Follow a line - Revision history

Mol: Marked this version for translation

2020-09-14T19:21:21Z

Marked this version for translation

← Older revision		Revision as of 22:21, 14 September 2020
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	=== Introduction ===		=== Introduction === <!--T:1-->

			<!--T:2-->
	There a multiple different methods (algorithms) to follow a line. We show two simplest methods (which can be coded with a huge variety), also [[Viivanseuraaja zigzag ev3-g \|''zig zag'' linefollower]] and [[Viivanseuraaja verrannollinen ev3-g \|		There a multiple different methods (algorithms) to follow a line. We show two simplest methods (which can be coded with a huge variety), also [[Viivanseuraaja zigzag ev3-g \|''zig zag'' linefollower]] and [[Viivanseuraaja verrannollinen ev3-g \|
	proportional line follower]]. See the linked pages for more references. The line can be drawn on a huge paper, or made by using black (or colored) tape. The easiest line is smooth, but it might contain very sharp turns. However, the line should not cut itself.		proportional line follower]]. See the linked pages for more references. The line can be drawn on a huge paper, or made by using black (or colored) tape. The easiest line is smooth, but it might contain very sharp turns. However, the line should not cut itself.

	=== Robot ===		=== Robot === <!--T:3-->

			<!--T:4-->
	Any robot (with tires or treads, perhaps walking robots too) will work.		Any robot (with tires or treads, perhaps walking robots too) will work.

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

			<!--T:6-->
	One light sensor or color sensor is needed.		One light sensor or color sensor is needed.
	Some of the exercises requires two sensors.		Some of the exercises requires two sensors.

	=== Example Videos ===		=== Example Videos === <!--T:7-->

			<!--T:8-->
	<youtube>DN2prlLoyPo</youtube>		<youtube>DN2prlLoyPo</youtube>

			<!--T:9-->
	<youtube>kVce9k_e6OI</youtube>		<youtube>kVce9k_e6OI</youtube>

	=== Theory ===		=== Theory === <!--T:10-->

			<!--T:11-->
	These algorithms follow the border of the line, not the line.		These algorithms follow the border of the line, not the line.

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

			<!--T:13-->
	The color sensor should be calibrated, either in the program using black and light reflectances, or by calibrating the values from the sensor. See the linked page for more information.		The color sensor should be calibrated, either in the program using black and light reflectances, or by calibrating the values from the sensor. See the linked page for more information.

	==== Zig Zag ====		==== Zig Zag ==== <!--T:14-->

			<!--T:15-->
	''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.		''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.

			<!--T:16-->
	[[File:Zigzag.png\|thumb\|''The Zig Zag'' algorithm.]]		[[File:Zigzag.png\|thumb\|''The Zig Zag'' algorithm.]]

	==== Proportional ====		==== Proportional ==== <!--T:17-->

			<!--T:18-->
	[[File:LinefollowerProp.png\|thumb]]		[[File:LinefollowerProp.png\|thumb]]

			<!--T:19-->
	The proportional line follower steers according to the value read from the color sensor. The sensor is assumed to be calibrated, so that at value <math>c=50</math> the robot will go straight. Define a steering function		The proportional line follower steers according to the value read from the color sensor. The sensor is assumed to be calibrated, so that at value <math>c=50</math> the robot will go straight. Define a steering function

			<!--T:20-->
	<math>s(c) = 2c - 100</math>.		<math>s(c) = 2c - 100</math>.

			<!--T:21-->
	It is clearly seen, that		It is clearly seen, that
	{\| class="sortable"		{\| class="sortable"
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	The coefficient is <math>2</math> which makes the robot steer rapidly. You might wish to have smaller or larger steering effect depending on the path. The steering function can be generalized easily to		The coefficient is <math>2</math> which makes the robot steer rapidly. You might wish to have smaller or larger steering effect depending on the path. The steering function can be generalized easily to

			<!--T:22-->
	<math>s(c) = k(c-50)</math>		<math>s(c) = k(c-50)</math>

			<!--T:23-->
	which allows to test different steering coefficients <math>k</math>. This is easy to implement in Ev3-G programming language.		which allows to test different steering coefficients <math>k</math>. This is easy to implement in Ev3-G programming language.


	=== Example Code ===		=== Example Code === <!--T:24-->


	==== Zig Zag ====		==== Zig Zag ==== <!--T:25-->

			<!--T:26-->
	Zig Zag never drives straight. Either it turns to left or right. However, it can be made very fast, and reliable---of course depending on the line. The turning part is coded into ''if else'' block which is in the loop.		Zig Zag never drives straight. Either it turns to left or right. However, it can be made very fast, and reliable---of course depending on the line. The turning part is coded into ''if else'' block which is in the loop.

			<!--T:27-->
	[[File:Zigzag.png\|thumb\|Zigzag algorithm]]		[[File:Zigzag.png\|thumb\|Zigzag algorithm]]

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

			<!--T:29-->
	The proportional code reads the reflected light intensity, and if it exactly 50 the robot drives forward. Otherwise it turns to left or right. There is a proportional constant <math>c</math> to determine the speed of the turn.		The proportional code reads the reflected light intensity, and if it exactly 50 the robot drives forward. Otherwise it turns to left or right. There is a proportional constant <math>c</math> to determine the speed of the turn.

