Stop the robot after the third line - Revision history

Mol: Marked this version for translation

2020-09-15T17:11:10Z

Marked this version for translation

← Older revision		Revision as of 20:11, 15 September 2020
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	=== Introduction ===		=== Introduction === <!--T:1-->

			<!--T:2-->
	How to stop the robot after passing the third (or ''n''th) line? This problem is very often encountered in FIRST Lego League (FLL) or in Rescue competitions. The problem is that the sensor reads continuous data, and the simplest solutions wont work.		How to stop the robot after passing the third (or ''n''th) line? This problem is very often encountered in FIRST Lego League (FLL) or in Rescue competitions. The problem is that the sensor reads continuous data, and the simplest solutions wont work.

			<!--T:3-->
	[[File:StopAt3rdLine.png\|thumb]]		[[File:StopAt3rdLine.png\|thumb]]

			<!--T:4-->
	This page gives two different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines. The flip flop is a robust method which works with a variable width lines.		This page gives two different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines. The flip flop is a robust method which works with a variable width lines.


	=== Robot ===		=== Robot === <!--T:5-->

			<!--T:6-->
	Almost any robot will do. We use Asimov 2/ Verne robot.		Almost any robot will do. We use Asimov 2/ Verne robot.

	=== Sensors ===		=== Sensors === <!--T:7-->

			<!--T:8-->
	One color sensor is needed.		One color sensor is needed.

	=== Example Videos ===		=== Example Videos === <!--T:9-->

			<!--T:10-->
	The video is about the second method, only.		The video is about the second method, only.

			<!--T:11-->
	<youtube>hHpo12qUhgc</youtube>		<youtube>hHpo12qUhgc</youtube>

	=== Theory ===		=== Theory === <!--T:12-->

			<!--T:13-->
	The two different methods are described below. The color sensor reads the reflected light intensity continuously, but the reading frequency is rather large. Thus, during passing the black line, the sensor reads hundreds of close to zero, or black, values. See, the image.		The two different methods are described below. The color sensor reads the reflected light intensity continuously, but the reading frequency is rather large. Thus, during passing the black line, the sensor reads hundreds of close to zero, or black, values. See, the image.

			<!--T:14-->
	[[File:StopAt3rdLineSensor.png\|thumb\|Sensor readings while the robot passes black lines.]]		[[File:StopAt3rdLineSensor.png\|thumb\|Sensor readings while the robot passes black lines.]]

			<!--T:15-->
	The calibrated color sensor reads about 100 at white, and while passing the black line the sensor values are about 0.		The calibrated color sensor reads about 100 at white, and while passing the black line the sensor values are about 0.

	==== Using the timer/ rotation angle ====		==== Using the timer/ rotation angle ==== <!--T:16-->

			<!--T:17-->
	By using the timer we can drive past the black line, and again look for the next black line. After finding the third one, we stop. This can be done in a loop, also. Usually, if you need to repeat the code, use a loop instead of copying the same script again.		By using the timer we can drive past the black line, and again look for the next black line. After finding the third one, we stop. This can be done in a loop, also. Usually, if you need to repeat the code, use a loop instead of copying the same script again.


	==== Using flip flop circuit ====		==== Using flip flop circuit ==== <!--T:18-->

			<!--T:19-->
	The idea of the flip flop is that first we flip the state to black, and then after finding white we flop the state back to white. Note that the sensor continuously measures the reflectance.		The idea of the flip flop is that first we flip the state to black, and then after finding white we flop the state back to white. Note that the sensor continuously measures the reflectance.


	=== Example Code ===		=== Example Code === <!--T:20-->

			<!--T:21-->
	The example codes with two different algorithms are shown.		The example codes with two different algorithms are shown.

	==== Using the timer ====		==== Using the timer ==== <!--T:22-->

			<!--T:23-->
	The timer based code is rather reliable and works perfectly even on difficult environments. The timer can be replaced by the rotation angle.		The timer based code is rather reliable and works perfectly even on difficult environments. The timer can be replaced by the rotation angle.

