diff --git a/docs/static/tutorials/line-following.png b/docs/static/tutorials/line-following.png new file mode 100644 index 00000000..d57a2471 Binary files /dev/null and b/docs/static/tutorials/line-following.png differ diff --git a/docs/static/tutorials/line-following/if-then-else-dropdown.png b/docs/static/tutorials/line-following/if-then-else-dropdown.png new file mode 100644 index 00000000..a25dd52e Binary files /dev/null and b/docs/static/tutorials/line-following/if-then-else-dropdown.png differ diff --git a/docs/static/tutorials/line-following/line-following.gif b/docs/static/tutorials/line-following/line-following.gif new file mode 100644 index 00000000..de56b679 Binary files /dev/null and b/docs/static/tutorials/line-following/line-following.gif differ diff --git a/docs/tutorials.md b/docs/tutorials.md index db637216..a4ecd654 100644 --- a/docs/tutorials.md +++ b/docs/tutorials.md @@ -54,5 +54,11 @@ Step by step guides to coding your @boardname@. "cardType": "tutorial", "url":"/tutorials/what-color", "imageUrl":"/static/tutorials/what-color.png" +}, { + "name": "Line Following", + "description": "Use the Color sensor to make a robot follow a line.", + "cardType": "tutorial", + "url":"/tutorials/line-following", + "imageUrl":"/static/tutorials/line-following.png" }] ``` \ No newline at end of file diff --git a/docs/tutorials/line-following.md b/docs/tutorials/line-following.md new file mode 100644 index 00000000..1c82e073 --- /dev/null +++ b/docs/tutorials/line-following.md @@ -0,0 +1,111 @@ +# Line Following + +## Introduction @fullscreen + +Make a program to follow a line using the Color sensor and reflected light. + +![Brick with color sensors tracking a yellow line](/static/tutorials/line-following/line-following.gif) + +## Step 1 + +We are going to test and see if the reflected light is white (outside the line) or black (on the line), and drive our robot accordingly. Open the ``||logic:Logic||`` Toolbox drawer. From the **Conditionals** section, drag out an ``||logic:If then else||`` block onto the Workspace, and drop it into the ``||loops:forever||`` loop. + +```blocks +forever(function () { + if (true) { +      + } else { +      + } +}) +``` + +## Step 2 + +Open the ``||logic:Logic||`` Toolbox drawer again. From the **Comparison** section, drag out ``||logic:0 < 0||`` comparison block onto the Workspace, and drop it into the ``||logic:if then else||`` block, replacing ``true``. + +```blocks +forever(function () { + if (0 < 0) { +      + } else { +      + } +}) +``` + +## Step 3 + +Open the ``||sensors:Sensors||`` Toolbox drawer. From the **Color Sensor** section, drag out a ``||sensors:color sensor light||`` value block onto the Workspace, and drop it into the first slot of the ``||logic:0 < 0||`` comparison block, replacing the `0`. + +```blocks +forever(function () { + if (sensors.color3.light(LightIntensityMode.Reflected) < 0) { +      + } else { +      + } +}) +``` + +## Step 4 + +If the value of the reflected light is greater than 40% (white or very light) then our robot is outside the line, and we should steer it to the left. In the ``||logic:0 < 0||`` comparison block, click the operator drop-down menu to change from ``<`` to ``>`` comparison, and change the compared value to `40` replacing `0`. + +![Logic operator dropdown for conditional block](/static/tutorials/line-following/if-then-else-dropdown.png) + +```blocks +forever(function () { + if (sensors.color3.light(LightIntensityMode.Reflected) > 40) { +      + } else { +      + } +}) +``` + +## Step 5 + +Open the ``||motors:Motors||`` Toolbox drawer. Drag out **2** ``||motors:tank large motors||`` blocks onto the Workspace, and drop one of them into the ``||logic:if||`` part, and the other into the ``||logic:else||`` part of the ``||logic:if then else||`` block. + +```blocks +forever(function () { + if (sensors.color3.light(LightIntensityMode.Reflected) > 40) { + motors.largeBC.tank(50, 50) + } else { + motors.largeBC.tank(50, 50) + } +}) +``` + +## Step 6 + +In the first ``||motors:tank large motors||`` block in the ``||logic:if||`` clause, change the speed values of the motors from ``50%``, ``50%`` to ``5%``, ``15%``. This slows down the robot, and steers it to the left (because the **C** motor is driving faster than the **B** motor). + +```blocks +forever(function () { + if (sensors.color3.light(LightIntensityMode.Reflected) > 40) { + motors.largeBC.tank(5, 15) + } else { + motors.largeBC.tank(50, 50) + } +}) +``` + +# Step 7 + +In the second ``||motors:tank large motors||`` block in the ``||logic:else||`` clause, change the speed values of the motors from ``50%``, ``50%`` to ``15%``, ``5%``. This slows down the robot, and steers it to the right (because the **B** motor is driving faster than the **C** motor). + +```blocks +forever(function () { + if (sensors.color3.light(LightIntensityMode.Reflected) > 40) { + motors.largeBC.tank(5, 15) + } else { + motors.largeBC.tank(15, 5) + } +}) +``` + +## Step 8 + +Now, let’s download our program to the brick. Plug your @boardname@ into the computer with the USB cable, and click the blue **Download** button in the bottom left of your screen. Follow the directions to save your program to the brick. Attach a Color Sensor to Port 3 of your brick, and attach your brick to a driving base with large motors attached to Ports B and C. See the instructions for building a _Driving Base with Color Sensor Down_. Test your program by positioning your robot to the right of a dark, thick line and then let it drive!