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Detecting Center Goal Position - FTC 
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Post Detecting Center Goal Position - FTC
Hi, so my team is trying to figure out the best way to detect the center goal position. At our previous competition(Minnesota State) we used the Ultrasonic Sensor but found that it didn't work reliably even though it worked 100% in practice. We figured that it had to be lineup problems as the Ultrasonic could have been hitting the kickstand or something. We also tried using a IR Seeker but found we didn't get different zones even with MHTS's IR Driver. Has any team found a way to detect center goal position close to 100% reliably? Thanks!

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Sun Feb 22, 2015 6:57 pm
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Joined: Mon Dec 15, 2014 12:46 am
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Post Re: Detecting Center Goal Position - FTC
I haven't started using the IR sensor yet as the robot has been unusable for software.....but after our last competition, I learned to use the right sensor for the job, just like for hardware, using the correct tool for the job.

I was trying to use a color sensor to sense the center goal since we did not want to use the IR yet which would include the sensor MUX, more work for both hardware, electrical and software. However, now since we have time before state, we are going to try playing with the IR. I would encourage you to continue playing with the IR sensor as that is kinda the best way to get the center goal. We have 2 IR sensors, so that might help better than 1 since you can get a better range of values to compare. (I don't know how many you have)

If you still go with the Ultrasonic, or even with the IR, I would suggest having a safety path, in case the IR malfunctions or the like so that the robot can still try to score, but not necessarily in the center goal.

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Mon Feb 23, 2015 10:23 am
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Post Re: Detecting Center Goal Position - FTC
Well the problem we had is that we have 2 IR seekers yet we have same zones for 2 positions even with MHTS driver. That's the main reason we were using ultrasonic but now because of its inaccuracy at the competition we don't want to anymore. Now we are just stuck with trying to get any sensor that is accurate for it .

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Tue Feb 24, 2015 12:40 am
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Post Re: Detecting Center Goal Position - FTC
What were the readings of the two IR seekers with different center goal positions? Where did you park your robot before the match starts? We park our robot on the left side of the parking zone like this (https://www.youtube.com/watch?v=9YlX7rq9Gxg). We read both IR seekers. The left one read the same value on all 3 center goal positions but the right one gave us 7, 8 and 9 for positions 1, 2 and 3. From that, we chose one of the three paths for the 3 positions. That's very reliable.


Tue Feb 24, 2015 2:05 am
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Post Re: Detecting Center Goal Position - FTC
Well for us, we tested the IR Seeker and on the Right IR we got 9 for 2 of the positions. At the moment, I can't remember the other values but it was the same problem where 2 positions were just 1 zone. We were lining up on the far left of the parking zone. If we moved forward from our position we were able to find the position of the center goal but we weren't able to from the parking zone.

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Thu Feb 26, 2015 10:33 am
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Post Re: Detecting Center Goal Position - FTC
I can think of two ways to fix this. First, adjust the mounting angle of the right IR. Zone 9 is the wide zone, so it may enclose two center goal positions. You may be able to turn the IR seeker a little bit until one of the zones read 8 instead.
Secondly, since you said you can move forward and be able to tell them apart, then why don't you change your code such that if the IR seeker reads 9 initially, move forward 1 foot and read the IR seeker again.


Thu Feb 26, 2015 1:28 pm
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