			<!--T:24-->
	[[File:Stop3rline I.png\|thumb\|The timer code.]]		[[File:Stop3rline I.png\|thumb\|The timer code.]]

	==== Using the flip flop algorithm ====		==== Using the flip flop algorithm ==== <!--T:25-->

			<!--T:26-->
	The flip flop algorithm is simple and reliable, if the ground floor is easy enough.		The flip flop algorithm is simple and reliable, if the ground floor is easy enough.

			<!--T:27-->
	[[File:Fliflop stop3rdLine.png\|thumb\|The flip flop algorithm is easy to implement.]]		[[File:Fliflop stop3rdLine.png\|thumb\|The flip flop algorithm is easy to implement.]]

	=== Exercises ===		=== Exercises === <!--T:28-->

			<!--T:29-->
	* How fast can you make the robot to pass exactly three lines? Measure the time, and the extra passage (slippage), which the root makes after passing the last line.		* How fast can you make the robot to pass exactly three lines? Measure the time, and the extra passage (slippage), which the root makes after passing the last line.
	* Make the robot work with two sensors, and assign other sensor to follow a line, and the other to stop after to stop the robot after 3rd line. See the image.		* Make the robot work with two sensors, and assign other sensor to follow a line, and the other to stop after to stop the robot after 3rd line. See the image.
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			<!--T:30-->
	This course is supported by [https://meet-and-code.org/ Meet and Code]. The course is made in collaboration with [http://www.fllsuomi.org/ Robotiikka- ja tiedekasvatus ry].		This course is supported by [https://meet-and-code.org/ Meet and Code]. The course is made in collaboration with [http://www.fllsuomi.org/ Robotiikka- ja tiedekasvatus ry].
	[[File:MeetAndcodeLogo.png\|thumb]]		[[File:MeetAndcodeLogo.png\|thumb]]

			<!--T:31-->
	[[Meet and Code 2020 I: Ev3-G\| Back to Meet and Code 2020 I: Ev3-G front page]]		[[Meet and Code 2020 I: Ev3-G\| Back to Meet and Code 2020 I: Ev3-G front page]]

	</translate>		</translate>

Mol at 17:05, 15 September 2020

2020-09-15T17:05:54Z

← Older revision		Revision as of 20:05, 15 September 2020
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			<languages/>
			<translate>

	=== Introduction ===		=== Introduction ===

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	[[Meet and Code 2020 I: Ev3-G\| Back to Meet and Code 2020 I: Ev3-G front page]]		[[Meet and Code 2020 I: Ev3-G\| Back to Meet and Code 2020 I: Ev3-G front page]]

			</translate>

Mol at 17:05, 15 September 2020

2020-09-15T17:05:06Z

Mol: /* Example Videos */

2020-09-14T18:14:18Z

Example Videos

← Older revision		Revision as of 21:14, 14 September 2020
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	=== Example Videos ===		=== Example Videos ===

			The video is about the second method, only.

	<youtube>hHpo12qUhgc</youtube>		<youtube>hHpo12qUhgc</youtube>

Mol: /* Example Videos */

2020-09-14T18:10:16Z

Example Videos

← Older revision		Revision as of 21:10, 14 September 2020
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	=== Example Videos ===		=== Example Videos ===

			<youtube>hHpo12qUhgc</youtube>

	=== Theory ===		=== Theory ===

Mol: /* Example Code */

2020-09-12T09:57:54Z

Example Code

← Older revision		Revision as of 12:57, 12 September 2020
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	=== Example Code ===		=== Example Code ===

			The example codes with two different algorithms are shown.

	==== Using the timer ====		==== Using the timer ====

Mol: /* Using the timer */

2020-09-12T09:53:37Z

Using the timer

← Older revision		Revision as of 12:53, 12 September 2020
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	==== Using the timer ====		==== Using the timer ====

			The timer based code is rather reliable and works perfectly even on difficult environments. The timer can be changed to rotation angle.

