Is there any pictures, videos or projects on 3 legged robot? Hex and biped are very common. Too common indeed. Anyone up to the challenge? 
I’ve been wondering about that one too.
Seems like one hell of a challenge to get it balanced 
Hell, i will take your challenge if you fund the project 
I accept paypal ^^;; Send me like $500-1000 and i will try my best to get it working
Seems that you would need to balance it on two legs whenever the third was in the air taking a step. In order to do that, you would have to start from an inherently stable tripod stance, throw the weight over to a balance on two legs, reposition the stepping leg, and then settle back into a tripod. Repeat at 120-degree angles for the other two legs. Lather, rinse, repeat as necessary.
You might be able to shift the center of gravity sequentially among the legs with a slowly spinning weight, such as the battery pack, though spinning implies some sort of commutator or slip-ring arrangement for getting power to the electronics.
I don’t see why it couldn’t be done, though it seems like the gait would seem a bit awkward, if only because we don’t see many examples of three-legged locomotion around in nature.
On the other hand, what is a hexapod if not a pair of tripods that share a common chassis and move in concert with each other?
might be some value in studying the tripod gaits used in the war of the worlds movies. they probably spent some amount of time with that since it would impact the movies… I want to say believe-ability but, uh, you probably know what I mean.
Bah, it could be worked out pretty easily if you have good servos and SES stuff (I only have 6 422’s…) 
I have decided to accept that chalenge do you want it to do anything specific other than walk?
I was thiking that mabey it could walk by fliping it self completly over 
I think I can get the physics to work kind of like the bipeds’
I was close to building a 3 legged bot recently but didn’t because there weren’t any kits and I didn’t feel like machining anything as I live in an apartment and don’t have a shop right now. I wonder if something can be done using the SES though?
I think it would look awesome if you could do it. The reason they picked the 3 legged design in War of the Worlds was precisely because it doesn’t exist in nature - they wanted something was as alien as possibly. You can study the gaits they used but I don’t think they have many scenes where the just walk very fast or fluidly at all. Regardless, you would want to start out slow anyway to get the balance down.
yeah… they walk with tentacles, and physics would say there would be on the floor a while bake 
I was sitting up last night playing GT4 and was thinking about this a bit more, going through my head trying to figure out how to balance this proposed 'bot properly. I’ve always heard that bipedal animals are a rather inefficient support/propulsion model, as a considerable amount of energy and processing must go into balancing the CoG. This would be resolved, to a certain degree, by having a tail.
Seen in most primates, a tail represents a multi-function tool that humans could really find useful. They assist in balancing (act as a third leg to form a tripod), can grasp objects (how often have you needed a third hand?), and combinations thereof (grasping an overhead limb to pull them up, while holding something in one hand). Anyways, enough about our shortcomings…
As mentioned previously, I think the key is to keep the robot balanced on two legs as much as possible, leaving the third to provide the propulsion, push or pull, or to perform some action. This could be done by:
- shifting weight over the two planted feet
- designing the feet to distribute the weight properly so that no weight shift is required
In the second example, the rear leg could have a foot design that is much larger, so that when one front leg and the rear leg are planted, the robot can lift the other front foot without falling over. Maybe something along the lines of Johnny 5, bent over forward, using his arms as legs?
Just my CAN$0.02
Ross.
Maybe something like a beaver’s tail, but then would it really be a three legged robot? The number of legs a robot has implies they are all of the same basic type, perhaps with additions at the extremities. My Walk 'N Roll bot would be an example of this with grippers on the ends of its two front legs.
Maybe the third leg could be the same type as the other legs with a flatter and wider foot. like a beaver’s tail, so it could help in balancing better while walking.
You could throw the third wide foot leg forward and then bring the other two legs forward one by one while holding the bot’s weight over the third leg.
8-Dale
Check out my recent post in the Projects forum (sorry, I dont know how to create a link to reference it). A proposed gait is roughly shown here:
www3.sympatico.ca/rkleonard/triped/
Regards,
Ross.
I’m not an experienced roboteer, but it seems to me the obvious approach to take would be start with the round hexapod body with 3 equally spaced legs, and just move one leg at a time in small, fast increments. Actually, I would guess a small bit of overlap in the leg motion might work out and could smoothen the gait.
Anything more complex than that would definitely need gyroscopes.
Not that I think it’s a good idea … there is a reason we don’t see 3-legged animals, tables, etc. It’s not at all stable.
Oh, and the vehicles in the War of the Worlds movie have 3 legs because it’s written that way in the book.
-Adam
Three legged animals, probably because three-legged locomotion is inefficient and difficult, but three-legged tables, stools, etc. are extremely common. This is because a three-legged arrangement for a static object is much easier to achieve than with a four-footed one. Look at the number of wobbly tables that rock back and forth on two feet, while alternately achieving some amount of stability using the other three. As long as the center of mass is within the triangular footprint defined by the three points of contact with the ground, a tripod is going to be stable.
Triangles abound, both in nature and in engineering, largely because of their inherent stability. They don’t appear often as a form of locomotion, though.
you could get a three legged robot 2 work. lot of code and mechanical parts needed though. there is a 1-legged hopping robot. three legs is about that unstable.
One word… Kangaroo! lol
Although it’s not literally three legs, but it’s three apendages used in locomotion.
Great point … reminds me of a documentary I saw on Thylacoleo, a giant prehistoric marsupial lion, which also was able to use its tail to walk on 2 legs like a kangaroo.
So when is the robotic tripod marsupial kit coming out? 8)
its not too umstable, ui just need 2 smaller feet like a biped with 1 leg inbetween with a large wide foot on it , 2 small feet move forward while it stands on the large foot and vise versa wen the big foor moves forward