Gap crossing robot

[nxtreme]

I spend some time on the Lets Make Robots website as well as MindBoards. While I haven't contributed much, I have learned lots there, and the group of people is always growing, which means that there always is new content, as well as a fun group of like minded people. A member of the LMR community by the name of winfieldrobotics created a contest called "Cross the Gap" a couple months ago.

The aim of the contest was to make a robot that could fit inside a 12"x12"x12" box, unfold if necessary, and cross a 12" gap between two tables, chairs, whatever. The rules where quite lenient on most things, like the robot didn't have to fold back up once it had crossed the gap, and there weren't really any restrictions on the method of crossing except that it had to move every part of the robot over to the other side, so no catapults .

I (as always) was fairly busy with several projects as well as life in general, so I left it to the last minute, but I finally did get my entry... entered. In principle it was a very basic design but it's the little details that take the most time. Programming was fairly easy, just a lot of experimenting to get the right values, as this robot needs to be fairly precise in it's movement. After I had it all working like I wanted it to (~11 PM of the day before the cut off date) I started working on the video and finally finished it around 4:30 AM on the cutoff date. That's why the captions, music and filmography are somewhat lacking, as this brain doesn't work to well at that time. Oh, and did I mention that was also the first time I'd ever used Windows Live Movie Maker?

Anyways, enough chatter. Video here (It'd be nice to be able to embed Vimeo videos...) and pictures here. I didn't take the time to make sure the pictures ended up looking nice, I was in a rush. If there are any questions, just ask!

-EDIT- I didn't notice it until I had uploaded the pictures, but the program I used to scale down the size of the pictures appears to had added a bit of a weird "ghosting" effect to the pictures. Well, they'll have to do.

[doc222]

Well done and it did rather fast as well.

doc

[dimasterooo]

Good job! It's fun to see it go, especially the part where the little yellow thing comes out the back (what is that?).

[mattallen37]

Very cool robot

...the little yellow thing comes out the back (what is that?).

I think it is one of these.

[dimasterooo]

oh. thx. I didn't really make myselft clear though . I mean "What's it for?". Sorry

[mattallen37]

I believe it's to support the rear, until it get far enough across to balance itself on the second chair (or whatever it is).

[dimasterooo]

ok, that makes sense. thx again

[nxtreme]

Well done and it did rather fast as well.

Thanks, that means a lot coming from The Master of Destruction, Doc222 . I was actually quite surprised at how fast it crossed, though freshly charged batteries do help.

Good job! It's fun to see it go, especially the part where the little yellow thing comes out the back (what is that?).

Thanks! I did have fun watching it go, even though I had to run it about ten times (and that was after I thought to charge the batteries...) to get a near perfect run. Even then, the camera man (me) messed up . And yes, Matt is right. The yellow piece (from the yellow cherry picker) is there to keep the bot from falling backwards into the gap, though it did mess up and fall a couple times... and yes it is a chair, three of them actually.

I intend to create a bloopers video, however, like I said before, I'm quite busy and it appears for now that I will be until the end of time. So don't hold your breath .

[mightor]

Wonderfully simple in its approach, great job. I like the weight shifting with the NXT brick

- Xander

[nxtreme]

Thanks! I at first thought I'd have to add another full sized arm to the back of the robot to get it crossing successfully, but the weight shifter seems to have worked. I also had problems with the amount of motors I needed. Two for the wheels, front and back, one to drop the front end of the 'bot, one for the weight shifter and then one for the small arm at the back of the 'bot. And I needed to attach all that to one NXT brick.

Then I remembered the post by Brian Davis on TheNXTStep about peoples tendency to over-engineer things like this. Figured I'd have to simplify a bit . I ended up using port A for the big arm, port C for the winch, which also makes the small arm drop out the back, and port B for the two drive motors split through three NXT to RCX converter cables. I probably shouldn't be powering two motors through one port, but I figured that they only run for a couple seconds, and they are no where near stall conditions.

Speaking of which, I wonder how hard it would be to install a heatsink on the motor drivers...