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Macropede studies
05-31-2014, 01:51 AM
Post: #21
RE: Macropede studies
It's runing:
[Image: 2014-05-30.174122-k.jpg]


Now the servos are stronger than the gear teeth. I changed already two wheels. Alignment of the gear train is important. The servos has to be positioned very accurate - have to think about this.

Rainer
http://www.steamboating.de
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05-31-2014, 04:48 AM
Post: #22
Star RE: Macropede studies
You really made... Beautiful.

One point I found difference is the directions of crank.

Please see this picture.

[Image: IMGP4248cSAI2.JPG]


I couldn't find why this direction is better yet, but I feel it's stable to walk.
You can repair this, but you maybe need to loosen screws and adjust all cranks.
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05-31-2014, 06:11 AM (This post was last modified: 06-01-2014 03:06 AM by steamboat.)
Post: #23
RE: Macropede studies
My daughter Rebecca already told me that the movement of "your" legs are nicer than mine - now I know why - and yes, yours is much more stable and maybe even need less torque at one leg!

And yes, I have to loose 30 screws...

Thanks for this hint!

Rainer
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05-31-2014, 07:34 AM (This post was last modified: 06-02-2014 02:53 AM by steamboat.)
Post: #24
Result
I changed one side to see what will happen:

[Image: 2014-05-30.232158-k.jpg]


But still did it wrong! I tried to set the legs with 45° in difference. With this I have a maximum of 4 but mostly 3 touch points to the ground. You only have two - this gives the wave a more uniform look.

My arm don't allow me to reset it again tonight...

Rainer
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05-31-2014, 08:37 PM
Post: #25
It's running
Hello Sho,

I changed the timing of the gear but now I went to far. Have a look at this



Because I made only one gear-crank combination, the "wave" is to long now. I have to think about how to change this. The solution will be more gear-crank combinations which has to be combined in the right sequence.

Rainer
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06-01-2014, 01:08 AM (This post was last modified: 06-01-2014 01:11 AM by sho.)
Post: #26
Heart RE: Macropede studies
Guter Abend !

Please takecare your arm. It maybe tired to lose all screw...

I understand why it can't walk very much, because the wave is different.
2 waves = 45 degrees crank lag maybe the best. I think you already understood this.

But, is it difficult to make as 2 wave ?
I didn't understand very much why you made 3 waves one and 1 wave one. Smile
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06-01-2014, 04:31 AM
Post: #27
RE: Macropede studies
My crank gear has it's crank pin on top of one grove. With this my drive train alows only the two crank steps of 22.5° or 90-22.5 = 67,5°

With 16 legs and 22.5° per leg you make 22.5° * 16 = 360° at all legs - equal 1 wave

With 16 legs and 67.5° per leg you make 67.5° * 16 = 1080° at all legs
1080° / 360° per wave = 3 waves

So I have to redesign the crank gear...

Rainer
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06-01-2014, 07:17 AM
Post: #28
RE: Macropede studies
Here it is. I solved the problem with only one additional crank-gear:

[Image: 2014-05-31.220635-k.jpg]


Will change the other side tomorrow and make a video.

Rainer
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06-02-2014, 02:49 AM
Post: #29
RE: Macropede studies
It's running with 45° crank difference realized with two different crank-gears and servo motor.

I used Sho's Arduino code with a linear acceleration. This means that the motors start turning slow and becomes faster after a while automatically. In the middle of the film I also changed the max speed limit - you can notify it - if you know it. The acceleration is good to bring the torque smoothly into the gear. This will reduce starting current and stress to the gear teeth. Have never used such a code for a toy vehicle before - so it let me guess that Sho have had some issues about torque and starting current also - but of cause it gives it a good and smooth look.




Rainer
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06-02-2014, 04:59 AM
Post: #30
Shell for Macropede
I started to design the shell. For me as an engineer it is difficult to do things like that. This is a mixture of animals I know and the possibility to print it at home. The plan is to print thin flat shells which will be bend over a frame and bolted together. This flat shells can get some structure like rivets or animal armor while printed.

First quick version - just taped together
[Image: 2014-06-01.184453-k.jpg]


Second attempt with more stiff paper to simulate the plastic and with "bolts"
[Image: 2014-06-01.193913-k.jpg]


OK - I am at the beginning... I will not integrate the eyes but give it some kind of housing.

Next problem is to find something animal like to mount at the end and at the front - suggestions?

Rainer
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