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Sienna
03-28-2008, 08:30 PM
First attempt at walking, before I was able to get it kicking off with a leg:
YouTube - Tripod First Walk

After much tweaking in SEQ, I was finally able to figure out where the robot needed to be to have a controlled kick and fall. At this point then the robot could actually walk:
YouTube - Tripod Actually Walking!

My original spammy glee over getting something accomplished:

It walks it walks it walks!

*runs around excited*:tongue:

EDIT:
For some reason this video seems to have gotten lost. huh.
YouTube - Tweaked Forward Kinematic Sequence
This isn't new, this was done way back when the others were.

JonHylands
03-28-2008, 08:48 PM
That's really awesome, Sienna... I've often wondered how a decent tripod gait would work.

- Jon

tom_chang79
03-28-2008, 09:06 PM
That is one of the most awesome walking I've ever seen... You should enter this into the project contest... Great job Sienna!

DresnerRobotics
03-28-2008, 11:37 PM
http://www.youtube.com/watch?v=4FABBKPoNO4

It walks it walks it walks!

*runs around excited*


Absolutely amazing. /applaud

archcvd
03-28-2008, 11:53 PM
That's so crazy awesome! Reminds me of Hunters in Half Life 2: Episode 2

http://upload.wikimedia.org/wikipedia/en/b/b2/Hl2ep2_ministrider1.jpg

JimH
03-29-2008, 03:51 PM
Very cool. Great job!

LinuxGuy
03-29-2008, 04:58 PM
Sienna,

I think this has to be one of the coolest robots I have seen. There is way too much activity in hexapods. We need more activity in those that are not often thought of as challenging and interesting.

The tripod is definitely in the interesting catagory though!

Maybe I should tinker with quadrapods, which is actually needed to build on for another idea I have.

8-Dale

Droid Works
04-04-2008, 10:12 AM
Excellent work! Its always nice to see something new and innovative.

Sienna
04-04-2008, 04:43 PM
Thanks everyone! *hugs*

darkback2
04-05-2008, 08:30 AM
Ok...so first of all, really cool robot.

1) What made you think of making a three legged robot? I guess I was thinking that you have the balance issues to deal with, but having only three legs would give you a stable platform in the least number of contact points...so more to the point, what are the direct advantages to three legs, vs four...or six?

2) What are the future plans for this guy?

Way cool.

DB

Sienna
04-05-2008, 10:57 AM
Initially, I was planning on building a hexapod. However, we all know hexes take a lot of money to buy all the servos. So, what I did instead, was come up with a "growth plan" as I bought more and more servos. The plan at nine servos was to build a tripod, for no reason at all but as a science experiment. (After all, if it didn't work, it was only intended as a stopping point to a hex right?)

Well, it worked. And now I am kinda liking my tripod, I think I will keep it a lot longer.

So, what are my future plans for it?

1) The most immediate is to add a SFE 6DOF IMU to it. I think I should be able to afford one of those pretty soon. The reason is that I want to give the robot the ability to balance on two legs, while manipulating the third. (right now the robot "jumps" the third leg, and has only a limited time before the robot falls back onto that leg) This will open up a whole new range of gaits and abilities.

2) I want to work on IK code for the robot, so I can stop using FK animations for the walk.

3) I want to move that code onto a Hammer embedded into the robot.

4) I am going to be adding sensors and LiPos, etc, as needed, to get the bot off the tether and out autonomously into the real world.

5) I want to play with other leg styles. I am considering adding a fourth axis to each leg.

So, I have quite a bit of work ahead of me. This may turn into my primary bot, and I may never reach a hex.

metaform3d
04-05-2008, 03:11 PM
That's really excellent! I played around with tripods as well, with not nearly the same success.

LinuxGuy
04-05-2008, 06:01 PM
Well, it worked. And now I am kinda liking my tripod, I think I will keep it a lot longer.
I think you should keep the Trippy little Tri-Pod. :happy: I think you could still do more with it, especially once you get it moving around autonomously. :happy: I am truely impressed!


3) I want to move that code onto a Hammer embedded into the robot.
Speaking of Hammer, I have mine booting from flash now (14 MB Flash available) and nothing else. I have about 25 MB RAM available. :happy: At this point, W.A.L.T.E.R. is fully self contained, booting from flash (including Python 2.4.2!). Next step is getting WiFi working. Current kernel is 2.6.25-rc7-hammer.

