Building humanoid similar to Asimo and Qrio

[limor]

Here's a first take on the shoe.
I ended giving up on that parallelogram approach as it would complicate things when all I need here is a bit of suspension in the heel.
The front of the foot will end up much wider
Also I am going to try and add a torsion spring at the front of the foot to ease walking. Humans use the toes to at the end of the stride to push and balance. Our guy will have torsion springs which will make a fun task to program his walking.

[limor]

Managed to get a first sketch of the torsion spring for the front of the foot (to allow him to perform a more human-like stride, unlike Asimo & Co. who always have to step with a full foot on the ground because their foot can't be bent)

I took the torsion spring from clothes hanging peg. I have no clue what are the physical parameters of the peg's spring and i don't know yet what will be the required parameters for helping the robot during fast walking, but if it should be ok as an inexpensive place-holder.




There's a 3mm hole where I plan to put a screw or rod in order to hold the two pieces of the foot together not relying only on the spring (as do the pegs do which makes the peg stable only in the alligator bite mode)

just realized that after all the calculations, I have reversed the ends of the spring..

[limor]

Here's the foot with suspension and torsion spring toes..

[nicolas gomez]

Here's the foot with suspension and torsion spring toes..

Hi limor!
here a couple of pictures that can help in your design













regards

[siempre.aprendiendo]

wow, looks very good

I think that I'm not the only one waiting anxiously to watch a video showing a walk with these feet

[limor]

Hi Nicolas
Thanks for the post. Again we see that no idea is original

These look very professionally done!

I'm curious about the texture of the plastic feet. They offer the parts in different colors. It looks like 3D printed but with some additional coating?

RoadNarrow SkewlZone Humanoid Brainpack Foot 2.0

[limor]

I finally reworked the knee and now i'm quite happy with it.
It is fixed onto the AX12 "wig" with several screws from 3 different directions.
Each of the 2 sides of the knee is fixed onto the axis at 3 points (2 from the special knee bracket and one from the fishing wire linking the pulleys)
The axis itself will be made out of fiberglass rod (kite rod).
The knee bracket is designed to be 3D printable without messy supports.





I too can't wait to have all the parts, build the robot and make him walk.
There's still lots of work designing the hands and head and most importantly the outer shell. Our new CNC is taking more effort that we had expected. At the moment we we are having trouble cutting aluminum because the drill bit melts the material making impressive metalic splashing effects. Waiting for new drill bits and air pump to cut the aluminum in order to build the central body of the robot.

[PaulL]

... At the moment we we are having trouble cutting aluminum because the drill bit melts the material making impressive metalic splashing effects. ...

Melts!?! I've never seen a drill bit melt aluminum while drilling holes! How many RPM is your spindle? I've been using 1/8 inch 4 flute HSS and cobalt end mills at around 4k RPM for milling, and regular cobalt or TIN coated HSS drill bits for holes.

[PaulL]

... Also wondering, what cutting depth and feed rate (inches or mm per min / sec)? You'll want to check out the feed rate recommendations for the tool to see how many inches / mm per tooth, RPM, etc. There are some free feedrate calculators on the 'net.

[limor]

... Also wondering, what cutting depth and feed rate (inches or mm per min / sec)? You'll want to check out the feed rate recommendations for the tool to see how many inches / mm per tooth, RPM, etc. There are some free feedrate calculators on the 'net.

Not sure about drill bit parameters. The spindle is Kress FME 1050 (20000rpm). we've destroyed quite a few of them the past week on the CNC. It is a learning experience. We've finally managed to get good results cutting HDPE plastic sheet (the robot bearings will be made of this stuff). reading on cnczone forum, it seems that getting good results cutting aluminum is more an art than a science. i'm sure we'll manage.

[nicolas gomez]

Hi Nicolas
Thanks for the post. Again we see that no idea is original

These look very professionally done!

I'm curious about the texture of the plastic feet. They offer the parts in different colors. It looks like 3D printed but with some additional coating?

RoadNarrow SkewlZone Humanoid Brainpack Foot 2.0

Hi limor!

the plastic used is this
ABSplus
Chemical Family: Synthetic Thermoplastic Polymer

perhaps these have not additional coating, may be is the print resolution do this effect in the finished piece


in this links a pdfs files with a complete full description
http://www.roadnarrows.com/store/aitdownloadablefiles/download/aitfile/aitfile_id/103/

http://www.roadnarrows.com/store/aitdownloadablefiles/download/aitfile/aitfile_id/104/


here a two videos of this skewlzone-foot-2-0

phpBB [media]

http://www.engr.uga.edu/~mvteachr/RobotVids/HumanoidHeelToe.wmv



And here other approach using servos

phpBB [media]

it use choreonoid to motion generation, its available in english Windows7, Vista, XP 32bit ,Ubuntu Linux

http://choreonoid.org/en/





http://tsumeguruma.blog46.fc2.com/blog-category-3.html

[PaulL]

Not sure about drill bit parameters. The spindle is Kress FME 1050 (20000rpm). we've destroyed quite a few of them the past week on the CNC. It is a learning experience. We've finally managed to get good results cutting HDPE plastic sheet (the robot bearings will be made of this stuff). reading on cnczone forum, it seems that getting good results cutting aluminum is more an art than a science. i'm sure we'll manage.

20k RPM is pretty fast - can you turn down the speed? Try something like 4k RPM, 7 IPM (inches per minute) feed rate, .010 inch (about .25 mm) depth of cut on a 1/8 inch diameter tool. Slow, but it's a good starting point for 6061-T6.

