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JonHylands
09-14-2007, 09:36 AM
One of the things we're experimenting with over at the Brain Engineering Lab is finding better ways to build custom parts. Most of the parts for BrainBot (http://www.bioloid.info/tiki/tiki-index.php?page=BrainEngineering+BrainBot) have been machined on a CNC milling machine (Sherline) - the chest compartment is a good example.
It is made from 1/4" and 1/8" Delrin plate, machined to fit, with a lot of machine screws to hold the whole thing together.

Its fairly labor-intensive, and not really a good use of my time, since we want to build a number of this particular model.

So, since Dartmouth College has a machine shop on-campus which has a Dimension 3D printer, we've been experimenting with printing some of the parts. The grippers were an obvious part, but the chest compartment is a real challenge.

I've finished the CAD model of the first revision of the "printed" chest, and its an interesting comparison to compare it with the machined chest. Once I get the actual printed chest in my hands, I'll post a picture of it here.

Anyways, here are the CAD models of the two techniques. First, the machined chest:

http://www.bioloid.info/Chest-Machined.png


This chest is comprised of ten different pieces, all of which are machined to shape on my CNC mill, with dozens of holes, some threaded, some not (which is very labor intensive).

Here's the printed chest:

http://www.bioloid.info/Chest-Printed.png

Two pieces, both printed (the darker piece is the circuit board support). All the holes are pre-drilled, and the ones requiring threads can just be threaded directly with a tap. For tapping plastic, I typically just put the tap in my cordless drill and use that, which makes it much faster for threading holes.

The nice thing with the printed chest (aside from the labor-saving) is it looks much better, and the support pieces and brackets can all be integrated into the piece as it is printed.

- Jon

Alex
09-14-2007, 06:09 PM
I always wondered what using those 3D printers (http://en.wikipedia.org/wiki/3d_printer) was like. How do you like using it so far?

I take it you feed the printer your CAD drawing and it goes to town?

Good luck on this project Jon! I bet it's going to be a challenging one:) Keep us posted!

JonHylands
09-14-2007, 10:03 PM
Yeah, using a 3D printer is a real kick. Wish I had one at home :-)

You basically build a solid shape in CAD, which can have fairly arbitrary shapes.

http://www.bioloid.info/NewGripper-01-small.jpg

That's the new gripper I did - all the white parts to the left of the servos are printed on a 3D printer from ABS. The fingers have indents for touch sensors, and hollow channels through the middle for the sensor wires to go.

Once you have the model done, you export it in STL format, and send it to the printer. It takes several minutes to several hours to print the shape, depending on how much material it needs to use, and how much support material it needs to print.

- Jon

Matt
09-15-2007, 07:12 PM
Hey Jon,

Your post made me think of Techshop (http://techshop.ws/). They had an area out at Makers Faire this summer and that's where I found out about them. It's a pretty cool idea, description from website:

"TechShop (http://techshop.ws/)is a fully-equipped open-access workshop and creative environment that lets you drop in any time and work on your own projects at your own pace. It is like a health club with tools and equipment instead of exercise equipment...or a Kinko's for geeks. TechShop was founded in 2006 by Jim Newton, a lifetime maker, veteran BattleBots builder and former MythBuster. "

JonHylands
09-15-2007, 08:36 PM
Yeah, if there was anything like that here, I'd definitely be a lifetime member...

Today I did the CAD model for a new camera mount, which looks like this:

http://www.bioloid.info/CameraMount.png

Its basically a mount for a pair of Swann Blackhawk (http://www.amazon.com/Swann-Sw-p-wbh-Black-Wireless-Camera/dp/B000B6LCI2) wireless cameras. We've decided to use these cameras on the walking version of BrainBot, since they weigh only 32 grams each, as opposed to the green wireless cameras on the first BrainBot, which weigh in at a hefty 230 grams each.

- Jon

Alex
09-17-2007, 10:16 AM
Great stuff Jon!

What kind of software do are you using for the stereoscopic vision?

JonHylands
09-17-2007, 01:58 PM
I'm not - the Brain Engineering guys have their own vision system they're working on.

- Jon

Matt
09-17-2007, 02:52 PM
We bought that same wireless camera to try to attach the the X-ufo so we could fly it remotely. After about 2 minutes of trying to control the X-ufo we gave up on any hope that we would ever be able to fly it by watching a monitor in another room. Our dreams were smashed :(

I liked the camera though! So small and light!