Time to go into software development and interfacing mode! :happy: I'm going to connect my Bluetooth DIL module to /dev/ttySAC0 (main console) and the SSC-32 to /dev/ttySAC1. I sure wish we had access to that third serial port.


4) I am going to be adding sensors and LiPos, etc, as needed, to get the bot off the tether and out autonomously into the real world.
I am soooooooooooooo looking forward to seeing the little tri-pod moving around on his/her own. Have you named him/her yet??


5) I want to play with other leg styles. I am considering adding a fourth axis to each leg.
There is a lot you can do here. You have me tempted to build a quadrapod now. Maybe I will try a Tri-Pod and then upgrade to a quad..


So, I have quite a bit of work ahead of me. This may turn into my primary bot, and I may never reach a hex.
This is work? Nobody told me that! :happy: Have you considered building a second tri-pod and connecting the two to make a hexapod? It would be a bit different than what is usually seen in hexapods, and there are several different ways you could connect two tri-pods.

8-Dale

crabfu
04-19-2008, 03:14 AM
That is really cool... :)

-Crabfu

tom_chang79
04-21-2008, 09:44 AM
Crabfu, I saw your vid of your tripod walker, are you still working on that unit?

crabfu
04-21-2008, 01:57 PM
Crabfu, I saw your vid of your tripod walker, are you still working on that unit?

Yeah but it's nothing like Sienna's 3 legger - that's just too cool... mine barely moves around, very limited mobility. Feel free to ask and comment about my work on my thread, this is Sienna's post :)

-Crabfu

Sienna
05-04-2008, 06:56 PM
Ok! Need some more suggestions.

For version 2 of the tripod (named Amy), I am having trouble deciding on a 'look' for the superstructure. Size wize, I am looking for something about 10" in diameter, which will cover most of the undercarriage when it is retracted.

Any suggestions?

Thanks!

LinuxGuy
05-04-2008, 07:11 PM
For version 2 of the tripod (named Amy), I am having trouble deciding on a 'look' for the superstructure. Size wize, I am looking for something about 10" in diameter, which will cover most of the undercarriage when it is retracted.
How about a basic triangular shape, but with an outward curve instead of straight on the sides? Inward would be the way most would probably do it, so be different. :happy::veryhappy:

8-Dale

Sienna
05-24-2008, 03:49 PM
Ok, more votes please. Which of the following base mounting options looks better?

Inline with the legs:
http://forums.trossenrobotics.com/gallery/files/1/6/8/5/tripod-deck_inphase_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=275&c=newimages)

Opposite the legs:
http://forums.trossenrobotics.com/gallery/files/1/6/8/5/tripod-deck_outphase_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=276&c=newimages)

Thanks!

sthmck
05-24-2008, 03:57 PM
I like the way the inline one looks.

crabfu
05-24-2008, 04:38 PM
I strongly prefer the opposite mount, it balances everything out and shows off the legs :)

-Crabfu

Wingzero01w
05-24-2008, 04:40 PM
Mm... i think ill say opposite.

Zenta
05-24-2008, 05:50 PM
Hi!

Very nice and shiny design. CNC made? I must say I love this project of yours! Very creative!

Ok, more votes please. Which of the following base mounting options looks better?

Inline with the legs:
http://forums.trossenrobotics.com/gallery/files/1/6/8/5/tripod-deck_inphase_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=275&c=newimages)

With the inline version I would recommend a bit smaller base plate. It looks like the corner of the plate may get in conflict with the tibia part?


Opposite the legs:
http://forums.trossenrobotics.com/gallery/files/1/6/8/5/tripod-deck_outphase_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=276&c=newimages)

Thanks!
This opposite design definitely looks very cool :p
Thumbs up for the opposite way!

-Zenta

Sienna
05-24-2008, 06:18 PM
Thanks everyone for the votes! Looks like opposite is winning! That was kinda my preference too, but wanted a second opinion.

