-Knewt-

Knewt Video from 2006 Robot Rally

2006-11-07T11:00:00.002-05:00

Richard Bodor has posted some videos of the Robot Rally that include Knewt's presentation.
See the other competitors at this wonderful competition on the AHRC site.

All Knewt Videos:
Robot Rally 2006
Turning Sequence with head
A short walk
Turning 'sans head'
Squat Thrusts
Tap Dancing 1
Tap Dancing 2
Test Stand Movie
Servo Control Test

2006 vacum contest

2006-10-02T12:20:00.002-05:00

Bob Baxter and Keith Rowell's Vac-mobile in the 2006 rice contest.

Knewt at Beep Beep Gallery

2006-09-17T16:14:00.000-05:00

Knewt makes an appearance at the opening of Beep Beep gallery in Midtown.

I went to the Beep Beep gallery opening and displayed some robots and cards to promote our club. It's a small space with a cool sign off Ponce between downtown and Virginia Highlands. There were easily 100 people there. There was food and drinks and music. It was quite a party. There were about 10 to 15 artists represented. Knewt and "entourage" sat on a table with a stack of AHRC cards. The party was still going on at 11:30 when I packed them up.

keith, thanks for the forward and the cool email. people really liked your robots alot. i'm glad you had a good time.

Mark Basehore

Knewt wins First Place

2006-05-19T14:39:00.002-05:00

Knewt and his trophy sit on the Dekalb Tech 6 axis CNC milling machine

Knewt wins First Place in the Open Competition
of the 2006 AHRC Robot Rally

First and formost I'ld like to recognise Knewt's team members, Stuart Rolf and Bob Baxter for the fine work that made Knewt possible. We ran 3 motion routines on the parallax board that proved that the robot could move about and stand on one foot without falling down. The "not falling down" I think was the "clincher".

The Rally overall was a lot of fun, there was a fine array of robots present and I'm proud for Knewt to be recognized by such a prestegious group. Thank you AHRC for such a fine event.

Bob Baxter, Stuart Rolf, Keith Rowell

2006-05-19T12:44:00.000-05:00

Frank Borowick presents me with the first place trophy as Richard Bodor looks on.

COOOL! Well done, Sir. Were you way ahead of the also-rans?
Bill Hotch

There were 4 others, 1 lego with a hand (end affector), one with a camera, a butler, and a line follower. Knewt was less than 1 point above 2nd place. These are some very clever guys.

http://www.botlanta.org/rally2006/scores.html

http://www.botlanta.org/rally2006/index.html

2006-05-19T12:43:00.000-05:00

Knewt on the floor of the Open Competition Arena

Thanks to Dale and Ann Hetherington for the fine photos.

2006-05-17T12:01:00.000-05:00

commenting on the movements

Creative Loafing covers the Dorkbot meeting

2006-01-21T10:04:00.000-05:00

creative loafing article

Putting the "bot" in dorkbot that evening was presenter Keith Rowell. Rowell screened video clips of robots, including robots walking, robots running, robots fighting one another, robots shooting flames, a stylish robo-rhino, and much to the amusement of the audience, a robot kicking a wastebasket down a set of steps. When finished, he fired up his own creation, a biped robot named Knewt. It looked like a robo-dinosaur.
Andisheh Nouraee

Knewt Presents at the first Dorkbot Atl meeting

2006-01-15T11:14:00.000-05:00

Dorkbot presentation

Dorkbot is an art group that is making use of technology as a medium. Their motto is "people doing strange things with electricity". There were about 30 people there and they seemed to have a good time.

Knewt was 3rd on the agenda following Greg Kellum and Craig Dongoski.

Greg's endeavor uses a computer and midi dimmers to control lights. He did a very cool "layering" of control to add hand motions from a data glove, on top of a programmed sequence. It had an eerie "ethereal" effect, like dappled shade of trees in the breeze, or sun through broken clouds. He explained all the technical aspect pretty thoroughly.

Craig showed a system for reaching the "sound of drawing". He controls various electronic input with the user's input on a special piezo board that makes the drawing process "audible". The samples we listened to were very thought provoking. In the "nonsense" one could make out the scratching of a pen, breathing, barking, voices. The objective it seems is to evoke images from the listeners sub-consciousness. I'ld say it works, because you can't really discern the noises, but they are strangely familiar. Like a tool for getting into the creative "zone".

These are two fine examples of interface technology being used for creative purposes. Art being the motive. I wonder what it would look like to have art techniques being used for technological purposes? A cliche might be conductive paint used as circuitry. Any other suggestions?

In Knewt's portion of the show, I showed lots of the reference material that inspired Knewt to be built in the first place, and talked about what makes up the "robot aesthetic" in general comparing the "cute" factor in Japanese design to the "terminator" factor in American movie robots. The response was very good, I think it was a success.

Thanks to Jason Freeman for organizing the meeting and for having Knewt on the agenda.

Motion with Head

2005-12-29T11:19:00.000-05:00

a short motion sequence with head on

I'm not happy with the way Knewt "leans" when shifting weight. This is one of the issues I set out to solve when Knewt was started. The change in 2.0 to add more weight shifting ability, has re-introduced this leaning. It's not so bad really, but I would prefer that the head was kept perfectly level. I'm going to have to look into this more closely.

Two Heads Are Better Than One

2005-12-13T08:29:00.000-05:00

two heads are better than one

This photo shows the finished metallic head next to the un-finished white head. It was a couple of days work to get the head to the metallic state. I'll outline the steps here.

The STL process leaves a groved surface in random patterns as a result of the building process. I consulted Scott Washington who won awards at the IPMS/USA 2005 nationals modelling competition. Scott reccomended filling the gaps with Squadron white putty mixed 1:1 with Testors liquid glue. This is a pretty toxic smelling brew so be warned. The glue thins the putty to make it more spreadable. The pitfalls to avoid in using this on an STL model is to make sure you cover all the gaps. Since the entire surface is textured, it's easy to miss a spot. I put the putty on with a brush wich leaves brush strokes, creating a texture of it's own. I will try using a popsicle type mixing stick to apply the putty in the future to see if that works any better.