			[[File:Stop3rline I.png\|thumb\|The timer code.]]

	==== Using the flip flop algorithm ====		==== Using the flip flop algorithm ====

Mol: /* Using the flip flop algorithm */

2020-09-12T09:45:46Z

Using the flip flop algorithm

← Older revision		Revision as of 12:45, 12 September 2020
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	==== Using the flip flop algorithm ====		==== Using the flip flop algorithm ====

			The flip flop algorithm is simple and reliable, if the ground floor is easy enough.

	[[File:Fliflop stop3rdLine.png\|thumb\|The flip flop algorithm is easy to implement.]]		[[File:Fliflop stop3rdLine.png\|thumb\|The flip flop algorithm is easy to implement.]]

Mol at 09:37, 12 September 2020

2020-09-12T09:37:04Z

← Older revision		Revision as of 12:37, 12 September 2020
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	[[File:StopAt3rdLine.png\|thumb]]		[[File:StopAt3rdLine.png\|thumb]]

	This page gives to different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines.		This page gives to different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines. The flip flop is a robust method which works with a variable width lines.


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	=== Theory ===		=== Theory ===

	~~==== Readings~~ of the ~~color sensor ====~~		The two different methods are described below. The color sensor reads the reflected light intensity continuously, and the reading frequency is big. Thus, during passing the black line, the sensor reads perhaps hundreds of close to zero values. See, the image.

	[[File:StopAt3rdLineSensor.png\|thumb]]		[[File:StopAt3rdLineSensor.png\|thumb\|Sensor readings while the robot passes black lines.]]

	The calibrated color sensor reads about 100 at white, and while passing the black line it reads about 0.		The calibrated color sensor reads about 100 at white, and while passing the black line it reads about 0.
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	==== Using flip flop circuit ====		==== Using flip flop circuit ====

			The idea of the flip flop is that first we flip the state to black, and then after finding white we flop the state back to white. The sensor continuously measures the reflectance, and


	=== Example Code ===		=== Example Code ===
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	==== Using flip flop ~~circuit~~ ====		==== Using the flip flop algorithm ====

			[[File:Fliflop stop3rdLine.png\|thumb\|The flip flop algorithm is easy to implement.]]

	=== Exercises ===		=== Exercises ===

			* How fast can you make the robot to pass exactly three lines? Measure the time, and the extra passage (slippage), which the root makes after passing the last line.
			* Make the robot work with two sensors, and assign other sensor to follow a line, and the other to stop after to stop the robot after 3rd line. See the image.
			*
			*

	This course is supported by [https://meet-and-code.org/ Meet and Code]. The course is made in collaboration with [http://www.fllsuomi.org/ Robotiikka- ja tiedekasvatus ry].		This course is supported by [https://meet-and-code.org/ Meet and Code]. The course is made in collaboration with [http://www.fllsuomi.org/ Robotiikka- ja tiedekasvatus ry].

Mol at 19:43, 5 September 2020

2020-09-05T19:43:25Z

← Older revision		Revision as of 22:43, 5 September 2020
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	[[File:StopAt3rdLine.png\|thumb]]		[[File:StopAt3rdLine.png\|thumb]]

	This page gives to different solutions: (i) using timer to pass the lines and (ii) using flip-flop algorithm to count the black lines.		This page gives to different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines.


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	[[File:StopAt3rdLineSensor.png\|thumb]]		[[File:StopAt3rdLineSensor.png\|thumb]]

			The calibrated color sensor reads about 100 at white, and while passing the black line it reads about 0.

	==== Using the timer ====		==== Using the timer/ rotation angle ====

			By using the timer we can drive past the black line, and again look for the next black line. After finding the third one, we stop. This can be done in a loop, also. Usually, if you need to repeat the code, use a loop.