			<!--T:30-->
	[[File:Proportional.png\|thumb\|The proportional Line Follower code. The code is much shorter and perhaps easier to understand, if the maths can be understood.]]		[[File:Proportional.png\|thumb\|The proportional Line Follower code. The code is much shorter and perhaps easier to understand, if the maths can be understood.]]

	=== Exercises ===		=== Exercises === <!--T:31-->

			<!--T:32-->
	* Use the other side of the line to follow the line		* Use the other side of the line to follow the line
	* Make the robot to change the side of the line during the line following: Thus, after following the line e.g. 2 wheel rotations, use the other side of the line		* Make the robot to change the side of the line during the line following: Thus, after following the line e.g. 2 wheel rotations, use the other side of the line
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			<!--T:33-->
	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]]

Mol: /* Proportional */

2020-09-12T09:12:32Z

Proportional

← Older revision		Revision as of 12:12, 12 September 2020
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	The proportional code reads the reflected light intensity, and if it exactly 50 the robot drives forward. Otherwise it turns to left or right. There is a proportional constant <math>c</math> to determine the speed of the turn.		The proportional code reads the reflected light intensity, and if it exactly 50 the robot drives forward. Otherwise it turns to left or right. There is a proportional constant <math>c</math> to determine the speed of the turn.

	[[File:Proportional.png\|thumb]]		[[File:Proportional.png\|thumb\|The proportional Line Follower code. The code is much shorter and perhaps easier to understand, if the maths can be understood.]]

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

Mol: /* Proportional */

2020-09-12T09:10:54Z

Proportional

← Older revision		Revision as of 12:10, 12 September 2020
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	==== Proportional ====		==== Proportional ====

			The proportional code reads the reflected light intensity, and if it exactly 50 the robot drives forward. Otherwise it turns to left or right. There is a proportional constant <math>c</math> to determine the speed of the turn.

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

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

Mol: /* Zig Zag */

2020-09-12T09:04:50Z

Zig Zag

← Older revision		Revision as of 12:04, 12 September 2020
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	''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.		''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.

	[[File:Zigzag.png\|thumb~~\|left~~\|''The Zig Zag'' algorithm.]]		[[File:Zigzag.png\|thumb\|''The Zig Zag'' algorithm.]]

	==== Proportional ====		==== Proportional ====

Mol: /* Zig Zag */

2020-09-12T09:04:29Z

Zig Zag

← Older revision		Revision as of 12:04, 12 September 2020
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	''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.		''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.

	[[File:Zigzag.png\|thumb\|''The Zig Zag'' algorithm.]]		[[File:Zigzag.png\|thumb\|left\|''The Zig Zag'' algorithm.]]

	==== Proportional ====		==== Proportional ====

Mol: /* Zig Zag */

2020-09-12T09:04:03Z

Zig Zag

← Older revision		Revision as of 12:04, 12 September 2020
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	==== Zig Zag ====		==== Zig Zag ====

	''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.		''Zig zag'' algorithm turns to right if sees white, and to left if the sensor is on the black. Or vice versa. The algorithm is easy to program using only one if block. The speed and turning value need to be considered and adjusted.

			[[File:Zigzag.png\|thumb\|''The Zig Zag'' algorithm.]]

	==== Proportional ====		==== Proportional ====

Mol: /* Example Videos */

2020-09-07T20:47:29Z

Example Videos

← Older revision		Revision as of 23:47, 7 September 2020
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	<youtube>DN2prlLoyPo</youtube>		<youtube>DN2prlLoyPo</youtube>

			<youtube>kVce9k_e6OI</youtube>

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

Mol: /* Zig Zag */

2020-09-06T20:18:00Z

Zig Zag

← Older revision		Revision as of 23:18, 6 September 2020
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	Zig Zag never drives straight. Either it turns to left or right. However, it can be made very fast, and reliable---of course depending on the line. The turning part is coded into ''if else'' block which is in the loop.		Zig Zag never drives straight. Either it turns to left or right. However, it can be made very fast, and reliable---of course depending on the line. The turning part is coded into ''if else'' block which is in the loop.

	[[File:Zigzag.png\|thumb]]		[[File:Zigzag.png\|thumb\|Zigzag algorithm]]

	==== Proportional ====		==== Proportional ====

Mol: /* Example Videos */

2020-09-06T20:17:19Z

Example Videos

← Older revision		Revision as of 23:17, 6 September 2020
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	=== Example Videos ===		=== Example Videos ===

			<youtube>DN2prlLoyPo</youtube>

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

Mol: /* Sensors */

2020-09-06T20:15:51Z

Sensors

← Older revision		Revision as of 23:15, 6 September 2020
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	=== Sensors ===		=== Sensors ===

	One light sensor or color sensor is needed.		One light sensor or color sensor is needed.
			Some of the exercises requires two sensors.

	=== Example Videos ===		=== Example Videos ===