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

Picture_027.jpg

 

Sides

 Picture_020.jpg

Picture_024.jpg

 Front

Picture_025.jpg

front and hip

Picture_031.jpg

 TOP

Picture_034.jpg

Servo brackets all the numbers arein cm 

Picture_035.jpg

 

 

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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

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

 Could we get some more details please?

What kind of circuits, what kind of actuators, Du you have any consept drawings, and some decent pics with size reference would be interesting.

/ vzz-clck-"Maneuver"

Right now it has and arduino am hoping to change it to 2 1f88 in bus

http://jallib.blogspot.com/2009/01/step-by-step-building-i2c-slave-with_17.html

^^

One visible servo appears to be a Futaba S3004, a standard sized with 44 oz-in (3.2 kg-cm) torque at 4.8 volts, 57 oz-in (4.1 kg-cm) at 6 volts. You'll probably find that these won't support the weight of your robot. And that the plastic gears will tend to strip out. I don't know if you have other types of servos at use at other joints, but it might be worth it to look at maybe HiTec HS-645s to start. There has been disucussion on a Tower MG995 servos here, that have some good torque but can be dodgy. I'm thinking through my own biped, and will probably risk the cheapy high torques or a close servo.
ich!! it weights 1kg am hoping that it will suport what do you think  (am cashless) :P

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.