BrickBear

More progress. Same gearbox connector to front and back as in other prototypes.

Very nice. I understand what you mean about the weight. I guess it’s why people tend to say it’s an impractical concept. Like obviously when it comes to things like the elephant or paracetherium we know as animals they would naturally be able to distribute the weight via micro adjustments in their body. With a mechanical vehicle it’s a bit different and therefore frustrating and fiddly. That all said, I’ve done some work recently on the hips. You can probably hazard a guess as to how they work from the image. Basically the orange liftarm rotates pushing the L liftarm and the white curved liftarm upon contact. Creating a forth and back movement with a short stride inwards than outwards as in the real thing. The universal joints allow for the hips to move up and down while powering the orange cams.

Noice noice noice. Very impressed. It’s neat how the head starts moving back towards the other side right before the other leg lifts. Been working on the hip mechanism myself. As always trying to get that specific movement in. Looking forward to see progress!

I see, well I think the one you’ve got is very good and worth me stealing if I may.

I’ve still not made any progress myself. Various art opportunities in the way. Maybe this weekend I can get back to things. In the meanwhile have you seen the official Lego motorized AT-AT head movement mechanism. It’s simple yet effective (albeit timed for the inaccurate walk cycle. Maybe check it out and tweak the timings so it works for the actual AT-AT gait?

One option for the head might be to make it slide along a beam with the lifting of a leg, so essentially it moves by its own weight on a tilting beam.

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.