Of course, the one in the photo has some errors in it. Minor ones, but errors the same. I can't wait until I get to show the new one I designed to replace it :D


Very nice and shiny design. CNC made? I must say I love this project of yours! Very creative!
Laser cut acrylic. I thought I established that I couldn't cut a straight line with a ruler! I outsource um... everything :P


With the inline version I would recommend a bit smaller base plate. It looks like the corner of the plate may get in conflict with the tibia part?
Yes, you are right. At full extension, there is a bit of rub.

metaform3d
05-24-2008, 07:42 PM
I wasn't sure about the out-phase mounting but it's growing on me. You could use the exposed points to mount feelers or other sensors. I love the round circuit board! I hope it's still visible after the rest of the decks are in place.

Laser cut acrylic is my material of choice. Much as I enjoy using a milling machine or lathe, I never quite get exactly what I want. But if I design flat pieces so they assemble correctly in 3D then I get the correct result every time. CNC cuts out that pesky middleman -- your motor skills!

Sienna
06-05-2008, 06:29 PM
Hehe... The new deck :)

http://forums.trossenrobotics.com/gallery/files/1/6/8/5/tipod-amy-build-11_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=355&c=3)

She is coming along!

tom_chang79
06-05-2008, 08:20 PM
That has got to be one the most aesthetically beautiful decks I've ever seen. Awesome! :D

LinuxGuy
06-05-2008, 09:10 PM
Wow, Sienna! You definitely have an eye for style! This is a nice deck!

8-Dale

Zenta
06-06-2008, 01:12 AM
Fantastic, nice curves and beautiful design Sienna!
How did you come up with this? Are you in the designing business too?
Anyway, you sure got a great talent for making awesome bot's.

(Just one little thing, I would recommend taking the picture with a more neutral background.;))

metaform3d
06-06-2008, 01:39 AM
I like the design a lot (and disagree about the choice of background). With some small tweaks you could make a walking biohazard (http://blogs.nature.com/news/thegreatbeyond/biohazard.png) sign, which would be awesome.

Adrenalynn
06-06-2008, 01:58 AM
The sharp points are strangely attractive. I do like it!

crabfu
06-06-2008, 04:26 AM
looking really sharp Sienna!!! sweeeeeeeet :)

-Crabfu

Sienna
06-06-2008, 06:57 AM
Thanks everybody!!

How did I come up with the design? I dunno, I was playing around in Inventor. And no, I have no design experience. I just wanted something a little more exciting then the old deck.

As for the background: This was just a candid in work shot. Which means it is on the desk :P When she is all done I will take a picture somewhere 'flat' :)

Raul
06-06-2008, 05:03 PM
Hy Sienna.
Your project is nice i love it, but i like more the project of crabfu http://www.crabfu.com/swashbot/
Is small and fast and is simple the kind of project that i can do more easy hehe.

Your project is difficult to do, i desire that i can do it hehehe, congratulations for the work.
continue your execellente project.

bye

Adrenalynn
06-06-2008, 05:33 PM
Hi Raul,

I love Crabfu's Swashbot too (he's a regular contributor here on the TRC and has posted videos here of the build process), but you really cant compare the Swashbot and Sienna's tripod. Sienna's tripod is a real computre controlled platform for experimenting with sequencing an effective tripod gate.

I think Mini Coopers are cute. But I wouldn't want to compare one to a Raptor fighter plane...

No offense to Crabfu - he knows I'm in love with his cute little Swashbot, but he has a Mini Cooper and Sienna has a Raptor...

LinuxGuy
06-06-2008, 08:44 PM
Fantastic, nice curves and beautiful design Sienna!
Are you talking about the robot, or about Sienna? ;) ;)


How did you come up with this? Are you in the designing business too?
Anyway, you sure got a great talent for making awesome bot's.
She sure does!

8-Dale

Raul
06-17-2008, 07:41 PM
Hi Raul,

I love Crabfu's Swashbot too (he's a regular contributor here on the TRC and has posted videos here of the build process), but you really cant compare the Swashbot and Sienna's tripod. Sienna's tripod is a real computre controlled platform for experimenting with sequencing an effective tripod gate.

I think Mini Coopers are cute. But I wouldn't want to compare one to a Raptor fighter plane...