This putty dries pretty quickly. I began sanding after about 3 hours using successively finer grits of paper. 150, 220, 320, 600. This is the step when you find the spots you've missed. Stop here and fix these spots, then re-sand. The paint won't fill the gaps.

I sprayed the metallic paint on avoiding drips and runs. The next day when that was dry, I gave it a coat of Future Floor Polish. This makes the metallic finish have a slightly lighter color and smooth's the surface like glass, increasing reflectivity.

Notice the logos on the sides. These are custom decals made with Testors custom decal kit. The kit contains special paper, a spray fixative, and software. I wasn't able to get the software to even load, so I used photoshop to compose and print. The decal material is transparent. This fact slipped my mind and I was suprised to see that white areas on the logos were now silver when I applied them. This makes a cool effect though on the large red background area of the IronCAD logo, as the red is translucent and the silver highlight shows through. Another thing to be aware of is that the decal material is flexible. This is a big advantage to covering curved surfaces without wrinkles. But beware of sliding the decal around as the water dries. I pulled on a corner and stretched the decal material, slightly distorting the image. Be sure the decal is where you want it before drying away the water with a towel.

After the decals were dry I added another coat of Future floor polish.

I'm dissatisfied with the silver paint and am looking for a high quality replacement.

Knewt Beheaded

2005-12-09T21:27:00.000-05:00

STL parts

I got the STL parts for Knewt's head this week. As luck would have it, two of them on the same day. Stuart Rolf prepared the STL file and Ken Apple ran the job in Dekalb Tech's CAD lab. Barry Smith of DrafTech provided a head and a great poster that's in the next photo. Thanks a million everybody. (this is a perfect opportunity to use the colloquial "y'all", and even "all y'all" in this particular case").

Barry Smith gave a bottle of "Ambroid Pro Weld" to repair and strengthen the parts. These particular ABS plastic STL models are held togeather by a slight fusing of a .013 bead of melted plastic. These small threads can be torn away from the part if you try, or if it takes a bad fall. Considering how much Knewt falls, that's bad. But by saturating the part with the plastic welder, the fibers are much more strongly fused togeather and become almost as strong as a single piece extrusion. I coated both heads with it inside and out and didn't even use 1/4oz. It's like water and doesn't smell "too" bad.

After brushing the part with this stuff, it becomes shiny. A new advisor to the project, Scott Washington, recommended a filler paste and sanding to cover the texture left by the machine. I tried this and it worked quite well. Lots of had sanding is required. The grits I used were, 150, 220, 320, 600. The errors I made were to leave small gaps in the sanding putty. These were most evident on the vent slots on the top of the head. So I sanded and painted it again. I think by the third time I paint this head, I'll be up to amature status.

2005-12-09T21:26:00.001-05:00

head on

It was wierd seeing the head on for the first time. All the screw holes and bosses worked just fine. It's held togeather with #6 selft tapping screws from Austin Electronics. All the holes lined up ok. I had to cut an inconspicuos part off one piece to allow it to fit. There are several improvements I would make on the next pass. The're are ribs in the lower part that didn't print in both cases. But the intresting thing is that they weren't the same ribs in both cases. I reinforced those areas with plastic plates after ward.

Removing the part from it's building plate and extracting it from it's scaffold material is a pretty big deal. I've heard that the DrafTech office has a water soluable scaffold material and you throw it in a bath to seperate the two. Stuart said that part of his head broke just on scraping it off the plate, and again more cracks from trying to remove all the scaffold material. There was still a little of this light gray scaffold material left when I got it home and It was indeed difficult to remove, especially in small crevices and inside screw holes.

2005-12-09T21:26:00.000-05:00

Knewt beheaded

The eye holes are sized to 3mm LED's and I have mini O-rings on the protruding green lites. I inted to leave this head translucent. I like the fact that light passes through it and will try to incorporate a mouth "indication" behind the face without cutting pass throughs. You can see the base of the silver head in the forground.

2005-12-09T21:15:00.000-05:00

silver head

Here you can see (or almost see, anyone want to buy a camera?) logo's added to the white head and circuit boards mounted inside the silver head. We've decided to build the second body up as version 2.0 also and work on motion routines in tandem.

I chose silver for the painted head to emulate the finnish on the aluminum. White and black and clear are the most common plastic colors on the body. There is a rainbow of colored plastic wires, other wise the silver on the aluminum is the most prevelant color. What color would you choose for the head?

Does anyone have a suggestion for how I might tint the white head from the inside surface. It would need to be a translucent dye or the like. Perhaps a blue dye added to the plastic welder solution would do the job. I bet art markers would do it. Does anyone have suggestions for a pattern on the head?

Actually this is a perfect time for a critique. I'll get some better photos up soon.

Knewt at Draftech

2005-12-07T11:46:00.000-05:00

Knewt at Draftech

I had a good time Friday talking about robotics and CAD. There were about 20 - 25 people who came over to my table and had a good look at Knewt. 90% of those had some comments to make like "very cool" or "pretty neat". About half inspected the mechanism closely and offered a question about it's design. It seemed to break the ice for even the most quiet attendees. I met some old workmates from Nordson coincidentally. We reminisced.

The Lithium batteries died halfway through, but I was able to hook the power supply back up pretty quickly to finish. I really like the poster alot. I'll take it along on my next presentation and show off Draftech along with Knewt. I wish I had gotten a photo when people were milling around but I was busy dealing with the bot. Scott Walker, you would have been the perfect candidate for that task. What was I thinking?

The event was the 4th annual SolidWorld user conference held by DrafTech Systems Inc. in Lawrenceville. The white cabinet to the right of the table is the Dimension STL printer that produced one of Knewt's heads. The printer lays down a .013" bead of ABS plastic, building the prototype part layer by layer. Thanks a million to Barry Smith for the invitaion and the wonderful posters and especially the STL parts.