You say "drill bits" - I want to be clear about this - to me, a drill bit is for holes only. An "end mill" is for sideways and plunge cutting. You mean end mill, right?

Once you know the "Inches Per Tooth" (something like .002 inch for some 1/8 inch diameter end mills I have), multiply this by the number of flutes (typically 2 or 4), then by the RPM, and you have your IPM for the specific tool. Deeper depth of cut lowers the IPT and ultimately IPM.

Plastics cut much faster and are pretty straightforward - increase IPM until melting stops, use a really sharp tool.

Btw, what's the minimum resolution of your mill? It needs to be less than the IPT for any tool you will run. Otherwise, you advance and put way too much material into the tool.

Info:
http://its.foxvalleytech.com/MachShop3/SpeedCalc/feedratecalc.htm

There are also recommended rates of cut for various materials, I'll see if I can dig up a link.

[limor]

Hi Nicolas

thank you for the videos and link to choreonoid.org . looks like a very useful piece of software. shame there's no documentation or videos.

Also, the images you referenced can not be seen . please use this link to upload images to our server if you need.
http://robosavvy.com/site/index.php?opt ... Itemid=132

thanks!
Limor

[nicolas gomez]

Hi Nicolas

thank you for the videos and link to choreonoid.org . looks like a very useful piece of software. shame there's no documentation or videos.

Also, the images you referenced can not be seen . please use this link to upload images to our server if you need.
http://robosavvy.com/site/index.php?opt ... Itemid=132

thanks!
Limor

Hi limor now fixed the problem with the images

here a hello word sample in choreonoid and video tutorial

http://choreonoid.org/en/plugin-development/hello-world-sample.html

phpBB [media]

phpBB [media]

http://www.jsk.t.u-tokyo.ac.jp/rsj2011/_downloads/2Q1-2slides.pdf

http://www.jsk.t.u-tokyo.ac.jp/rsj2011/_downloads/2Q1-2.pdf


EXMAPLE TO EDIT SOME BEHAVIOR

http://translate.googleusercontent.com/translate_c?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=ja&tl=en&u=http://choreonoid.org/ja/startup-guide/editSampleMotion.html&usg=ALkJrhgEM9ouRH66ybOSe9LLp6KSUFpOhw#id14

[MarcoP]

Not sure about drill bit parameters. The spindle is Kress FME 1050 (20000rpm). we've destroyed quite a few of them the past week on the CNC. It is a learning experience. We've finally managed to get good results cutting HDPE plastic sheet (the robot bearings will be made of this stuff). reading on cnczone forum, it seems that getting good results cutting aluminum is more an art than a science. i'm sure we'll manage.

20k RPM is pretty fast - can you turn down the speed? Try something like 4k RPM, 7 IPM (inches per minute) feed rate, .010 inch (about .25 mm) depth of cut on a 1/8 inch diameter tool. Slow, but it's a good starting point for 6061-T6.

You say "drill bits" - I want to be clear about this - to me, a drill bit is for holes only. An "end mill" is for sideways and plunge cutting. You mean end mill, right?

Once you know the "Inches Per Tooth" (something like .002 inch for some 1/8 inch diameter end mills I have), multiply this by the number of flutes (typically 2 or 4), then by the RPM, and you have your IPM for the specific tool. Deeper depth of cut lowers the IPT and ultimately IPM.

Plastics cut much faster and are pretty straightforward - increase IPM until melting stops, use a really sharp tool.

Btw, what's the minimum resolution of your mill? It needs to be less than the IPT for any tool you will run. Otherwise, you advance and put way too much material into the tool.

Info:
http://its.foxvalleytech.com/MachShop3/SpeedCalc/feedratecalc.htm

There are also recommended rates of cut for various materials, I'll see if I can dig up a link.

Hi

Since i have been the one mainly using the cnc i thought i should answer this.

The Kress max rpm is 20k. However it was not run at this speed.

The feed rates i have been using are based on what the cam software recommends for aluminium : 15K RPM and 17mm/sec (40 inches/minute).
However the machine vibrates too much if i use these speeds so i have lowered them to 40/30% of those values. From my understanding you should keep the ratio between feed rate and RPM constant.

I don't have the parameters for the IPM right now, but i think they were ok, because i was getting nicely sized chips. About 2 to 3 mm length and a few tenths of a millimetre thick.

From what you are saying, i interpret that you are worried about too high of an rpm and to low of a feed rate, causing the flutes to rub the aluminium rather that digging into it.

Given the size of the chips, i believe the problem is mainly caused by aluminium building up in the flutes (i had to put one in lye to dissolve the aluminium). I have used WD40 to lubricate the bit and the aluminium, but after just a few seconds of cutting, the aluminium builds up, causing the bit to loose it's cutting ability. It them just rubs against the material, melting it and pushing it out of the way.

I believe the problem is mainly cause by the end mills i am using :

http://www.ebay.com/itm/160828340580?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

They are probably not sharp enough and the flutes are too shallow. I got a bunch of these cheaper ones, because i was already expecting to break quite a few of them.
We are also planning to add a mist system, since that seems recommended by most CNC user, to blow the chips away to prevent re cutting of chips, and to continuously lubricate the tool.

Have some better end mills on the way.

What would you recommend from this? We have collets for 8,6,4 and 3.175 (1/8inch).

Regards