to implement solution. As they aren’t a part of the actual mechanism and would not need to be incorporated into instructions I feel it’s acceptable to include compact 3rd party lights in your own personal version.

Looks like you’re getting on a treat Nelson! I’m away from my Lego at the moment (working on a graphic novel) but I whipped up this brainwave I had in Stud.Io. I traced a line of how the at-at’s leg moved from some footage and figured out this shape of cam is about right for the forward and lifting motion. My initial problem was I was looking at the current unbending, single lift arm legs of my AT-AT and thinking the point of the knee was equivalent to the point of the foot This is the path the pin hole where the knee would be takes with the current setup, mind it was a little confusing as I took photos of my computer at different angles so it might be better, might be worse in reality, I’ll see if I can redo it with snipping tool instead. Here is the path an at-at walk takes at the knee and foot: the red line above is the current path of my actual physical walker. I would say I’m much closer with the brick link version. I can’t speak for Nelson but I can say I am nothing if not tenacious. And just think we’ll be making history, nobody has done this before, unless you count JK brickwork’s gingerbread AT-AT that has the right cycle but is stuck in place (the mechanism is in the ground). If successful I’m going to make a journal from the perspective of a kuat drive yards engineer with all sorts of drawings and such with instructions too if life finds me time for it.

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: