BrickBear

That is useful to know. Alas I cannot test your theory this weekend due to being ill but I shall stare longingly at my model from my bed.

Yes, basically the (soft) spring(s) would be half a pin hole longer than the current pivot point for the foot when fully extended. This would give the illusion that the foot has touched the ground when the next foot lifts. As the leg moves the spring could then contract to the position that you currently have the feet in (adding a stopper to prevent it contracting more) and that may well solve the problem of the foot not quite touching the ground upon its step forward, being the soft kind of spring as well it should not place too much pressure on the ground if any to affect the balance as the weight of the walker would compensate.

I reckon you could fix the cadence problem (i.e only one foot off the ground) not by tweaking the gearing and mechanism but by adding a spring or two to each foot. With the spring pushing the previous foot forward a little it should in theory touch the ground as the next foot lifts, giving the illusion all is in sync. As for my AT-AT’s balance it’s more the issue is that is has the potential to fall forward left or forward right if the weight isn’t on the feet on the ground but i’m hopefully going to remedy this with the seesaw mechanism.

Brilliant. Looks very exciting.

So I actually came up with and implemented a much simpler solution for weight distribution on the front feet this morning. (The back feet lift fine already because the head leans the weight away from them) It’s basically all about the heads attachment system. So above the front two legs “shoulders” are a sort of see saw mechanism. When one front leg lifts up it causes the seesaw to rise on the side of the raised leg. The head which is connected to an axle on the seesaw then rotates toward the front leg that is not raised because of weight and gravity. Because the see saw is moved directly by the legs, the weight on the seesaw created by the head is transferred to the leg that is not raised and so stability is achieved. It’s so simple and such a relief to have achieved this. Also @Nelson you might find this solution interesting.

And then I said but back leg first, the camels is reversed, I acknowledged that.

Ooh that is clever. I’ve watched the first an unhealthy amount of times. It’s interesting how the camel lifts at the shoulder at its front like Nelsons. It’s definitely the same gait (albiet back leg first then front leg)

Looks like a brilliant start, I have to admit I’m somewhat jelly of the stability of yours.

A new year, perhaps a time for new solutions. Here’s to achieving our AT-AT ambitions in 2025

Thats just where the steering pivot point is, a turntable is a stronger pivot piece than an axle or pin.

Whose a good boy? I realised I couldn’t make it walk without the head being added as that’s the heaviest part. (Note the head seems bigger here, it’s just perspective) Lifting the feet with head acting as a counterweight. What i’ve noticed is that the feet do still slip a little on the ground with the head added. But the springs are really good at holding the weight. I also have new batteries which really upped the power of the xl motor. My main problem now is the head function, I need to have the head rotate based on the movement of the legs so it remains an effective counterbalance. Still, the model has never been so stable!

Ok so I also introduced stoppers to the front. This has significantly improved balance as the legs are nwo limited to the movement they should have been. Also strengthened the central pivot for steering. Everything has been reinforced basically. Need to see if it walks now.

@Nelson First of all may the best man win. You raise a good point about the leg raising I could try adjusting the positions of the cams by disengaging the middle. And yeah i’ve checked out Philo’s home been using it since I was a kid. Regarding the weight of your model, do you think it might be worth sacrificing certain levels of detail for functionality? Like maybe you could get some prints or stickers for detail on larger plates?

Some good news, i’ve begun adding the legs and implemented various features to counteract some problems I was having. One problem I was facing was when placed the legs would slide (as if doing the splits). I had this same issue on the previous one which is why I remade the chassis in the first place, I thought it was a suspension issue but To fix this I merely needed another 2x1 beam to be inserted onto the existing cam shaft to act as a stopper which could have been done on the old chassis. But nevermind, this chassis is stronger so it’s progress either way. Referring to @Nelson suggestion to take the weight off of the back leg diagonally opposite to the current leg lifted up off of the ground I have found that now without the “splits” motion occuring for my model that this is a natural byproduct of my mechanism design anyway. As a result upon adding the other legs it stood perfectly even with one leg raised. I just hope the torque of the xl motor is enough to move everything once the bodywork is placed. I’ve defrictioned joints, modified the suspension all to reduce resistance on the motor. I believe the XL motor can take up to 14nm according to wikipedia 9.8nm is roughly enough for a 1kg weight to be lifted a metre. I’d be interested to know how much resistance towards the motor the hard suspension provides in terms of weight. (I guess that would be how much weight the spring can hold at full length under load?)

New version moving, lossy gif. No legs yet.

Ok so I’ve nearly finished modifying the frame. I’ve added the gearbox mechanism to adjust the front and back cams independently of each other, i’ve added an L-Motor and repositioned the grey technic frames one hole over as stated last time. one problem i’ve run into is the l motor isn’t really powerful enough with the resistance of the springs having increased. So i’m going to upgrade to the xl motor. Otherwise, the mechanism is now stronger and more polished than before and the positions of everything should be enough to support a battery box, steering motor and ir reciever as well as bodywork. That is very impressive. I’m guessing you’ll have to upgrade to a thicker gear if possible?

The real reason is much simpler, I have many black pins and fewer grey ones in my main technic boxes so I like to use them for things where it’s absolutely necessary for the frictionless stuff.

It’s not quite finished yet, I have to adjust some stuff for it to move but once done i’ll make a gif.

So this is what I worked on today: It’s essentially a redesign of my walker iteration’s chassis, reinforced and the suspension repositioned to take a heavier weight. The bend in the middle is also more stable than it was before. Few bits to finish adding and a tweak or two. But this should provide me with a better foundation going forward and has refreshed my mind on the project after being away from it. The previous one for comparison:

You’re doing gods work. Meanwhile i’ve finished my course and the house decorating is done so I should have a little time for development at the weekend. I’ll consider your discovery on the leg lifting situation when working on it.

Looks promising. Certainly try an xl motor. Do you think a medium + hard spring might be useful for push down? There’s also the question of linear actuators. They can do some interesting stuff: (note video not mine)

Sounds good 👍 As for the skateboard mechanism…well maybe something like this?

In a similar vein I was considering adding counterbalances that swing left and right. Basically you’d have the hips going up and down and then you’d have each hip attached to a see saw like mechanism and when one leg lifts up it would seesaw the weight away from it to the other leg. So left leg goes up, seesaw left side goes up, weight leans right. I also had another idea which was to make the legs move forward like a skateboard. Basically when the skateboard platform leans to the right, the front left part of the axle moves forward as if to steer to the right (but you could modify it so the leg stays straight) and as the body would be leaning right it would act as a counterbalance to the left leg moving forward.

@Nelson Unfortunately I don’t have a video of it yet due to balance. I could try powering it while holding it up just above a surface so that you can see it moving. Initially I did try to use cams keep the legs down, however it was before I had the linkage connection right so it seemed to not be stable enough and the timings made it not as smooth as I liked. However now I realise the linkage position had to be a certain way. if you can work out a way to do this successfully timed I’d be very interested as it may turn out to be more successful than initially thought.

Unfortunately haven’t got round to anything yet apart from some mental visualisation of necessary changes and bricklink scouring. We are having rooms painted this week so need to keep things tidy and stuff has to be moved about to accommodate. But I was looking at my model today and realised that while my front right leg is raised that the right back leg begins raising too at a certain point. So i’ve got a little configuration necessary to counteract that, speings I think in the leg where the feet connect, not enough to cancel out the feet being lifted clear off of the ground but enough to prevent unwated liftage.