http://www.education.rec.ri.cmu.edu/previews/nxt_products/robotics_eng_vol_1/preview/content/projects/hallbot/forward/wheeldist/index.htm

This is the page I found to teach my kids about wheel circumference and distance.
 (Hint: the large 8.2 cm wheel has a 10" circumference so your rotation equation will be 1" distance=.1 rotation :) Super handy when quickly adjusting the robot's distance during meetings.)
This is where the lego robotics start to positively impact all other areas of learning.   I would not skip this lesson with my kids for another week of practice.  It brings math concepts to life and gives them useful, real life applications.  Now, it does seem a little advanced for 4th and sometimes 5th graders, but I am working with 4th-9th graders, and the kid's comprehension had to do with their math logic skills not their grade level, so don't shy away just because you're the first one to introduce this concept or because they are young.
Good luck,
Brandy


From: sridhar kowdley <[log in to unmask]>
To: [log in to unmask]
Sent: Sat, October 9, 2010 10:28:13 AM
Subject: Re: [VADCFLL-L] using sensors

Anothe note--
 
Please do look at the wheels-- i think some of them have measurements in cm or mm I think.  You can translate this directly to rotation and convert it to distance. 
 
Time is also a problem if you vary the power.
 
Hope that helps.
Sridhar

On Sat, Oct 9, 2010 at 7:18 AM, Lloyd O'Hara <[log in to unmask]> wrote:
Cool idea, I like it and may borrow in the future.

----- Original Message ----- From: "Eric Palmer" <[log in to unmask]> Sent: Saturday, October 09, 2010 7:07 AM

Subject: Re: [VADCFLL-L] using sensors


Also our team constructs a measuring gauge with a wheel/tire the same
size of the one on your robot. They put one of those orange pointers
on an axle and use some beams to make a handle. They then just set it
down with the point in a know position and then push it and count
rotations.  360 degrees = 1 rotation.

This way they don't have to guess, program, download, run and rinse
repeat so often.

It saves time.

On Sat, Oct 9, 2010 at 6:30 AM, Lloyd O'Hara <[log in to unmask]> wrote:
Heather,

One thing for your team to lookout for is battry charge. When the battery
charge lowers, it may take more time (seconds) to travel the same amount of
distance as it did when the battery was fully charged. (see Curt's handrill
analogy in a recent email).

Our team generally uses degrees (1/360 of the circumference of the wheels
you are using). Degrees, as well as other sensors, can be easily measured
using the "View" function on the NXT.

Lloyd


----- Original Message ----- From: "Heather Houlden" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, October 08, 2010 10:05 PM
Subject: Re: [VADCFLL-L] using sensors


It is my first year as well, so we are learning too. However, my kids are
measuring the distances the robot needs to travel.
We programmed the robot to travel in a straight line for a set time (I
think it was 10 sec). Then they measured the distance travelled, and I
had them compute the seconds per inch travelled.

Then they just multiply the seconds/inch by the number of inches the
robot needs to move, so that they can program the number of seconds
to move.
So far it seems to be working OK for them. There may be an easier way
to do it, but this is what they came up with.
Hope this helps!
Heather
Team Blockbusters

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