Barry Smith
President
DRAFTECH Systems 1730 Spectrum Drive Lawrenceville GA 30043
USAPhone: +1-770-963-8856 Fax: +1-770-963-7056
http://www.draftech.com/

Testing Servo Ramping

2005-12-05T13:48:00.000-05:00

testing ramping on ServoMojo

After having used the Parallax controller for a while I'm beginning to miss the gentle ramping provided by the BDmicro ServoMojo. Bob wired the "position pot" on a standard servo to the scope, so that we could view the position feedback directly.

2005-12-05T13:46:00.000-05:00

without ramping

This screen shot shows a normal servo command that is a straight line from starting to ending point. This translates into a servo motion that goes from full stop to full speed at the beginning of the motion, and vise versa at the end of the motion. The "speed" that the servo moves is choosable with the Parallax board (rate), but the transition from stop to moving is still one step. The abrupt changes in speed cause rocking and jerky motion for a bot like Knewt. It's an issue we considered trying to solve with MCU management of the "rate" variable every 20ms. But why do that when it's built into the ServoMojo?

2005-12-05T13:44:00.000-05:00

with ramping

In this screen shot, you can see the curves at the ends of the motion. The servo transitions from stop to full speed in a gradual fashion and slows to a stop in the same manner. This is shown by the gentle "S" curve shape on Bob's scope. Some of the original videos of Knewt showed this fluid motion. We're driving the servo from the ServoMojo using a ramp setting of 15.

Knewt 2.0 is walking

2005-11-09T22:04:00.000-05:00

Knewt is walking again, and I've converted the movie format to Windows Media Video. The ASF format of previous movies was obscure, this one should be availble to more users.

This is what happens when you reach the end of your teather. We're working hard on removing the teathers entirely. The batteries and controller are the culprits.

See the movie here.

Vacuum Molded parts

2005-11-06T20:42:00.000-05:00

Joe Fishback's Robot and Knewt 1.0 & 2.0

Joe Fishback is a vacuum molding expert that I met through the Metal Munchers ( a machinist's club). We met last week and talked about making Knewt's head parts using this technique. You can see the parts Joe molded for his robot in the photo to get some idea of the thickness of the material and the look of such parts. I'll be re-designing the head parts to better accomodate this molding process should there be an opportunity to make these in any numbers. I'm still persuing using STL for the prototype head parts.

The Twins Are Up

2005-08-30T21:30:00.000-05:00

the twins
Keith Rowell Design

Twins yes, however not identical. 2.0 is stronger heavier and not yet completely assembled. (that's 2.0 on the right) I managed to get a test fit of all the physical parts togeather this week, as well as solder the foot sensor boards togeather and route the wiring. I've used different linkages on 2.0 as well. Only time will tell if they're an improvement.

2005-08-30T21:19:00.002-05:00

front quarter
Keith Rowell Design

There's a good bit more bulk on this one, making 1.0 look "svelt" by comparison. The foot sensors and the belly motor are the giveaway.

2005-08-30T21:19:00.001-05:00

profile
Keith Rowell Design

The sensors use two 4 wire ribbon cables. With that and the seven servo motors, the body cavity is filled with connectors.

2005-08-30T21:19:00.000-05:00

rear quarter
Keith Rowell Design

The 1050mah battery "back pack" was planned long ago. We have newer lighter 650mah LiPoly cells also to try out. They will fit in the head. The option remains to use either. If you look closely you can see that the upper leg parts on the right leg are transparent. Those are poly carbonate while the left leg is aluminum. Which would you prefer?

Knewt 2.0 under construction

2005-08-25T22:27:00.000-05:00

2.0 being assembled
Keith Rowell Design

Parts are comming in every day now. This photo shows the new acrylic body parts from Pololu. These were re-configured to hold larger motors and have gone togeather without a hitch. These are 1/4" and 3/8" parts, (thicker than their usual 1/8") They went the extra step and ran thecutting pass twice to "polish" the edges. They're water clear, and look like crystal. It's almost a shame to drill and tap any holes. Tomorrow the new ball joints and plastic gears arrive. This thing will be togeather in another week.

Testing the Parallax Servo Controller

2005-08-24T23:23:00.000-05:00

viewing signals
Keith Rowell Design

Our previous controller "The ServoMojo" so kindly donated by BDmicro is nice in that it has super smooth "ramping" that slows the motion at the beginning and end and ramps to a higher speed in between, for any particular movement of a servo. Being a beta tester, it's GUI poser program was an "alpha" Linux code program that we never got to work. Writing motions was a slow and tedious task, smooth though they were.

We decided to test out the Parallax Servo Controller because it has a slick GUI poser, is USB, and fairly cheap. There's caveats here as well though. The Parallax program PSCI is vague on many issues and it was necessary to view the signals to decipher what was actually going on.

2005-08-24T23:21:00.000-05:00

ascii and PWM
Keith Rowell Design

One line is the ascii command read from the serial data line. The other is the PWM sent on the servo's signal line. Using this method we verified that the files we made with PSCI were what we intended. (they aren't viewable as text, nor are they hand modifiable with a text editor because they're encryped.) Bob has modified his ServoMojo code to transmit ascii instead of hex. And we can use this to send commands to the Parallax board. The PSCI GUI becomes merely a poser to test settings on, then we make text files for the pic to replay those positions.

2005-08-24T23:20:00.000-05:00

PSCI screen shot
Keith Rowell Design

The very basic idea is to move the bot into position with the sliders, save, and repeat.

You don't get what you might expect each time however, and the documentation doesn't answer very many questions.

After some investigation we learned, for instance, that the "goto" command works "befrore the current frame" so it's best to use it in a subsequent frame with nothing in it. Nice to know if you spent a while posing the thing.

There's a feature that will copy the contents of the current frame to the next frame. This happens automatically, "under certain conditions". I've not yet deciphered what those conditions are! So frequently I go on to the next frame and all the motors reset to 1500 (neutral). When this feature works, you can change the value of one motor, and you get a simple change from one state to another. When it doesn't work, you have to reset all the motors manually from the values in the previous frame. Writing them down in a notebook is handy when doing this. You see my point.

