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General Discussion / Re: Straights without walls
« Last post by Green on March 26, 2013, 03:53:38 PM »
for question 1: post error usually smaller than wall error even though they are at same distance. No way to distinguish them if you don't want to make your PID be complicated. The point is your mouse should be able go straight without sensor at first place(by using encoder and gyro), then add sensor error to your total error. Most of the time my mouse just ignore the post since the reflection area is smaller than a whole wall, it actually makes your mouse perform better at fishbone, but you need to make mouse go straight with sensor first.

question 2: i made offset fairly small, that's actually some threshold I use to determine if there is wall or no wall for floodfill.I use 2 Boolean to switch the status(one for left wall the other for right wall), my diagonal offset is likely 200 out of 4096 ish, since my sensor reads pretty far. You need to test out based on your own mouse
General Discussion / Straights without walls
« Last post by valar on March 05, 2013, 12:57:39 PM »
Well I have already build my first micromouse and after writing some 'easy' corrections I have a big problem now. When there's no wall on the left or right side for a longer distance my mouse crashes very often. Firstly I thought that it can be handled by front sensors. But it wasn't good solution  becouse:
  • Front sensors must by aimed a lot outside from the front wall (so it's hard to corectly detect wall in front of mouse)
  • Error must be enough big to react (which isn't good for straight of course)
Secondly I thought that we can handled it tradicionaly (like with walls) by diagonal sensors. The problem is fact that signal from post is very short and unstable and with higher speed it didn't work well.
And right now I have some idea but I don't realy know how to do that :) Well why just measure time difference between detecting posts  on left and right side? It should give us good information about angular error. The question is how to separate posts from walls ? Second qustions is about offset error (well, it's isn't so dangerouse as heading error but still it's should be posible to correct it).  Is there any better solution for correcting that ? Of course crital in this situation is turning. But it's imposible to detect idealy wall-to no-wall moment (there can be some heading or offset error) and we should be prepared for that.
Natcar / Re: what is the difference between 5 sensors and 3 sensors
« Last post by <Dr. Briggs> on December 10, 2012, 01:58:54 PM »
Hi Green,

What's the difference (advantages) of choosing 5 sensors over 3 sensors for natcar?

If you are talking about 3 front and 2 back, there MAY be an advantage because of being able to calculate directly the angle the car makes with the wire (instead of having to take the derivative). We've never tried 5 sensors in any configuration, so it's hard to say definitively.

I do know this: the Automated Highway System Demo '97 with 8 Buick LeSabres in a platoon on the I-15 freeway in San Diego had 6 magnetic sensors, 3 front and 3 rear, and they were perfectly reliable and effective. I have a vid of that if you want to see it.

Also, a camera looking 1 foot ahead plus 3 magnetic sensors just forward of the front wheels offers the same possible advantage as the front/rear sensor layout.
Natcar / Re: what is the difference between 5 sensors and 3 sensors
« Last post by Green on December 09, 2012, 04:18:49 PM »
There is no such advantage or disadvantage between 5 sensors and 3 sensors. It's most likely different people's preference. Typically, 3 sensors will make the car work good enough as long as the inductor you choose will have signal overlap to each other.
Natcar / what is the difference between 5 sensors and 3 sensors
« Last post by Hui Wang on December 09, 2012, 02:46:36 PM »
Hi Green,

What's the difference (advantages) of choosing 5 sensors over 3 sensors for natcar?
Natcar / First Post here, Feel free to ask and answer questions here.
« Last post by Green on December 08, 2012, 09:54:33 PM »
hello, fellows.
    I'd expect all your problems will be solved within 24 hours, enjoy and have fun.
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