No offense to Crabfu - he knows I'm in love with his cute little Swashbot, but he has a Mini Cooper and Sienna has a Raptor...hi Adrenalynn,

I did not want to offend nobody:sad:, but i donīt any project yet i am a noob :veryhappy:, i donīt konw the difficult taht is the construction of this robot, i didnīt compare the projects, i want say that the project of Sienna had lot of work and the Swashbot is more easy to do.
i donīt have the perception the work, the time sepend time that Sienna had. i see the work of Swashbot because he had videos.

Sorry if i offend somebody.

Cumpliments

crabfu
06-17-2008, 08:08 PM
I see robots as art... and with any art, it's subjected to opinions... But the fact that these 2 projects have 3 legs, is about as far as they have in common.... one is a real complex work of art, amazing attention to detail, and pulling off a very difficult, and unusual mechanic. Mine is just a simple toy, I wouldn't even go as far as calling it a mini cooper... maybe a paper airplane :) Let's not compare and judge which robot is "better", but appreciate each project for what it is.

I know you are not trying to offend anyone Raul, but keep in mind we all spend a lot of effort in making these machines, and to post and say that another project is better for you, can be easily taken the wrong way... you can see that can't you? :) So keep in mind that this is a small tight community, we are all here to learn and share, not to compare and judge :) I for one am a huge fan of Sienna's design there, and love the fact that it is so different and creative..... and can't wait to see more!

-Crabfu

Sienna
06-17-2008, 09:44 PM
I wouldn't worry about it. There is no secret police here that will arrest you if you prefer one project over another :) Hell, even I am envious of Crabfu's stuff :D

Anyway, very little progress lately... Very soon I will run out of excuses for why I am not coding. When that happens, then you might see some progress :P

In the meantime, one more excuse knocked down:
http://forums.trossenrobotics.com/gallery/files/1/6/8/5/hammer_rdp_v1rc_thumb.png (http://forums.trossenrobotics.com/gallery/showimage.php?i=397&c=3)

Wingzero01w
06-17-2008, 09:54 PM
So this is what you and robotguy have been working on. Is this going to be manufactured by tincantools?

Sienna
06-17-2008, 10:45 PM
I am not sure if my design will be used as is or not. If anyone has feedback, I would love to see it here:
http://www.tincantools.com/forum/viewtopic.php?t=387

But yes, I am hoping TCT can make this or something similar!

Wingzero01w
06-17-2008, 11:08 PM
I also wonder were robotguy is, he usually make a post at least once per day...

LinuxGuy
06-18-2008, 02:41 AM
I also wonder were robotguy is, he usually make a post at least once per day...
I am here, and reading the forums every day. I just haven't been well these past couple of weeks, so have been keeping quiet.

I think Sienna's trippy little tripod is awesome also! It's definitely one of the most unique autonomous robots around. I hope it wins a contest! I will have something else unique to show soon also. ;)

Thanks for asking. :D

8-Dale

Shevek
04-20-2009, 05:11 PM
Amazing robot, the gait is really cool! Congrats on getting it to walk.

Grand Robot Master
04-21-2009, 07:02 PM
I had my own plans to build a tripod. Something a little more "War of the worlds" type, hopefully.
any advice?

Sienna
04-22-2009, 05:10 AM
I had my own plans to build a tripod. Something a little more "War of the worlds" type, hopefully.
any advice?
Be patient? And get a lot of padding if you are testing your gait on an elevated surface... (Yes, my little tripod did manage to fall off the desk I was using and crash into a pile of spare parts, don't repeat my mistake)

Seriously though, I don't have any good advice on this. If you really want to build a tripod, then you will need some decently strong servos, and preferably knowledge of an accelerometer. If you want to build a "WotW" style tripod, I assume then your feet are going to be "points" (like mine), which is going to make an accelerometer (or multiple accelerometers) a must. Your mechanics are also going to be different then mine, as your legs will originate "down from the bottom of the robot" where mine come "out from the sides of the robot".

When I was thinking over control algorithms in my head, the only method I thought of that made sense was using a model of the robot to do inverse kinematics. If the robot "knows" where its feet are (based on joint angles, leg lengths, etc) then it can draw a "line" between two feet. If the center of mass (requires more calculation or a good guess) is placed over that line, then the robot should be more or less stable. It will constantly be tipping one way or another perpendicular to that line, and thats what the accelerometer should be reading. As the accelerometer reads the robot is tipping, that will have to be turned into a corrective action (using the IK model again - ideally you don't want to move the feet when you are swinging the robots CG around) to bring the robot's CG on the other side of the line to counteract the tipping.