JonHylands
09-17-2007, 02:55 PM
Yeah, that's the main reason I picked the camera - its weight. Plus, it has its own built-in lithium-ion rechargeable battery, and each camera can be switched to any of the available four channels.

- Jon

Alex
09-18-2007, 04:12 PM
Hey Jon,

Is this the same company that does your Vision Software:

http://www.marketwire.com/mw/release.do?id=770867

JonHylands
09-18-2007, 08:17 PM
No, the Brain Engineering Lab is an R&D lab that is part of Dartmouth College in New Hampshire. They do AI research, and part of that is doing vision processing work.

- Jon

Alex
09-19-2007, 09:45 AM
gotcha, thanks:)

JonHylands
09-21-2007, 03:57 PM
Okay, so I got the printed chest in the mail today :-)

http://www.bioloid.info/PrintedChest-01-smaller.jpg

I'm really impressed with how it came out.

- Jon

Alex
09-21-2007, 03:58 PM
That looks incredible Jon, excellent job!!

JonHylands
09-21-2007, 06:51 PM
Here's a picture of it with the new (printed) head mounted, and the arms one (minus the grippers)...

http://www.bioloid.info/PrintedChest-03-small.jpg

The cover plate says "BrainBot" in raised letters, which is another cool thing you can do with 3D printers...

- Jon

JonHylands
09-27-2007, 03:01 PM
And here it is with the legs attached - I'm amazed at how much quicker it is to put this thing together, compared with the last one I did...

http://www.bioloid.info/BrainBot2-01-small.jpg

- Jon

Matt
09-27-2007, 11:52 PM
:eek: Oh my god he's lost an eye! Where is his eye! :eek:

Matt
09-27-2007, 11:55 PM
This robot project is unbelievably impressive Jon. You are building it practically from scratch. There is so much engineering on so many levels in this project. I'm highly impressed. I'm wondering, While deciding to make the over all size of the bot did you do calculations to see how the actuators would fair with the torque strain and all that?

JonHylands
09-28-2007, 07:54 AM
Thanks Matt. Interestingly, this robot is basically a direct, homemade competitor to the Speecys SPC-101C. It is controlled from a PC through wifi, has wireless video, and control is done through a simple socket connection on the PC.

I didn't do any calculations for torque - the first BrainBot ended up being too heavy, mainly because of the cameras I chose (230 grams each). However, with that body transplanted onto the tracked base, the head weight isn't as much as a factor.

This one uses much lighter Swann Blackhawk cameras (32 grams each), which even have their own batteries built-in. The printed chest is also much lighter than the machined chest (we estimated it would be about 1/2 the weight, which will save a further 160 grams or so). You can add a certain amount of weight to a Bioloid from stock, because the servos have so much more torque than most other humanoid kits out there.

The next humanoid is going to be RX-64 based, so torque isn't going to be nearly as much of an issue.

- Jon

Alex
09-28-2007, 10:27 AM
With the other camera missing, it almost looks like your robot is winking at me, haha!

Great stuff Jon! You're planning on using RX-64 servos next? Torque will no way be an issue with these; Those servos are monsters! I can't wait to see what you do with these beasts of a servo:D

JonHylands
09-28-2007, 03:31 PM
I'm really looking forward to working with the RX-64's. I'm going to end up designing a bunch of brackets like the AX-12 uses, and printing them with the 3D printer.

- Jon

Alex
09-28-2007, 03:36 PM
How strong is the plastic you use for the 3D printing? I would think that the RX-64's would rip that plastic apart:)

JonHylands
09-28-2007, 04:03 PM
Well, the plastic is ABS, so it is very strong. The key is to make sure you have enough material.

For example, looking at the finger on one of my new grippers:


http://www.bioloid.info/GripperFinger-Quarter.jpg

Its about 1/4" wide at its narrowest point, 1/2" high, and about 2.25" long. I am a big strong guy, and I can't break that in half with my bare hands, even though there is a hollow channel running down the middle of the finger.

For pieces where really high strength is warranted, I will machine them from Delrin or Aluminum, but I suspect for most of it the printed plastic will be enough...

- Jon

Alex
10-01-2007, 09:20 AM
Wow, I didn't realize that ABS was that strong!

What sort of plans do you have with this new robot Jon?

JonHylands
10-01-2007, 11:44 AM
Well, its mostly confidential, but one of my priorities is to make it walk using a dynamic gait, so that it can walk outside on my property. My back yard is very rough and irregular, with hills and rocks and trees and such.

- Jon

Alex
10-01-2007, 12:08 PM
Can't wait to see it all (including your latest) in action:D