Thursday, a duration of 3 hours attended by the entire group.
The plan
1. The plan for today is getting Kristian and Tore up to speed, that is installing leJOS on their laptops.
2. When that works, we will proceed with last weeks lab excercises, hopefully completing those and then moving on to this weeks excercises. This means getting the car to follow the line,
3. testing the light on different colors.
4. testing different sleeptimes.
The execution of the plan
1. Just like last week, we ran into touble, this time installing eclipse plugin. Tore installed the plugin through eclipse, which didn’t work for Troels and Kristian, eclipse could not contact the plugin server. Kristian then downloaded pulse from http://www.poweredbypulse.com/download_win.php
and could install the plugin. Didn’t work for Troels.
2. That means first building the car, which actually took longer than expected. Tore then uploaded the linefollower program to the NXT and we got it to follow the edge of a white papir on a blue floor.
3. Colorvalues:
We tested the sensor in the lab with the above ambient light, about 3-4 cm above the subject. The observation is, that the percentage rises when the distance increases. Also, different colors seem to have almost the same light percentage, which makes it hard to distinguish them from one another.
| White | 54% |
| Green | 43% |
| Blue | 44% |
| Yellow | 53% |
| Red | 51% |
| Black | 35% |
To get the blackWhiteThreshold you could just take the average of the black and white percentage. In our case: (35+54)/2 = 44.5
4. Sleepcycles.
The default sleeptime is 100 ms. That is, every 100 ms the car takes measurements and adjusts its direction accordingly. If we decrease the sleeptime to, say, 50 ms, the car will take measurements more often, thus correcting the direction more often and it will oscillate faster. On the other hand, increasing the time will make it take larger turns, and decrease the cars ability to follow the line.
Status
It is a bit tiresome that we keep having trouble just installing the system, although now it works on Tore’s computer, so we might just use his for the rest of the course. Yet it was nice to finally get the robot working
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