How do u get your robot to follow the white line??????????????????

[HuskieRobotics]

How do you program your robot to follow the white line that leads to the ball release. My team wants it as a backup in case the tracker doesn't work, but i don't have a clue how to program it... Can someone help me????please??????

[jacob_dilles]

http://www.chiefdelphi.com/forums/se...searchid=72414

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[HuskieRobotics]

i did do that none had any examples of code for the line follower, I really did not want to look through all of them but i have and still nothing can you please help me???????

[KenWittlief]

following the line would be difficult, because of the two 45° turns that it takes

your bot will end up being pretty slow if thats the way you find the release ball.

[HuskieRobotics]

I realize that but we want it only as a back up in case something screws up in the ir tracker. So can you please help me???????

[KenWittlief]

I dont have any code that you can cut and paste

but the algorythm is pretty simple if you have two sensors on your bot

you would put them on either side of the line, tell your bot to normally go straight ahead at a relatively slow speed.

then if the left sensor sees the line, turn towards the left

if the right sensor sees the line, turn towards the right

if neither sensor sees the line, go straight ahead.

you will have to test the code on your bot with the sensors and adjust how fast the bot moves forwards, and how hard it turns when it sees the line. You might also need to tell it to stop moving forward when its turning.

thats the simple version of it.

[Phil_Lutz]

Originally Posted by KenWittlief

then if the left sensor sees the line, turn towards the left
if the right sensor sees the line, turn towards the right
if neither sensor sees the line, go straight ahead.

If you mount 3 sensors it's easier.
if left only sees, moved left "harder"
if left and center sees, move left "slightly"
if center only drive straight

same on the right.

too fast...(overran the line) what was the last sensor to see the line?
If left pivot left (right forward/left backward)
and versa visa.

We are counting the times we run off the line to determine where we are.

3 hard turns to re-aquire and we are there.

Phil

[Elgin Clock]

Iww... precious time waster in that type of auto-mode.. lol

Just do like we do and dead reckon, and get to the ball in ~4.16 seconds!!

[KenWittlief]

for auton mode, we are using a yaw rate sensor to generate a compass heading, pointing the bot between the beacon and the moble goal, and using the gyro to go straight ahead

until our IR sensor sees the beacon (it has a very narrow window of view - like a pinhole camera)

then we turn hard towards the release ball, using the gyro again to measure a precise turn (ie 80° or 81 or 83...)

then moving straight ahead with our arm at release ball height, until contact swithces on the front hit the bottom railing

this should allow us to run at full speed most of the way there - we will see how it works on the real field.

[Phil_Lutz]

Originally Posted by Elgin Clock

get to the ball in ~4.16 seconds

And what does your bot do for the next 10 secs...
Dead rec back to harvest balls?

Phil
ps. We get there in 7secs with line follow and a 4fps drive train. Not much wasted time. and fully deployed to react once there

24ft / 7sec = 3.42 ft per sec not bad for a 4fps system.

[KenWittlief]

last year we used line following and had seven sensors on the bot on a bar - same idea as above, depending on which sensor sees the line you turn harder and harder

it worked ok, but we abandoned that approach and used the gyro as a compass, and started out backwards, doing a V turn

we hit the wall in 3 seconds consistantly last year.

This year our drivetrain is slower, but our navigation with the gyro should allow us to run at full speed most of the way there.

thats the trick - not outrunning your sensors

[Phil_Lutz]

Originally Posted by KenWittlief

thats the trick - not outrunning your sensors

But that is exactly what we ARE counting on
We want to overrun the line exactly 3 times (each corner) then we stop.
We (at last test) overrun the line by 6 inches before the program reacts to the change. All good.

Phil

[Elgin Clock]

Originally Posted by Phil_Lutz

And what does your bot do for the next 10 secs...
Dead rec back to harvest balls?

Maybe, but we haven't quite figured that out yet.. lol We are just glad that we got autonomous to work before we shipped this year.. The first year we did that.. Yay to us!! Now that's progress!!

One more meeting should be enough to figure out what to do in those next 10 seconds, maybe a 180 spin just for for kicks... Then again maybe not, I don't want to drive into a ball and tip over because of it getting lodged under us!
Probably more than likely nothing though, just a waiting game for the next strategical move, and time to charge up that compressor.

[Ryan M.]

Originally Posted by Phil_Lutz

If you mount 3 sensors it's easier.
if left only sees, moved left "harder"
if left and center sees, move left "slightly"
if center only drive straight

same on the right.

too fast...(overran the line) what was the last sensor to see the line?
If left pivot left (right forward/left backward)
and versa visa.

We are counting the times we run off the line to determine where we are.

3 hard turns to re-aquire and we are there.

Phil

That is basically the same as what we are doing. It works almost every time. (if you line it up horribly unstraight with the line at the start it just sits there and jerks back and forth.)

[Phil_Lutz]

Originally Posted by Texan

That is basically the same as what we are doing. It works almost every time. (if you line it up horribly unstraight with the line at the start it just sits there and jerks back and forth.)

During the scrimmage we attended one student aligned the robot at about a 45~ angle to the line. He was asked to align it he replied "It will be fine". The robot's first command turned out to be drive forward. it went off the line, spun to reaquire, crossed the line again at 90~ to the line spun hard again and crossed the line at about 45~. Total distance travelled in auto. 2 ft from the wall.


Ah youth.