Bipedal Chicken Walker

[ultimatekiller]

Greetings!!

I am now a Final Year student and i m planning to make a bipedal chicken walker. Something like ED209.
Can anyone guide me on this? I mean if you got any reference, please post it here... thx

 

[Hank Fletcher]

The electronics are easy, it's the mechanics that are tricky. You need to think carefully about the balance of your robot, how the robot will balance throughout the entire cycle of its movement, and how the robot will balance when that cycle is interupted during stopping.

No doubt you've looked up "chicken walker" in wiki already, but there's not much useful there. Note, though, that the inverted knee on birds is actually an ankle - kind of helps you put things into perspective.

If you ask me, the biggest downside of the prevalence of computers as a means of entertaining children is the negative impact it's had on the production of proper toys. You used to be able to get all kinds of clock-work toys, and amongst them were a variety of walkers. The reason I bring this up is because there use to be a lot more of things like these about:
https://www.dannabananas.com/?q=node/28
This is one way of solving the problem of balancing a walking robot, in my opinion, one step evolved beyond having a roller-skating robot (where the legs move, but both feet are always in contact with the ground).

Whether you go with the solution of the wind-up toy or not, you'll have to determine how your robot will be able to balance on one leg. What you can't tell from Robocop or Star Wars is how the robots in those movies would balance on one leg. Really big feet are one thing, but unless they're designed like the wind-up toy, there's no way to accommodate the shift in the centre of gravity when either foot is lifted. The only way to accommodate heavy legs in robots properly during motion is the same way humans (and other bipedal animals) do it, and that's by moving the torso and arms to off-set the resultant change in centre of gravity.

So, if you want to make a walker, you want big (but not heavy) feet. And the feet should be designed to overlap each other in the middle, so that the centre of gravity of the robot is always directly over the part where the feet overlap. With that concept, you could theoretically make your robot as big as you please, although how stable it will be at any given time will be determined by its height in relation to the width of the overlapping part of the feet, and the degree to which the moving feet change the centre of gravity (i.e. even if the c of g is still within the overlap, if it moves a lot, or even outside, the overlap, the robot will become unstable).

That will get your walker moving in a straight line, and it'll probably do okay backwards, too. But how do you change the direction of a robot with overlapping feet? The way I'd do it (and I would do it, if only I had more time) is to have a knee, or an ankle, or whatever you want to call it, some kind of joint half-way up each leg of the robot. Each knee would be a fairly high-ratio gear motor. As one foot is in the air and the other is directly underneath it, the knee of the bottom foot twists the rest of the robot in the desired direction. The challenge with this is making sure that the centre of gravity remains balance during the twist, and that the design of the overlapping feet can accommodate the maximum change in the angle between the feet, i.e. so that when the other foot comes down during a turn, the robot doesn't step on its own toes.

 

[ultimatekiller]

thanks for the information!!
i already went thru the net and searching for the mechanical design of a bipedal chicken walker but fail...
anyone here can help me on tat? or do u hv any reference?