Let's Make Robots!

Problem with hexapod

Hi, I'm new here and I'm not so used to forums so if I'll make mistakes posting, writing etc please forgive me and help me to find the way! :)

I also have to say that I'm not English so forgive me for my English or if I can't get something!

So... Let's talk about my problem..

I have built a 2DOF hexapod (should I post some photos, right?) using Arduino, 12 parallax std servos( Parallax Std Servo ) and building the body by myself. So, putting them in parallel I should give them at least around 1700mA and 6V.. Right? Because now I am no more shure of anything!.. In fact giving them 5A and 6V my poor creature walks, but dragging its "back" on the floor!.. I tried to recharge my "huge" battery and it made some steps as it should do normally but after that it turned again to drag its last 2 legs.. It seems that it has no force enough into this legs to hold the wheight..

I should explain better what I mean with "drag" with a video so I'll do it tomorrow! Meanwhile please suggest me something about what I said before! Thank you beforehand!

Famous quote: "LMR users, you're my only hope!"

[UPDATE]: Attached video so you can see it working! (Sorry for quality, I don't have time to make a better video <=D )

[UPDATE]: Attached second video about the problem I descibed. Note that the rear servos are unable to hold the wheight while the others have no problem!..

[UPDATE]: After a slimming therapy (from ~1.7kg to 1.380 kg, without arduino and battery) I am proud to present you the new design of my creature that allows it to walk autonomously with the battery on bard too!!! Watch the video!! =))) (it's better to download it and watching it on locale)

So the problem must be the power or the torque! (but I am inclined to think that the torque is enough..) Now I have to make it turn around!

Video0029.avi293.63 KB
CIMG4335.avi1.93 MB
CIMG43410.avi1.33 MB

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assuming you have all 12 servos working at the same time:

from the datasheet you have

"Maximum current draw: 140 +/- 50 mA at 6 VDC when operating in no load conditions"

 worst case cenario, with no load

 ( 140 + 50 ) * 12 = 2280mA

best case

( 140 - 50 ) * 12 = 1080mA

but this is ALLWAYS with no load

with load you can go way over the 5A