Choosing a delay value is the next issue. The delay is recognized in any frame, if any motor that changed values in that frame has a delay value. The delay will allow motions in that frame to complete without truncating the motion before the next frame starts. There is no way to determine before hand if your motion will finnish however except to try it. Parallax couldn't answer the question, "how do you calculate the delay value based on the speed setting, and distance travelled? So it's still a long trial and error process to make motions. But it does move faster than our previous hand coding of text files, somewhat.

In the future we'll work on a more dynamic motion solver that takes input from gyros and accelerometers.

Proximity Sensors

2005-08-24T22:39:00.000-05:00

4 prox dots proximity sensors being populated
Keith Rowell Design

I chose ProxDots for proximity detection for their size and weight. Here Bob Baxter is soldering the surface mount resistors and diodes and such. You can just about make out the 4 small circuit boards through the magnifying glass. These small sensors have a range of only about 4 - 6 inches. That's plenty for the Seattle "Walking Race".

2005-08-24T22:38:00.000-05:00

robot surgery

You solder one end down then the other, a drop of solder on the part or the iron or both is enough.

2005-08-24T22:37:00.000-05:00

did I mention that this stuff is small?

This is a weak camera but you get the idea. All the parts were that small.

2005-08-24T22:36:00.000-05:00

quite small

Dont sneeze!

2005-08-24T22:35:00.000-05:00

I think this one went in my shoe laces

We spent a few episodes crawling around on the floor looking for something the size of "a chip of rice, a bread crumb, no that's a nick in the floor, I can't pick it up, ok now I got it, where'd it go?"

2005-08-24T22:34:00.000-05:00

viola!

The LED light means success !
All 4 sensors assembled. That was fun!

Testing Turns

2005-07-12T09:41:00.000-05:00

Take a Right at the Light
Keith Rowell Design

I'm having trouble uploading videos to my storage site right now. If anyone would like to volunteer a spot I'll use it. This video shows Knewt walking in a circle.

Knewt turning movie.

OK I've tried using the Internet Archive site and the movie is now available; click here. This site is free, but it did take 2 days before it was available online. Also, it has been re-sampled or converted somehow and the resolution is lower. Thanks to Michael Sprague of Holland, Michigan for the suggestion.

Knewt Bulks Up

2005-06-20T23:30:00.000-05:00

Knewt Bulks Up
Keith Rowell Design

After a long absence from the project, I am once again back in the saddle, and all the happier for it. We are adjusting the design to overcome some bugs revealed during testing and experimenting with a new driver ( more on the driver later).

Mostly this means larger motors. The balance motor (1 below) has had to replaced repeatedly, and the leg motors (2,3) show high stress under load but have not yet failed outright. These 3 were HS55's with a torque of 15in/oz's. They've all been replaced with 81's which have 49in/oz's of torque.

It appears that with the bulkier body, the head might could stand some scaling up. The image above shows Knewt 2.0 with modifications to the backplate and chest plate to accommodate these larger servo motors. There's also a new motor added for "active" balance at the ankles. I had hoped that "passive" linkage would do this sufficiently, but alas, the "play" in so many joints causes Knewt to "lean" toward the foot that's off the ground, ruining the "level body" appearance I wanted, not to mention making it that much harder to balance during walking. The "active" balance motor (4) will replace the passive balance linkage, and work in unison with the weight shifting motor (1).

2005-06-20T23:25:00.000-05:00

larger servo motors
Keith Rowell Design

The width of the 81 motors are the same as the 55's, but the length and depth are larger by 20% to 50%. The weight shifter (1) now protrudes further through the breast plate, and the leg motors (2,3) had to be shifted down and out under the leg retainer bar.

The width of the stance was left in it's original position, but the body mass is now thicker and longer.

By the way, I've pictured Knewt with an old camera body for a head, but can't find any trashed cameras. A defunkt micro cassette video camera or digital camera body would be perfect because of the brushed metal cases they tend to have. If anyone knows where to get trashed camera bodies, please let me know.

2005-06-20T23:18:00.000-05:00

rear view
Keith Rowell Design

In this rear view, the new leg motor brackets can be seen. They move the motors lower (further from the center point of the pivot) to give more leverage. There was plenty of travel here, so the travel lost by moving will not be missed. I'm confident that the tripled power combined with the extra leverage will overcome the hesitancy the 55's exhibited in the legs. The weight shifter however is in such a high torque position, (close to the pivot point) and needs so much travel, I'm keeping my fingers crossed that it wont have to be upgraded yet again.

Also visible in yellow is the lithium battery back pack. The origianl space inside the chest cavity is still available for the hydride prism cells, but the current plan is to use that space as a wire way and take advantge of the higher power density privided by lithium.

The active balance motor (4) had to be mounted underneath. I originally placed it vertically in the space between the leg motors (2,3). I liked the symetrical, vertical positon, but the space between the leg motors (2,3) is used during weight shifting as those motors rotate about the bearing center point shown in "red". With the current configuration, a weight shift rotation of 20deg is possible. The old design was only 14deg.

dont forget to check out the AHRC Mascot

2005-03-15T00:48:00.000-05:00

Tap Dancing

2005-03-07T01:35:00.000-05:00

tap dancing
Keith Rowell Design

http://www.mindspring.com/~rowell/MOL006.ASF

http://www.mindspring.com/~rowell/MOL007.ASF

Knewt does a little Gene Kelly impression tonight, showing off his fancy foot work (again, pun intended). I'm slowly getting the hang of using Bob's coding scheme for making motions with Knewt. This sequence shows that standing on one foot is no problem, indicating that walking will be well within the range of the "possible". I was suprised at how stable he is with foot fully exteded and waving about in the air.

The batteries are installed to demonstrate how they will affect the balance and power of the motors to carry the weight. We're going to talk more this week about motion schemes and the the possibility of producing a kit.

We expect to be able to offer a kit for somewhere in the $600 to $1000 range. Please indicate your intrest in a kit by commenting on this blog. We'll use this barometer to guage the intrest and hence the size of the version one production run.