I think there are notionally two ways to do the accelerometers. You could get a two or three axis accel, place it at the CG, and then read which direction gravity is pointing to find which direction you are tipping. Or you might be able to place three, one axis gyroscopes or one axis accelerometers on each "side" of the robot, and you might be able to use those one at a time to read tilt. (The first method is more beneficial I think, but it requires more math time then the second)

All in all, building a tripod is going to be very challenging I think. Maybe start off with an inverse pendulum or balancing bot to get the hang of reading an accelerometer?

Grand Robot Master
04-23-2009, 07:20 PM
how hard is a balancing bot?
as you have guessed, i'm not really a robot master, only in name.
i have little programming skills, but some mechanical and eleclotronic experience. (less of the latter)

Sienna
04-23-2009, 09:48 PM
how hard is a balancing bot?
as you have guessed, i'm not really a robot master, only in name.
i have little programming skills, but some mechanical and eleclotronic experience. (less of the latter)
Two motors, an accelerometer, micro controller, battery... I dunno :P
Google is your friend here, I haven't built a balance bot yet. :(

Adrenalynn
04-23-2009, 10:21 PM
I have a pseudo-segway about done. You substituted "accelerometer" for "Gyroscope" - do you know how to make that work well?

Sienna
04-24-2009, 08:38 AM
I haven't studied balancing bots really, so I wasn't thinking to hard.

I assume a single axis gyroscope is what you are using? In which case, I imagine you look for the gyro to read "not zero" (as anything not zero would indicate that you are falling in one direction or the other).

With the accelerometer, I was thinking of a two axis accel, where one axis is pointed down, the other towards the "front". When the bot tilts, the direction of gravity changes, and can be measured by using the two axis as vectors. I was assuming (again, because I have never studied balancing bots) that as long as you know where gravity is, you know how to compensate for it. Of course, now you have me thinking, and that second axis would be feeling as well the acceleration of the bot moving, which would throw off measuring gravity unless you had some way to measure forward speed too. hmmm...

Adrenalynn
04-24-2009, 11:33 AM
Two things to note -

Accelerometers need change - they're all about change. :) There are challenges with them having their steady-state rise or fall if they're kept in one position. Gyros are an absolute measure.

Moving forward, backward, left/right (turning) is all about falling. It's a constant state of controlled fall. If you fall too fast the wheels can't get under you in time. Too slow and you oscillate.

Sienna
04-24-2009, 05:58 PM
I disagree. Accels measure gravity (which is a constant acceleration) quite well, in their steady state. (At least thats been my experience.) What are these challenges you refer too?

I also don't believe gyros are an absolute anything. They too rely on change (just rotation instead of translation). Gyros cannot measure anything absolutely, that is the function of higher order algorithms to integrate the change they measure into a position.

Adrenalynn
04-24-2009, 08:03 PM
A gyroscope measures the angle - an accelerometer measure acceleration on an axis. If you're in a steady state the accelerometer's acceleration is zero even when the angle is not.

One is used for static acceleration, the other for dynamic. For a robust solution you combine them. For something that just works, a gyroscope is adequate, an accelerometer isn't.

Sienna
04-25-2009, 07:22 AM
Can you please provide a part number for a gyro that measures absolute angle? The only ones I can find measure angular rate (e.g., you still need to integrate their output and account for drift in order to find "down").

And as I said before, in a steady state (not moving) an accelerometer still senses gravity if the axis isn't completely parallel to the ground. I have one of the cheap triple axis accels right here in front of me that I have been playing with for the past two weeks, and I can watch as the three outputs vary with the tilt of the PCB board.

And I agree for a robust solution you combine them, but that starts getting pricey. (Less so nowadays then it was but still)

Grand Robot Master
05-13-2009, 08:08 PM
i just actually watched the video and that's more or less what i wanted to do. picture something like your robot only rounder, taller, and spindlier. then come the airsoft guns, which i may switch out for a "heat ray"(tiny flamethrower) after the robo-games. (run little victorian people run!!!!!!) I'l see if i can scan a schematic.