Oct 22, 2006

Reader submission

I received an email from Karl with some pictures and a link to a video... some really nice design work with a mixture of Technic and Brick pieces... and marbles. I'll let the video speak for itself.

Video

Pictures

10 comments:

Jim Kelly said...

The axle and gear that you use to tip the releases for the marbles... that's the kind of simplicity I love to see in designs... great work, Karl.

Jim

Brian Davis said...

One curious thing: he seems to use the light sensor to detect when a marble holder is in position (i.e., to sense the stop positions of the platforms). Odd, as since he's using the NXT motors to drive them, I should think he could use the motor encoders to do this right in the software. I'm not sure he's taking advantage of the full abilities of the NXT here, or maybe the precision isn't quite up to the task.

This is a great integration of the NXT, and the video is very well done. I think this design originated with Iain Hendry in Canada about four years ago, but I love the implementation every time I see it. Nicely done!

--
Brian Davis

Maniac was under the impression that he said...

Wow...

The design is quite an accomplishment, I'd love to see a wholly mechanical version of this...

Karl said...

Hello Brian.
I used the light sensor as I couldn't work out how to use the rotation sensors properly, if someone could do a tutorial, including gears, that'd be brilliant.

The whole thing was inspired by an RCX version I saw on YouTube.

Karl

Will George said...

KARL are you a packaging Engineer?
REALLY REALLY REALLY nice work! AND it works!

Ian said...

>The whole thing was inspired by an RCX version I saw on YouTube.

I saw that too, and had no idea what that was. The way of releasing the marbles is very innovative, I would not have thought of that.

Brian Davis said...

As to using the rotation sensor properly, the easiest way to do it is have the NXT in contat with the computer (via BT or USB), and then select a Motor or Move block so you can see the configuration pane for it at the bottom. On the left edge of that pane is the feedback values from the motors, so you can see exactly how many degrees of change it will take to rotate those turntables exactly 90°. Then, use this value for a Move or Motor block of fixed duration (in degrees).

The only problem I can think of is if, perhaps, 90° of rotation of the turntable does not correspond to some integer number of degrees of rotation of the motor, there might be a slow "drift" over time. I can think of two way to fix this too: (a), fudge a few degrees every, say, 10 cycles or something, to reduce the drift, or (b) calculate the rotation off of a running continuous cumulative count, dividing by the appropriate integer to get the number of degrees to turn.

--
Brian Davis

Anonymous said...

What a beautiful design! Good work!

Tom Johnson said...

This is fantastic! The choice of music is especially nice.

Will George said...

I was looking at this post again (In fact several times) I think this is the MOST creative thing I have seen using LEGO and NXT!
Great work.. It is amazing!

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