Squat Thrusts

2005-02-28T22:21:00.000-05:00

Squat Thrusts! are you kidding? How could anyone turn that down? I'm really amazed at how you can make robots exercise for you? How long till it calls you "beautiful"? But really it's a cool robot. I guess it will be walking soon, then before you know it, a car, college...

my brother Kelvin's response to an invitation to see the bot

Squat Thrust Tests
Keith Rowell Design

http://www.mindspring.com/~rowell/MOL003.ASF

Feel the burn.
Bill Hotch

We had a little problem with the ServoMojo losing it's settings on saturday. It worked before the meeting, then when it came time to show off...nothing. Then after the meeting when most everybody had left, bam! (to paraphrase) it snapped back in line and dropped and gave me 50.

We worked over an hour last week stageing a walking sequence when we realized we were breaking the golden rule, "take baby steps" (pun intended). So we backed up a step and went for a "Squat Thrust" movement. This took only 30 minutes or so and we've now tried dozens of motion files based around this motion.

I took it to Stuart's office tonight and we filmed a few routines for the web site. (see the movie)

Glamor Shots

2005-02-04T01:13:00.000-05:00

-KNEWT-
Keith Rowell Design

2005-02-04T00:12:00.000-05:00

family album
Keith Rowell Design

2005-02-03T00:45:00.001-05:00

kjg
Keith Rowell Design

2005-02-03T00:45:00.000-05:00

nbv
Keith Rowell Design

Bob's Script Code in Action

2005-01-25T21:04:00.000-05:00

script tests go well
Keith Rowell Design

Bob has designed an ingenious scheme for defining the walking motions for Knewt. And tonight's test was superb. You can see a movie of the action here: (test movie)

The scheme uses two files. One "motion" file for describing a series or routine of motions that includes motor position, speed, acceleration, and timing (when to act). The second "script" file calls the motion files, running one file many times or several simultaneously. We believe this configuration will do the job and it certainly passed the test tonight.

We can do the "theoretical" motions while making assumptions, but we won't know the actual servo positions and other values until we can test the stuff on the actual robot. You can see a previous mock up movie of the walking motion done on a lego test stand here: (test stand movie)

I ordered washers and standoffs today. There was a technical difficulty the first time ordered (a week ago) so I ordered today over the phone. It must have taken 30 minute's. Anyway, the washers will act as thrust bearings to relieve any rubbing between the aluminum parts at the bearing joints. And the standoffs are a very typical part used in many places.

The pace is really hectic lately, and a hell of alot of fun!

Shoulder Tail Photos

2005-01-22T19:33:00.000-05:00

Shoulder Tail Installed
Keith Rowell Design
The shoulder tail is the removable part of the shoulder plate that makes it possible to install the bearings in the hip bracket. I mentioned these last week but didn't have photos until now.

2005-01-22T19:32:00.000-05:00

More Shoulder and Ankle Parts
Keith Rowell Design

2005-01-22T18:36:00.001-05:00

Wide mode settings
Keith Rowell Design
Upon testing the motors in wide mode, I discovered that they can be made to go the entire 180 degrees, but at the extreme ends of the sweep, they are "erratic". I will test this with more motors to verify, but for the moment I'm sending 7000 to -7000 position commands. This gives about 160 degrees of movement instead of 180, but is stable and there is no motor overheating.

2005-01-22T18:36:00.000-05:00

Servo Internal Stop
Keith Rowell Design

I was noticing alot of motor overheating while testing and opened a couple to have a look. I can't be sure, but my theory is that misaligned servo stops were restricting full motion and causing a stall current condition.

The stops get misaligned by turning the servo horn by hand. The gearbox has a huge ratio with 5 stages, and turning the gearset from the horn causes the geartrain to jump teeth and then the factory settings are out of alignment. Upon opening some motors, I found that there were even a couple broken teeth.

I think I recall being told not to turn these by hand. But I obviously didn't listen as you won't. I'm looking now for the "I told you so!"

2005-01-22T18:34:00.001-05:00

Removing the stop with a dremmel tool
Keith Rowell Design

Instead of trying to find the original factory setting, I decided to remove the mechanical stop entirely. This was very easy with a dremmel tool. I don't think the remaining position sensor (pot) can get "un-set" because it keeps telling the servo to turn until x is reached.

The good news is that "un-dammaged" motors can do the whole 180degrees with no trouble. I will do more testing to ensure that the expanded pulse width isn't doing any damage to the circuitry.

2005-01-22T18:34:00.000-05:00

Lower Outrigger Construction
Keith Rowell Design

The outrigger posts are attached at the ankle and the shoulder plate. The threads on the RC ball joints are so small the the screw steel so hard that it's difficult to drill and tap. Instead, I just cut the threaded shaft short and glued it into the top of the socket head with JBweld.

It's very strong. The outrigger at the shoulder intersects the screw at a 90deg angle though. I'm not sure what to do about that one yet. But suspect more JBweld will be involved.

2005-01-20T21:34:00.002-05:00

circuit board locations 04
Keith Rowell Design

Here the head turn motor is light blue, almost the same color as the background. You can see it just under the front of the horizontal board. The thickness of the boards represents space to plug connectors onto the header pins and all the other stuff on board. It's mostly unused space and will not fill the head as much as indicated. The forward vertical board is space holding for the controller board that hasn't been made yet. It's smaller than the mojo board about 2.5x2". We haven't found an off the shelf board this size for a pic.

Circuit Board Placement

2005-01-20T21:34:00.001-05:00

circuit board locations 03
Keith Rowell Design

We're looking at how to get all the circuit boards into the bot now. We can always put more on the outside, like on the back. But I had originally inteded for the head to hold them all. There is definitely room for the Mojo board even with the head turn motor sticking up higher than I wanted.

2005-01-20T21:34:00.000-05:00

circuit board locations 02
Keith Rowell Design

The width of the boards don't use up all of the space in the middle, but "cut it close" on the corners. Custom boards might be in order. We're looking into it.

2005-01-20T21:33:00.001-05:00

circuit board locations 01
Keith Rowell Design

I'ld like to add the indication of speach by putting a bar graph LED below the nose area. Since the head is to be made of translucent plastic, I pictured having LEDs showing through the skin, but not penetrating through to the outside, except for maybe the eyes. I've still not been able to successfully split the head in two without crashing the model. I'll give that another try this week.

