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31
Mechanics and Construction / Re: My Advanced Realistic Humanoid Robot Project
« Last post by cyberjeff on July 29, 2015, 07:41:14 AM »
I think both of those suggestions have HUGE merit and are very exciting possibilities.  I thank you both for bringing them up!  This vacuum neoprene idea and the Nitrinol wire idea have my attention.  Maybe one of them can be a plan b?  I'm already all in with my existing servomotor and pulley system plan having already bought a lot of what I need, already tested and done proof of concept, etc.  If you brought this up a year ago I might try it, however, I have to at least give the way I have been planning for over a year a try before trying anything else ya know?  I don't see why the way I am planning wont work.  Also, I agree it will be WEAK.  I can upgrade to more powerful higher voltage motors later though if I get more $.

One of my concerns with Nitrinol which I have looked into in the past is I haven't seen many projects using it and it isn't widely available from what I've seen.  It is very experimental and expensive and could have a lot of complications in terms of heat and electrocution possibilities... hmmm...

If you have proof of concept then you should run with it. The muscle wire is expensive and I think may be too slow and energy inefficient. The vacuum idea would require building things that are not off the shelf that have never been done. The advantage that air, or vacuum has is that it has energy storage, you can get a huge jolt of power and then wait for recovery. In my mind this is similar to the way most people use muscles.

I have given some thought to your idea of bands and servos, not that I wish to copy your project, but rather use it for a flexible spine. The bands would run through the spine and then outside where they would be tugged on by servos. Assuming the spine returns to a straight position, the curve of the spine with one servo could be modeled on a quadratic bezier. I would need 3 servos.

Since you have no flesh your robot could be relatively light, reducing forces needed. I think you may need to compromise between speed and servo size or by setting your pulleys as a force multiplier, probably you have already done that.

What are you casting with? How is  the weight?

I'm making my simple little toy out of cypress and find the skeleton weighs a small fraction of the total. I suspect you may have substantial weight.

Good luck to you and we await to see your progress!

32
Mechanics and Construction / Re: Exoskeleton design
« Last post by cyberjeff on July 29, 2015, 07:13:22 AM »
Humans make ground contact on the balls of their feet. They belong to the plantigrads:

https://en.wikipedia.org/wiki/Plantigrade

You happen to have a working model that you can take for a test drive whenever you wish.

Walking is not stable it requires momentum and dynamic balance. Balance can be done shifting arms, hips, torso or applying forces on the foot in the proper direction. The corrections are minute but necessary.

Humans are capable of an enormous number of gaits, all requiring micro corrections.

I've been working on a 4 legged digitigrade. I'm just  in software at the moment waiting for more servos. 4 legs is easier than two as the corrections can be done by one of the feet, but it  is still involved.

I'm curious as to how you program the gaits, how do you do  that?

I've broken this into limbs, and the limbs are broken into the significant joints with the rear  being different than the front. Unlike the way animals process their muscles my robot must work on the servos setting angles rather than forces. There will be a feedback process from an accelerometer/ compass and pressure sensors on the feet which I will write later. The gait is broken into forward and back strokes with a cubic bezier describing the motion of the servos for each servo. A cubic bezier requires 4 points to be set, so, for one step, with each limb having 3 servos that is a total of 96 points for all 4 limbs. Fortunately this is relatively easy to get a starting configuration and the left mirrors the right with a time offset.  How others do this, I have no clue.
33
Mechanics and Construction / [Advertisement] New 80/20 Mounts at ServoCity
« Last post by ServoCity on July 28, 2015, 08:31:43 AM »
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34
Mechanics and Construction / Re: Exoskeleton design
« Last post by mklrobo on July 27, 2015, 03:38:04 PM »
 ;) Hello!
I have not played with the software your are describing. I just draw a free body diagram, and go experiment
from there, one the intranet is exhausted. There are other posts that may help you. I am planning a
evolution of walking members, so I can think over time, which one is the best. What parameters are you
facing to work with?
35
Misc / Wanted to buy: 1st generation iRobot Create roomba 4400
« Last post by erin on July 27, 2015, 10:45:46 AM »
Hi all  -

I'm looking to buy about 5 of these robots, from $100-$150 each depending on which accessories you can provide.  I will also pay for shipping to NY.

Contact me at erin.marie.gee at gmail dot com - I'm wanting to turn them all into a little fleet of musical robots, I already have 8 but I would like 12.

Cheers,

Erin
36
Mechanics and Construction / Re: Pan/Tilt joint
« Last post by mklrobo on July 27, 2015, 09:04:52 AM »
 :) Hello
I have bought the Axon II. I have worked through most of the problems you may encounter with them.
and have posted the resolutions in the Misc section in this forum; Analyzing the Axon: Coding, Construction, and Contraptions.
When you buy the Axon, they are not like the other MCU's on sale. I am finding it a challenge to program
one, after I have overcome the first obstacles. The up side is, once you download the AVR 6 software,
you can program any Atmel MCU series, (theoretically). The Axon is the "portal" to a larger world,
because most of the Atmel processors are in everything! I found a Atmel mcu in a digital Watch!
Good Luck!!!
37
Electronics / Re: Problems with MT8870 DTMF Decoder
« Last post by mklrobo on July 27, 2015, 08:56:05 AM »
 ;D Hello!
I would offer an opinion, where permissible;  :)
I usually divide a project into modules, where I can troubleshoot/repair quickly, where needed.
I would get a audio amp kit from Velleman or sparkfun, to deal with the audio. this way, you
can get enough audio with no possible dropout. The DTMF frequencies are from 697 to 1633
Hz, so you should not have any frequency roll off on the audio amp. It does take a certain amount of
time for the chip to identify the tone; no less than 120 milliseconds, I think.  :-\
In regards to an Oscilloscope, I would recommend the Velleman PC oscope, PCSGU250 -
it has a oscope to 12 MHz, a function generator, a spectrum Analyzer, a transient recorder, and
a bode plotter. Who could ask for more, at a meager $150?  :o
You can take pictures of your waveform, to analyze later, or pass to other techs for their advice.(?)
Good luck!!!   ;) :) :D ;D
38
Misc / Re: Meccano Meccanoid
« Last post by mklrobo on July 27, 2015, 06:08:55 AM »
 :) Hello!
ANY  robot is cool!  8)
It has some big eyes!  :o  The better to see you with!
I will be interesting to see how the knew bend, with it
moving with tracks on the feet. It seems to be in the neighborhood
of 4 feet tall. Small frame would indicate weight bearing is low, so it
fall into the category of office assistance. May be able to assemble simple items
in an ergonomic station. Potential is there!!   ;D
39
Misc / Meccano Meccanoid
« Last post by swordmaster2k on July 26, 2015, 03:51:43 AM »


Has anyone else seen this creation from Meccano that is being launched next month? I've been researching the cheap humanoid market and this caught my eye. It has some potential for some serious social robotics projects. Although it lacks manipulators and is limited to flat smooth surfaces. Anyone any thoughts on this?
40
Electronics / Re: Problems with MT8870 DTMF Decoder
« Last post by asif5955 on July 25, 2015, 02:43:27 PM »
Hi i am new here   ;D
Although it was an year old post  but  i am replying to it
I have  made DTMF circuit using Mt-8870 and got solution to the problem you were stating
You Audio jack is not properly grounded
i was having same Problem but when i connected Audio jack's body and negative pin with -5v (power supply)
this problem was gone
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