Let's Make Robots!

METAL REX

Walk
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This is my second proyect i decided to make a biped ( in emulation of the metal gear saga )

the circuit that controls the servos consists in a pic16f88 and i also use the arduino decimilla

am going to post the drawings and schmes in a couple of days

 

any tips with the walk sync or any other subject are welcomed.

the the mesurements are in cm and they where made out from the servos

there are 2 kinds of servos in this proyect futaba 3004 and hi tec hs-311 (standard servos)

 

Picture_009.jpg

 

Ok here are some better pics 

ANKLE

Picture_017.jpg

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Sides

 Picture_020.jpg

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 Front

Picture_025.jpg

front and hip

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 TOP

Picture_034.jpg

Servo brackets all the numbers arein cm 

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The reason THIS project came to a standstill (!) was that the servos (similar to yours) didn't have enough ooomph to shift a 6xC cell NiCD from left to right on the end of a lever 15cm long. It's not just about weight. My servos would easily lift the motors off the ground on a shorter lever. That said, the legs worked quite well and it weighs a little over 1Kg. The only thing is your legs seem to be longer. Again, it's a leverage thing.

Look at the horizontal leg piece, has a servo on each end, guess it could be called a hip joint to knee joint. That one section appears to be about 4 inches (10 cm) long. That is essentially a lever arm that has to hold up a good share of the weight of your robot, the other leg with it's 5 servos, plus the 2 above, plus the body, which might add up to 0.8 kg of the 1 kg estimate. The servo is 44 oz-in or 3.16 kg-cm, so it could lift 0.8 kg only on a lever length of 3.95 cm, not the 10 cm of leg you have. To lift 1 kg on a 10 cm leg length, you'd need a 10 kg-cm servo, at least. And this is not considering the weight of any battery, I'm guessing. It might be best to look for servos that have at least 10 kg-cm for your robot, at least as far as lifting joints are concerned.

I think BOA had some problems with these, but clcheunghk had success so I still might try the TowerPro MG995.  At least when they get back in stock.

Definitely you need at least MG995's power to drive this robot.

Except that the MG995 was very shaky and unstable. But I heard a rumor that the new version fo MG995 fixes the problem...not yet verified.

 

Hey I like the photos! Gives it a sorta sci-fi like quality I think! In the 2nd photo this looks like a mech-like thing from above? Walk-sync...oh-my! That could be a big problem, especially with a biped. Are you planning to have some sort of active balance system (gyro, accelerometers)? I think I saw someone here in LMR do a self-balancing segway robot. You might try "self-balancing" in search.

 

Thanks.

yeha am going to look into the LMR ^^its going to be fun the walking sync so far all it dose is fall :P

i will keep posting

It's very hard to see with the flash reflecting off the background. Maybe you could take some pictures in a different location so we could see it better?
jeje yeha sorry  am going to adjust some things and ill be back with better pics and details
?

I've got no sense of scale here. How big is this thing? it looks absolutely massinv ein the first and third photos, and I'm just not sure in the second.

Mike

thanks for the advice i place some dimensions