Expanded Mode Mojo Testing

2005-01-20T21:16:00.000-05:00

Bob and I met and tested his code for controlling more than 5 motors at once. It worked fine, he's overcome a few steep hurdles to get to this point. One of which was traced back to the compiler environment not handling a 16bit word as expected and causing the script to abort early.

We tested bob's program with normal range (1-2ms) pulses, then tested the mojo board on it's "extened range" (.5-2.5ms) pulses. That corresponds to -8000 to +8000 on the hex code.

In normal mode, there is about 90deg of rotation from the small servos. In extended mode, we had hoped for a full 180deg. But all we witnessed was about 135deg of rotation. Wheather using 6000 or 8000 didn't seem to matter much.

Tonight I revisited the issue and set expanded mode to 8000 then 6000. I noticed that there was hardly any difference at all. Plus the motors were getting hot. We didn't notice this with the larger motors.

I loosened the screws on one of the motors and it's range increased. So I'm suspecting poor alignment and possibly out of alignment internal stops. (I've skipped teeth on some of these motors, while turning them by hand. This is bad.) If the internal stop is out of position, it will be stalling the motor in middle ground positions. I may try cutting the internal stops out entirely on one to see how far the 8000 will go.

2005-01-17T21:55:00.000-05:00

Motor Designations
Keith Rowell Design

Motor Designations

2005-01-16T23:30:00.000-05:00

Motor Designations 5
Keith Rowell Design

I met with Stuart and Bob last thursday and we set some ambitious schedules for the new year.

Bob requested that the motors be designated for callout by the software and this is what the attaced images are showing.

#1 Head Turn
#2 Balance / Weight Shift
#3 Right Leg
#4 Right Foot
#5 Left Leg
#6 Left Foot
#7 Turn / Hip

Stuart has finished the shoulder tail pieces but I have no photos this week. The slip fit hole for the 4/40 screw that goes through this piece was a bit large, and allowed some play. I happend to have the exact right brass tubing and super-glued a short piece into the hole, then tapped it. The brass being softer than the aluminum, deformed nicely as the screw snugged up, making a very tight fit. There is a small ammount of play left in the alignment pins, but I've left them dry for now. I'm sure they will be absolute once the locktite goes on.

There is only the shoulder plate, neckplate, and foot modifications left to make and we've got big plans to do those quickly. I've ordered mylar washers to act as thrust bearings, these should show up this week.

Tuesday, Bob and I are looking into the programming scheme for simultanious, or "parallel" actions that allow multiple motors to work in unison. Bob's scheme loads all possible motions into a single file with headers dilenating single motions like "left foot forward". Then there's an actions file that will call a collection of motions and tell them when to happen.

2005-01-16T23:29:00.000-05:00

Motor Designations 4
Keith Rowell Design

2005-01-16T23:28:00.002-05:00

Motor Designations 3
Keith Rowell Design

2005-01-16T23:28:00.001-05:00

Motor Designations 2
Keith Rowell Design

2005-01-16T23:28:00.000-05:00

Motor Designations 1
Keith Rowell Design

New Head Design for Knewt #2

2004-12-22T15:04:00.000-05:00

Stuart's head design
Keith Rowell Design

Stuart sent this head design last week. It was designed in SolidWorks and exported in the SAT format first. This format didn't work for import into IronCAD so we tried it next as a Parasolid which IronCAD liked just fine.

Stuart's abilities with CAM as well as the design software shows the kind of skill and talent he possesses. Expect to see these two versions and maybe more, chicken walking around all over the place come this summer.

Stronger Servos for the Foot Motor

2004-12-22T15:03:00.000-05:00

42oz/in foot motor 01
Keith Rowell Design

There was some concern from the beginning as to whether the feather weight servos would suffice for the foot motor, because it's the only motor that experiences the full weight of the robot during walking. The HighTek HS-55 feather servos are rated at 18 0z/in at 6V. http://www.servocity.com/html/hs-55_sub-micro.html Over powering might take it up to a higher torque, just before the magic smoke escapes.

Phillip FitzSimmons did a rough estimate of the forces needed to hold the weight of the bot on one motor and surmised that 15-18 oz/in wouldn't be enough. Not being able to find any servos in the same size format that had more torque, I ordered the next larger size. http://www.servocity.com/html/hs-81_micro.html An even stronger one is available in the same size format: http://www.servocity.com/html/hs-85bb__mighty_micro.html And one with metal gears: http://www.servocity.com/html/hs-85mg__mighty_micro.html

48pitch gears are available for this servo spline shaft too. I ordered a 18tooth pinion and 66tooth spur that will replace the ring and pinion used on the smaller motor. http://www.rcmodels.com/1002-9524.html http://www.robinsonracing.com/catalog/catalog.html
An 18 and a 66.
http://www.servocity.com/html/48_pitch_servo_gears.html
Metal ones are available
http://www.servocity.com/html/48p___32p_metal_servo_gears.html
http://www.servocity.com/html/48p_aluminum_hub_gears.html

The smaller motor with it's smaller spine shaft required a tricky manuver to make the pinion fit. And it requires a pillow block to hold the pinion in place. The larger motor is much easier to fit because of these issues. I would still like to be pleseantly suprised to see the smaller motors carry the day. But I'm planning their replacement just in case they don't.

I'm also looking for travel cases for the knewt. It's overall size is 7x9x12". The pelican water tight case is ideal with the foam inserts but is expensive at over $100. http://www.all-pelican-cases-4-less.com/detail_pelican_1600.html If anyone has access to travel cases for lot less, please let me know.

2004-12-22T15:02:00.000-05:00

42oz/in foot motort 02
Keith Rowell Design

2004-12-22T15:01:00.000-05:00

42oz/in foot motor 03
Keith Rowell Design

Head and Shoulder Plates Finnished

2004-12-15T14:29:00.000-05:00

shoulder plate and head plate with head turn motor atached B
Keith Rowell Design

Stuart has finnished the first shoulder plate, a very complex part to make as we mentioned last week. All of the weight of the bot is carried through the big bearing, and then to the legs, through this plate. It's un believeably light.

