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--- wiki:v2:lego_line_following_demo [2019/01/31 00:42]
pixycam
+++ wiki:v2:lego_line_following_demo [2019/01/31 01:43] (current)
pixycam
@@ Line 17: / Line 17: @@
   - Attach Pixy2 and plug into port 1 as shown.  Note how Pixy2 is pointed down (It's going to be tracking lines on the ground!)\\
 {{wiki:v1:img_5351_result.jpg?400}}
+  - Here's what the finished robot should look like. Note the angle that Pixy2 is looking at the ground.\\
+{{wiki:v1:img_5345_result.jpg?400}}
 ==== Cables (IMPORTANT!) ====
@@ Line 31: / Line 32: @@
 {{wiki:img:3e3b64f2ff052ac58280fa2315eff9d803714e6e.png}}\\
-  - Browse to the location where you unzipped the "LEGO blocks and examples" file (which you can download [[https://pixycam.com/downloads-pixy2/|on this page]]), and then to the **examples** directory and select "line\_follow.ev3" and click on **Open**.
+  - Browse to the location where you unzipped the "LEGO blocks and examples" file (which you can download [[https://pixycam.com/downloads-pixy2/|on this page]]), and then to the **examples** directory and select "line\_follow.ev3" and click on **Open**. You should see a program that looks like this (below).\\
-  - Click on the "track" tab. You should see a program that looks like this (below).\\
+{{wiki:v1:image_741.png}}\\
-{{}}\\
+  - Draw a smooth line on a large sheet of paper using a black marker.  Taping several standard-sized pieces of paper together to create a larger sheet of paper is a good approach.  You can make a circle, oval, figure-eight, or something more complex, but keeping it simple is good for the first test.
-  - Draw a smooth line on a large sheet of paper using a black marker.  Taping several standard-sized pieces of paper together to create a larger sheet of paper is a good approach.  You can make a circle, oval, figure-eight, or something more complex, but keeping it simple is good for the first test.
   - Place your robot on the line that you've drawn and clicking on the play icon in the lower right corner of your EV3 software window.\\
 {{wiki:img:aa5d26848e8509a94a41c8bc66ed36125ee5af36.png}}\\
@@ Line 43: / Line 43: @@
 ===== Troubleshooting =====
-  - If your robot turns away from your object, make sure that the motor cables aren't crossed.  That is, if you are facing the motor ports (the back of the robot), the left motor connects to port B, the right motor connects to port A.
+  - If your robot turns away from the line, make sure that the motor cables aren't crossed.  That is, if you are facing the motor ports (the back of the robot), the left motor connects to port B, the right motor connects to port A.
-  - If your robot doesn't follow the line closely, try tilting Pixy2 more downward toward the paper.
+  - If your robot starts turning left before the line curves to the left (for example), try tilting Pixy2 more downward toward the paper.  That is, if Pixy2 is tilted too far up, it will see too much of the line in front of it and "anticipate" any turns.  On the other hand, this might be what you want. :)
-  - Although it's unlikely, sometimes the Vector can become "inverted "such that the Vector points down instead of up, which will cause your robot to back-up (reverse) instead of move forward.  It will resolve itself because your robot will back-up and turn around such that the Vector is pointing up again, but it can be unexpected.  The easiest way to prevent the Vector from being is to place a blank sheet of paper in front of Pixy2 such that it loses the current Vector, then remove the paper before you start the program.  After you remove the paper, Pixy2 will see the line in front of it, assign it as the Vector, and (by default) choose an upward orientation.  Your robot will then move forward.
+  - Although it's unlikely, sometimes the Vector can become "inverted" such that the Vector points down instead of up, which will cause your robot to back-up (reverse) instead of move forward.  It will resolve itself because your robot will back-up and turn around such that the Vector is pointing up again, but it can be unexpected.  The easiest way to prevent this is to place a blank sheet of paper in front of Pixy2 such that it loses the current Vector, then remove the paper before you start the program.  After you remove the paper, Pixy2 will see the line in front of it, assign it as the Vector, and (by default) choose an upward orientation.  Your robot will then move forward.
-===== Making Turns =====
+===== Making Turns at Intersections =====
 If your line drawing has an intersection, you can tell your robot always turn left or always turn right (for example) by "hard-coding" the Turn Angle.  With the program stopped, try setting the Turn Angle to -90 degrees.
@@ Line 65: / Line 65: @@
-===== What's Next =====
+===== What's Next? =====
 Can you extend this demo to make turns based on barcodes?  Barcode images (including roadsigns!) are available [[https://pixycam.com/downloads-pixy2/|here]].

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