Penguin New Servo Feet Video

Interact

Ok I gave up on finding my video camera and shot a short video with my PDA phone. It's not too bad for a phone vid. A little jumpy.
I haven't had time to work on the walk code for the new feet much this week, I still need to smooth out the transitions.
http://www.youtube.com/watch?v=5hA6oQE5Z9E

Here is a picture of where I put the port for the new servos.


By putting two jumpers in, the LED display becomes fully functional again.


The servo connectors are next to the tilt and stride servo conectors because there is not enough power on the computer board to power the servos.


Here is a picture of just the feet.


Post Edited (Interact) : 9/22/2007 5:22:57 PM GMT

Humanoido

Interact, really great job! Your cel takes very good vid too.
The photos are very good - I like the neatness of the motherboard
mod. Well done!

I think we have a new kind of robot with these feet
making Penguin a four servo robot. It looks much more easy
to turn in various directions and much quicker.

You now hold the record for the very first hardware
modification to Penguin! I also like the software results
in the demo movie.

Where do you buy the feet?

humanoido

slashsplat

Absolutely the coolest hardware mod.
Now you have me thinking of doing this to my humanoid MANOI...
Darn. Too many cool things, too little time.
How can I buy the parts?

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slashsplat
/* Ira Chandler */
BotConnect.com

quickster47

Like wow! Interact that is one great job on the hardware and software.

Still trying to figure out the pieces of the feet. Perhaps you could help with some more descriptions of what you used.

Carl

Interact

The feet are made of sheet aluminum and a large diameter sealed bearing. The little brass wheels I also made. Used a hack saw, file, drill, and a vise. The top piece would be a candidate for CNC. and the bottom piece probably stamped.
I will try to put up a drawing later today, once my store settles down.

Humanoido

You must have access to a machine shop to do all this!
How did you attach the servo? Tap tiny screw holes in
the metal for the horn?

humanoido

Interact

I do own a lathe, but it was not used for these feet. Really just a hack saw and pliers to bend the metal into shape. File the rough edges. Come on, it's not that good of a job, the pictures show all the rough edges. For the round base that is cupped, I cut the round piece out of sheet alum, put a socket on one side and found a bicycle part that had a large round hole and put that on the other side put the whole thing in a vise and pressed the circle into the cup shape. Needed to do this in little steps until the cup reached the servo. As far as attaching things Super-Glue is my friend. As long as you use the real deal that comes in the large 2oz bottles with accelerator, it is very strong and durable. I did screw the servo arm to the round cup-foot. The bearing is a headset bearing from a bicycle (I think you might guess what kind of store I own) but there are better and lighter bearings than the one I used. If this were to go to production the top piece would be machined and mount holes would be integrated into the design. The Parallax servos have a better mount position on them for this project, but I found these servos next door to my store at a second hand/thrift store, inside a broken r/c plane. This is the first and only robot I own and don't have a supply of parts etc. I stole the wires and connectors from my dead computer. I am actually working on another design for the foot, it was my preferred design from the beginning, but lack of parts led me to the design shown here. I was a computer engineer back in the day, Interact was my first job, if you do a lot of digging you will find that that was the second home computer to go to market. I then went on to work on the Landsat satellite project, and when they put a bed in my office so I wouldn’t have to go home .. I kind of quit. I then became a professional bicycle racer and traveled the world racing. I recently had back surgery and have been spending my riding time in front of a computer, and I stumbled across the parallax site, and this re-kindled my old interest. (way more than you wanted to know).

Here is a drawing (under statement) of the pieces.
The servo arm is connected to the cupped foot.
The cupped foot is·attached to the inside of the bearing.
The top piece is·attached to the outside of the bearing.
The servo body is·attached to the top piece.

Tiger

Interact - That thing is really cool for sure! Love it! Two questions... Looking at the pics and video, it isn't obvious to me why you need the little wheels. Seems like those giant bearing would take care of everything. Also, I'm wondering what drawing program you used in that last pic.

Super nice job and very creative work. Congrats! ...Tiger

Interact

The little wheel is ness because when one foot is forward and the other is back, the balance point is further back than the edge of the circle-foot. The original foot is more or less square and balance point is taken care of by that fact. If the wheel wasn't there the penguin wouldn't be able to pick up it's back foot. Stability isn't a problem once it gets onto one foot. I did have in mind having the little wheel on a hinge so that it only put downward pressure when the Penguin wasn't tilted. Not too hard to implement mechanically. I also could have solved it with an additional waist pivot that attaches to the tilt servo that is actually quite easy to implement. But … I have a better idea and am working on that now.

The "drawing program" is well .. I use quite a few in combination. this used Maya, and a hybrid render that I wrote part of. Texture's are from who knows where, when you do this stuff a lot you build up a huge texture library and I never remember where they originally come from. I do TV commercials that need CG, on the side.

quickster47

Well I'll be danged. Thanks much for sharing the drawing.

Last night I played around with using a thrust bearing for the round foot to pivot on. It might work out but I need access to my mill and lathe which is in Orlando. Right now I am working in Washington, D.C.

Carl

slashsplat

Interact said...
(way more than you wanted to know).

Inquiring minds WANT to know. One of the greatest things about this hobby is learning about the VERY interesting people. The variety of disciplines is astounding and the life experiences are fascinating. Your history adds another level of interest to this passion of ours, and makes it so much more human than just metal characters strutting around. (One day, ask humanoids about a few interesting things he has done in his storied history...)

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slashsplat
/* Ira Chandler */
BotConnect.com

Post Edited (slashsplat) : 9/26/2007 12:18:09 AM GMT

Interact

Ok, I didn't think anyone else would be interested in trying this. I think I am going to go a different direction on the design, but if I was to do this design again I would use a B-543 bearing instead of the one I used. (pictured) It is quite a bit lighter and not as tall. Also I removed the seals from the bearing to reduce drag, and the grease removed so as not to attract dust. Turns out the servos are a lot stronger than I thought, and probably would work without removing the seals. The part I had the hardest time with is trying to get the acceleration of the servos right to minimize slipping. Even a small step is still at full speed and toque, and that can cause the foot to spin a bit·on the ground if it's on·a slick surface. It would be better if you could control the speed of the motor and not just the size of step it will take. I think a re-design of the electronics inside the servo would be a great solution. I got it to work well·with software but it wasn't that simple, and the coding for the motor acceleration after optimization is .. well… I’d hate to have to add comments to that piece of code. Not that its big, just a lot of SHIFT’s and AND’s and X-OR’s. Kind of hard to wrap your head around unless you were the one writing it. Anyway if any one want’s to try this, and it seems there are, I’d love to help if I can, I’m just stuck in front of this screen most of the day anyway.

Humanoido

Interact, the info is greatly appreciated, especially
the part about your life stories. Now we know where
all of this incredible talent came from!

I remember the Interact microcomputer from 1979.
Like most new micros of that day, it had the cassette
tape standard built in, ran off an 8080 chip with base
8K and 2k ROM. It's reported that several thousand
machines were manufactured. BASIC was loaded in
from tape, and it ran off a TV - the video modular was
built inside. It had a very attractive all-in-one design
molded with the full ascii keyboard. It sold for
around $300. It was one of the great microcomputers
that significantly contributed to the overall evolution
of the computer as we know it today.

These computers are now in museums. If you own
an Interact computer, it's worth more than a hens'
golden egg.

humanoido