The head plate holds the head onto the neck using the same large size bearing. The servo is responsible for the head turning movement via a mechanical connection with the servo horn, through the center of the bearing.

I don't anticipate getting a new camera for Christmas, so WYSIWYG.

2004-12-15T14:28:00.000-05:00

shoulder plate and head plate with motor attached A
Keith Rowell Design

In this orientation, we are seeing the top of the "right" shoulder plate. And the top of the head plate/mtr. Stuart did a fantastic job on these parts and we hope to get a movie of the cutting process this week. It's very exciting to see these parts in the "physical" world.

Mojo Mods

2004-12-15T14:11:00.000-05:00

testing mojo board with leg
Keith Rowell Design

We've recieved the second ServoMojo board and are modifying our set up routine. Until now we were setting all the motor presets with a terminal program directly to the Mojo, and running a pic grogram to control the Mojo afterward. Bob's plan now is to do all the communication with the Mojo through the pic using a "passthru" scheme for testing, and adding a "setup routine" in the pic code to initialize the Mojo on start up.

The Mojo has the set-up saving features that store servo acceleration, speed, trim, etc. But reading, checking, resetting, these from the controller is a step above the manual procedures we've used so far. Brian Dean of BDMicro has been very helpfull as we learn the in's and out's of the Mojo board. Thanks Brian again for your assistance.

2004-12-02T16:44:00.000-05:00

shoulder plate physical
Keith Rowell Design

2004-12-02T16:28:00.000-05:00

shoulder plate model
Keith Rowell Design

Shoulder Plate Progress

2004-12-02T15:45:00.001-05:00

shoulder plate progress

Stuart has begun the really complex parts and I was lucky enough to get photos this week. This shoulder blade part is about 2/3 complete. It started out almost 3/4" thick. The steps used to make this part were 3 setups so far. Stuart set the CNC up for a cut from the "end", using that surface to set up the tools. Then he set up again for one side and cut away the bulk. Then, set up on the other side and cut the holes. It's a very big deal to figure out how you're going to hold the part for cutting. And the surface that you use to touch off the tools for setting up the CNC must be perpendicular so that the various setups will be "synchronized" or the part will have misalignments in assembly. It's quite a complex part. These photos are a disappointment but you can see which part it is by comparing to the model.

2004-12-02T15:45:00.000-05:00

shoulder bracket
Keith Rowell Design

2004-12-02T15:44:00.001-05:00

shoulder bracket
Keith Rowell Design

First Leg Assembly

2004-12-02T15:44:00.000-05:00

leg assembly
Keith Rowell Design

This leg assembly has been togeather since before the holiday but I only got a photo today. We've had the leg and foot parts for some time, it was the ankle hinge parts that completed the assembly to this impressive point. Tape is holding it in a standing position.

Ankle Hinges

2004-12-02T14:54:00.000-05:00

Ankle Hinges
Keith Rowell Design

Stuart made these the week before Thanksgiving. They're very nice and use welding rods for hinge pins. See them in use in the leg assembly above.

Assembly Task List

2004-11-12T18:43:00.000-05:00

top

While the last of the machined parts are being made, I've put together a list of the assembly tasks required. These are tasks that require some minor machine tasks like taping holes to receive screws and cutting standoffs to size. This is the list as it stands now. The numbered tasks correspond to the leaders in the attached drawings.

Mechanical assembly task list

1. Cut ankle ring gear x2
2. Drill & C/sink ring gear x6
3. Tap bottom ankle link for ring gear x6
4. Drill and ream ankle hinges for hinge pin x6 ---11/23/2004
5. Turn bottom outrigger post for ball end x2
6. Cut, Drill, Tap, top outrigger post for ball end x2
7. Make bearing washers from Teflon / nylon type mtl. x22
8. Turn shoulder balance posts for ball end x2
9. Turn hip spreader posts for ball end x2
10. Drill, ream for alignment pins x6
11. Cut neck standoffs x5
12. Cut neck motor standoff x1
13. Tap holes x22
14. Make neck motor / bearing connector
15. Make shoulder bearing posts x2
16. Drill, Tap, Mount leg motor ball end. x2

Machined parts not yet finnished are:

1. hip bracket
2. shoulder plate and mating tail plates
3. leg motor mounts
4. head
5. assembly parts mentioned above

2004-11-12T18:42:00.001-05:00

Iso bottom
Keith Rowell Design

2004-11-12T18:42:00.000-05:00

Iso top
Keith Rowell Design

2004-11-12T18:41:00.001-05:00

side
Keith Rowell Design

2004-11-12T18:41:00.000-05:00

front
Keith Rowell Design

Knewt in IronCAD Gallery

2004-11-01T11:03:00.000-05:00

Looks really good guys..... Keith, you really do have too much time
on your hands.

Paul

IronCAD posted the Knewt Model on their site this week. Thanks to Kevin Devol and IronCAD for the software upgrade.

Brian Dean of BDMicro also responded this week with a very through explanation of the "extended mode" feature of ServoMojo for getting the full 180deg rotation from the foot motors. The settings are made by setting a minimum and maximum position address for each servo. We'll be testing this feature this week.

Philip FitzSimons (who did a great demo of his 5Amp, 30Volt, servo controller at the AHRC October meeting this week "FADC-01") will be helping us look into making a larger heavier, more powerfull, version of Knewt in the near future. (at which time "Knewt" wont be an appropriate name, perhaps "Knossos") How many lbs. of lumbering metal do you think 250watts will carry?

The ankle hinge is under way. I bought polished steel pins some time back for the purpose. But when I got them out this week, they were pitted with rust. The container I put them in must have had something corrosive in it at some point in the past. I have alot of .092 music wire, and we're going to use that as the ankle hinge pin.

View a movie of the lego test jig in action here.

