Author Topic: Stair climbing robot  (Read 7281 times)

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Offline paulstreatsTopic starter

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Stair climbing robot
« on: July 24, 2007, 07:29:31 PM »
Does anybody have any plans or designs for a stair climbing robot that i could modify? it doesnt have to be a bi-ped and id rather if it wasnt, as long as the design could reliably climb and descend stairs.

thanks.

Offline Steve Joblin

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Re: Stair climbing robot
« Reply #1 on: July 25, 2007, 09:52:49 AM »
I haven't actually built one myself, but a quick Google search turned up some interesting sites...

You can go with a "tread" approach (think military tank) where the treads are longer than the distance between two outside corners of the steps.
You can go with a "whegs" approach (google on "whegs" to get different designs)
You can go with an articulated frame approach using six wheels

Check out these to get started:
http://www.stairbot.de/en_beschreib.htm
http://www.martinbuehler.net/theses/Ned_Moore_thesis.pdf
http://asl.epfl.ch/aslInternalWeb/ASL/publications/uploadedFiles/Octopuspaper.pdf
http://www.isd.mel.nist.gov/projects/USAR/2003_competitions/Cedra%20Awardee%20Paper.pdf

Offline paulstreatsTopic starter

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Re: Stair climbing robot
« Reply #2 on: July 25, 2007, 06:10:40 PM »
Thanks, I never even thought about using something like whegs, but this type of wheel/ leg design might just work for what i want.

Offline Robotboy86

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Re: Stair climbing robot
« Reply #3 on: July 26, 2007, 03:18:34 PM »
I am desinging(google sketchup) a robot with 4 legs controlled by servo's that can climb stairs and other various obstacles.  If you want I can upload it later.. be warned though its only half complete and a lot of things would still change on it..

As far as controlling the legs, I am borrowing designs that use gears to do it.  Essentially you place gears at the edge of each leg segment and have them set a set distance apart.  Then link the metal legs with some kind of metal bar that can rotate.  Because the gears simply move around eachother, the segments never move farther or closer to eachother.

Let me know if you want ot see a 3d model

Offline paulstreatsTopic starter

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Re: Stair climbing robot
« Reply #4 on: July 26, 2007, 05:09:18 PM »
Yes please,

 I would like to explore and investigate as many design types as possible before settling for one that meets my needs.

 thank you

Offline Robotboy86

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Re: Stair climbing robot
« Reply #5 on: July 26, 2007, 05:19:41 PM »
I'll upload it when I get home :)

Keep in mind, you can defintelly scale my design down to say 6 inch tall legs and avoid lots of the headaches i am experience with torque requirements :)

Offline Admin

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Re: Stair climbing robot
« Reply #6 on: July 30, 2007, 07:37:39 PM »
Does it need to be autonomous (much harder for stair climbing)?

What about the iRobot packbot design?

[youtube=425,350]gEllxIMl73k[/youtube]

[youtube=425,350]OTZOwvFFGhU[/youtube]

Offline paulstreatsTopic starter

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Re: Stair climbing robot
« Reply #7 on: July 31, 2007, 10:13:21 AM »
It does need to be autonomous, and capable of overcoming everyday obstacles - stairs being my main problem at the mo. I want to try to steer clear of cat tracks.

The "whegs" approach would work if you optimised the leg length for stairs, but unfortunateley not all stairs have standard riser sizes, and i have a feeling that making "whegs" which can grow/ shrink wouldnt be that easy.

Quadrapeds also wouldn't be too easy either since dogs have problems on stairs.

Im considering something like a caterpillar design which can lift the front section onto a step and them manipulate its body to pull the rear end up.

Offline alpha_geek

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Re: Stair climbing robot
« Reply #8 on: August 06, 2007, 11:21:10 AM »
Hi I have been thinking about stairs for my next robot (someway off yet) but I have had a few ideas.

What I am thinking of would be heavy, require some good motors and allot of gearing. My plans have the robot at about 4 foot tall.

My plan uses the tri-star wheel design. I can post a few links. but it would require some thinking.

http://orionrobots.co.uk/tiki-index.php?page=Tri+Star+Wheels&PHPSESSID=25bb9a0c56fe6befb39f74f7b03536d5

the robot would have 3 wheels (each wheel being a tri-star) the 2 at the back would be driven as a differential drive, but not in the normal one motor per wheel arrangement. instead I intend to use an adder-subtracter gearing system

http://orionrobots.co.uk/tiki-index.php?page=Adder+Subtractor+Drive

The front wheel would also be a tri-star, but the drive to the wheels and the drive to the tri-star would be separate, and able to brake independently. The tri-star would have to be able to lock so that it runs free on one wheel of the three, while on flat ground. This is so that the wheel (in fact whole tri-star system) can spin like a caster would. Finally the two back wheels, and the front wheel would have to be connected via a Y shape (where the bottom of the Y is the front wheel and the two points at the top are the back wheels) which can pivot at the center. This would allow the front and back wheels to be brought closer together and further apart for different stairs, and to be able to raise and lower the height of the robot. The main body of the robot would then be attached to a forth and final beam attached Perpendicular to the center of the Y (coming up off the screen). This alows the robot to lean forward and back to ajust balance. This will help allot when coming down steps, as well as being able to push the front wheel out in front.

It sounds complicated, because it is, and I have put much thought in to this. You would have to calculate the size of the robot, based on wheel sizes to deal with stairs.

http://www.fas.harvard.edu/~loebinfo/loebinfo/Proportions/stairsdoors.html
http://www.visi.com/~dc/tristar/
http://www.visi.com/~dc/tristar/bkground.htm

 


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