Mar 22, 2009

Dual NXT Biped

Check out this huge build from 222Doc.

It has 7 degrees of freedom, and can walk up a step of 1.5 inches in height. Notice how it moves the NXT's from left to right to shift the centre of mass over the supporting foor.



--
Damien Kee
www.domabotics.com

5 comments:

222Doc said...

Hello, I would just add that in this video it is being controlled by PF/RC. This was the first testing to see if it had enough power(not break gears able to recover from a single knee bend)It is to be a two nxt SOON in an autonomous mode. I have replaced the PF with NXT motors and few more tweeks as well.In the track gear platform. I even think it is possible to do this with 1NXT and still have 7DOF. one half nxt the other PF with Touch/lightsensors sensors as rotation sensors. I have alot to do on this still.

Thanks for the Spot light,

Doc

BlueToothKiwi said...

There are very few people who can make such a large stucture with TECHNIC and it is an art in itself. I take my hat off to this model from a structural point of view.

222Doc. If you have not taken this apart, Your Next challenge is to see if you can utilize the NXT to do some of the actions within a step. You got four sensor ports between the two NXT's up there. Touch sensors are great for these when used with PF motors. The other option is to use the IR-Link to control some of the PF motors from NXT (cant see if you are doing that already). A tilt sensor might also be useful if you dont want to do dead reckoning and get the rotations wrong and topple over!

Well done!

222Doc said...

BlueTooth,

No wont be taking this apart any time soon. For many years I have been working on getting a Biped to even be able to take one step up a stair. When i finallly did, even in an R/C technic mode it was a break through for me.

In this video I had one mistake noted by my son, the step was 2 inches tall, guess my eyes are not as good as they used to be.

I now have the IR link set up in the head, and have that SM/PF using a rotation sensor made from a light sensor that is taking readings not from the motor but from one of the gear reduction sections that turns slow about 15 to 1 of the motor about 1/2 inch of travel.

Now to figure out how to get the second next to control 3dof as the slave and this should work, well, i can not count how many times i have thought that and run into a few hundred other issues!

I am very happy with these latest articulation joints at 5 studd wide(from turn table to turntable inside) it is the smallest and most powerful I have ever made.

BlueToothKiwi said...

Sorry - I wrote my last comment before I saw your first comment (while it was awaiting moderation).

Wow. That many degrees of freedom with a NXT is pretty hard - especially when the model need to be dynamic (carry itself!).

I was redesigning my Grader last night, where I used a turntable and 5 linear actuators to make the Moldboard NXT controlled. I am finding the limitations of 4 PF channels being controlled from one IR-Link and NXT and the downside of not having rotation sensor in PF motors - So I am also contemplating replacing the PF motors with NXT motors - but scared of the extra weight of the additional two NXT's.


So I can probably understand what you are up against.

There are also some lags you need to cater for as you have two NXT's communicating with each other by BlueTooth. You might have to consider something other than NXT-G (e.g. pbLua / NXC)

Good luck!

BlueToothKiwi said...
This comment has been removed by the author.
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