Successful PIC / Servo Tests

2004-10-22T12:37:00.000-05:00

Lego test jig for testing leg motors with Servo Mojo (in the foreground)

Our tests with the PIC and the servo Jig were, after a short detour with the wrong baud rate, successful today. ASCII "motion files" were uploaded to the PIC from the PC using RealTerm. And the program was successfully played back from the pic to the ServoMojo with correct servo motion on the Lego Jig. The Lego test fixture is just a crude mock-up that we use for testing... Next week we'll take a movie of the Lego Jig in action, and do a demonstration for the AHRC monthly meeting. Thanks to Bob for the photos... movie here (1.37m).

Stuart serves up more parts

2004-10-22T12:33:00.001-05:00

More aluminum parts this week

Keith Rowell Design

Stuart joined the circuits and programming team this week with parts in tow. There are now only 7 unique parts left before complete assembly. Unfortunately, these are the most difficult and "intresting" parts, and hence take longer to make. We projected complete mechanical assembly by January / February. Next week might see the ankle hinge added.

The First Step of Real Assembly

2004-10-22T12:33:00.000-05:00

Foot Plate and Bracket Properly Assembled

This image shows the footplate and bracket assembled. This is the first two parts to be more than "fitted" togeather but actually "fastened" with screws. The cutting of the 2D parts being the more simple process, they were rather quickly produced. The final drilling and tapping and
3D parts comming up will take more time. I intend to join the machine class in January to finnish up the assembly. We have parts for at least two complete bots, and assorted parts for a third.

2004-10-22T12:32:00.000-05:00

Parts Arrangement
Keith Rowell Design

Vacation This Week

2004-10-13T22:16:00.000-05:00

Keith Rowell Design

Machining

2004-10-08T02:33:00.000-05:00

Machining

Making tool paths

2004-10-08T02:32:00.000-05:00

Loading Tools
Keith Rowell Design

2004-10-08T02:31:00.000-05:00

Setting up the CNC

Keith Rowell Design

2004-10-08T02:30:00.003-05:00

with coolant
Keith Rowell Design

2004-10-08T02:30:00.002-05:00

Cutting
Keith Rowell Design

2004-10-08T02:30:00.001-05:00

Part holding is tricky
Keith Rowell Design

2004-10-08T02:27:00.000-05:00

the finnished parts in aluminum
Keith Rowell Design

2004-10-08T02:26:00.000-05:00

A partial foot assembly
Keith Rowell Design

Laser Cut Parts Arrive

2004-09-21T02:09:00.000-05:00

Outline files

The activities this week are to test the variables saving features of the ServoMojo board. This includes trim or centering, home position, acceleraion and speed, etc. Also, I'm putting togeather a spreadsheet to store servo locations for all the general motions required. This includes stand, sit, turn R / L, walk forward / back / arc, and transitions between all of the above.

All of these should be easily settable using either narrow or wide mode. Have you settled on which mode you will be using, or perhaps are you using a combination of the two modes?
One way to move to the "home" position is to generate a reset, which will cause the saved positions to be reloaded. Note, though, that the servos will snap back to their home positions as fast as they can at that time. This is due to not being able to know the actual servo positions at reset time. I could easily implement a "Home" command, though, that moves all the servos to their saved positions, without having to perform a reset, which also implies about a 3 second delay as the stored configuration is loaded from the on-board EEPROM. That command would allow the servos to be positioned and also honor the current velocity and acceleration settings, and eliminate the startup delay following a reset. The firmware you have does not support that - but it should be easy to add. I can send you a new chip that you can replace on the board to have that feature. The processor is in a socket to the replacement should be straight-forward.

There's a sample of how the Japanese guys do it here...
http://www.sozbots.com/robo-one/downloads/SoftwareManualEnglish.pdf

Unfortunately, I cannot find a description of the RCB-1's communication protocol in either the software nor the hardware documentation. Without that, I cannot say how easy or difficult it
would be to match it. However, their PC side software is similar to what I envision for ServoMojo. But I don't expect to have that piece in place for some time. I do think it is an important component, and one that I plan to have in place before I present the ServoMojo board for general availability. One hold-up for me has been the lack of a PC virtual machine that runs on my G5 Mac in order to do the development - the current version of Virtual PC supports up to the G4 processor, but not the G5. Just starting recently, however, Microsoft has begun taking pre-orders for the latest version of Virtual PC which finally supports the G5, so at least there is light at the end of the tunnel - but they still don't say exactly when it will be available.
-Brian

I like the name of the software, "Heart to Heart". I don't know the data output format, but I suspect it is'nt compatible with the ServoMojo. Do you know if this is the case Brian? Is conversion worthwhile?

I ordered parts from Pololu in polycarbonate as a test of the material and the service. The Pololu laser cutting service is very inexpensive and their operator Jan Malasek is very helpfull and conscientious. http://www.pololu.com/laser_cutting.html

Not so much can be said about the aluminum watter cutting service DC waterjet. These guys didn't respond to emails, and after bugging them a few times they finally came back with estimates. http://www.dcwaterjet.com/index.shtml

Pololu can't cut metal nor mat'l thicker than 3/16". So I only sent them the parts that were 2D and 1/8" thick. Their charge for these parts was $28, and that includes the polycarbonate material, checking the file for errors and getting back to me on fixing them...I really like using them. I've not yet ordered the parts for the 1/4" material. Stuart is considering making them locally so we'll have one all aluminum bot and another plastic/aluminum hybrid.
The same parts cut in aluminum from DC water jet is $90. The 1/4" parts are $114. (not including material) Emachineshop.com was $118. All the 1/4" parts require extra machining after cutting out the outline.

2004-09-21T02:07:00.000-05:00

The polycarbonate is considered bullet proof by the battlebot guys, but not suprisingly, when you cut it this thin, it's flexible compared to metal. Dale suggested that this could be an advantage, absorb shock, etc. Re-Ordering in 3/16" mat'l is an option. Stuart's aluminum version will kick this one's butt.

2004-09-21T02:03:00.000-05:00

Side

The following is the central body made up of the back plate, battery retainer, balance servo, hip/turn servo, shoulder bearings w/mounting flanges, the neck standoffs, and the batteries