Line Followers with Easy C

VEX V5 General Discussion Technical Discussion
1

We have been working with line followers as we believe that we will need them with this year’s game.

We find that the placement of the line followers is very important as we have experimented with several locations and configurations of the line followers without great success.

Is anyone out there willing to share the line follower secrets?

  1. How far apart should they be?
  2. Do you have them in a straight line?
  3. Do they work better in a “V” configuration with the left and right closer to the front of the robot?
  4. Do they work better in an inverted “V” configuration with the center closer to the front of the robot?
  5. If they work better in a “V” configuration what have you noticed as the best distance apart?
  6. Are you willing to share turning speeds (what have you observed to be the best speeds for changing course when the robot gets off the line)?
  7. What distance from the foam tile would you say works the best (in observation/testing the values returned vary with the distance from the tiles)?
  8. How many have you been using? 2/3/5
  9. How have you been detecting corners?

I realize this is a lot to ask but if someone is willing to share we should be appreciative. Either reply to this message or send a PM and we can talk.

Thanks in advance.

2

We recommend using the line followers in a linear pattern. I’d also recommend using the new small line followers as they have a smaller “deadzone” between the sensors. I’ve had best results when using 5 sensors together as it allows you to collect more data and address what’s happening in varying ways.

I’d also have the code ramp up the speed based on being on the center sensor. The longer it is on the middle line sensor the faster it will go. As, it starts to drift off the center sensor, have it ramp down the speed.

You can also do proportional control. Where the outside sensors add or subtract from being on the line, it’s a bit complicated as you have to set a zero value for the sensors. But it works really well, especially with five sensors.

3

Thanks for the feedback.

Quite timely as well since we will be working on line followers again this week.

We will try with 5 followers in a line and then use the suggestion of speed control based on the sensor currently “on the line.”

Quick followup - do you have suggestions for distance from the floor tile? We do see variation in the returned values based on the distance from the floor tile. Would be nice to know what distance is best if someone knows.

4

.05in-.1in is optimum. Closer is better as external light sources can’t interfere with the reading.