Metal Skull Robotics Hexapod Project

Hexapod Robots

Re: Metal Skull Robotics Hexapod Project

Postby Matt Denton » Fri Jun 27, 2008 7:58 am

Hi Pete, welcome to the forum!

You should probably start a new thread on your octaped project within the octaped category. :)

As for servo torque, you need three variables to work it out:

    (X) Distance from the tip of the foot, to the center of the COXA servo spline while the robot is standing, a bit if trig should tell you.

    (T) Torque (Eg, 3kg/cm which is 3 killogrammes of force at one centimeter from the centre of the spline)

    (C) Number of legs in contact with the ground at any time, for a hexapod worst case = 3.

    For this example:
    X = 100 (mm)
    T = 3 (Kg/cm)
    C = 3

    Total lifting capacity = (T*10*C) / X = (3*10*3) / 100 = 0.9 (Kg)

Bare in mind that some cheap servos are not properly rated at their stated torque, also, if you drive a servo at its maximum capacity continuously, it will probably get hot.. and sometimes die!

Hope this helps
Last edited by Matt Denton on Fri Jun 27, 2008 6:02 pm, edited 1 time in total.
Reason: Edited formula
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Re: Metal Skull Robotics Hexapod Project

Postby MetalSkullRobotics » Fri Jun 27, 2008 10:16 am

Like I said in another topic I’m aware that the robot probably won’t work (calculations show that it should be possible, with a little margin, but that are the calculations, most of the time they won’t apply a full 100% on reality). The reason why I use these servo's is because they are cheap, I can build the hexapod around it and start working on the algorithm. Because this is what concern me. If I get the leg movement right or if I think I will be able to get the algorithm and programming correct i will invest in better (12kg) servo's which will be able to let the hexapod walk easily.
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Re: Metal Skull Robotics Hexapod Project

Postby MetalSkullRobotics » Fri Jun 27, 2008 2:32 pm

Today I designed and build a small electronic circuit which will control one leg of the hexapod. Its fitted with a attiny1320.
Image

I will soon begin on the algorithm for one leg.
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Re: Metal Skull Robotics Hexapod Project

Postby cyberdead » Fri Jun 27, 2008 5:42 pm

Sorry, i didn't want to make mess in your topic, so i took out my picture, this is your topic :P and soon i'm going too open a topic off my project. But now, just wanted to know how other people calculate, their needed servo torque, i'm going to recalculate with your solution too, and i will see what it shows, thanks for help anyway.

P.S.: your robot is really cool :) i have to find a CNC specialist...
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Re: Metal Skull Robotics Hexapod Project

Postby Matt Denton » Fri Jun 27, 2008 6:03 pm

cyberdead wrote:Sorry, i didn't want to make mess in your topic, so i took out my picture, this is your topic :P and soon i'm going too open a topic off my project. But now, just wanted to know how other people calculate, their needed servo torque, i'm going to recalculate with your solution too, and i will see what it shows, thanks for help anyway.

P.S.: your robot is really cool :) i have to find a CNC specialist...


Cool, it would be good to see more octaped action! look forward to reading more about your project.
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Re: Metal Skull Robotics Hexapod Project

Postby MetalSkullRobotics » Wed Jul 23, 2008 6:05 pm

Today I cutout all the parts for the hexapod. They are at the powder coating but I’m hoping to be able to post some pictures tomorrow.
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Re: Metal Skull Robotics Hexapod Project

Postby MetalSkullRobotics » Mon Jul 28, 2008 7:40 pm

The powder coater had some problems. So its bare metal!
Image
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Re: Metal Skull Robotics Hexapod Project

Postby Matt Denton » Mon Jul 28, 2008 9:06 pm

Looking good!

Why do you powder coat instead of anodise, is it cut in steel?
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Re: Metal Skull Robotics Hexapod Project

Postby MetalSkullRobotics » Mon Jul 28, 2008 10:45 pm

Its steel and I dont have connections to a anodizing company. I did some other parts myself but they all get a slightly different colour.
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Re: Metal Skull Robotics Hexapod Project

Postby jaspinall » Wed Jul 30, 2008 8:04 am

Very smart :)
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