Easiest way to make a Simple Line Follower robot

a machine that follows a line, either a black line on white surface or vise-versa. For Beginners it is usually their first robot to play with. In this tutorial, we will teach you to make the line follower robot move on the line with a type of feedback mechanism. It’s the most basic example of adding small intelligence to a robot, but it’s actually the designer’s intelligence!! <br /><div style="margin-bottom: 0cm;">After reading this section completely you will be playing with the one shown below. Moreover we will make it modular so that it can be easily modified in future.</div><div style="margin-bottom: 0cm;">The main electronics/mechanical components that will be used in making this line follower robot are two sensors made using LDRs, transistors as motor driver circuit, acrylic sheet, General purpose board, Two DC motors and battery.<br /><iframe allowfullscreen="" frameborder="0" height="360" src="http://www.youtube.com/embed/o5qvvWnSbkE?feature=player_embedded" width="640"></iframe>So let’s start making its chassis.</div><h2 style="margin-bottom: 0cm;"><a href="https://www.blogger.com/null" name="chassis"></a>Chassis</h2>It’s basically the frame of the robot on which motors and wheels are mounted and all the circuitry part is also placed on it.<br />For base, we will be using Acrylic sheet of dimension 14x13cm square and thickness of 4mm for our chassis, it can be easily available at any picture frame shop.<br /><div class="img_caption none" style="float: none; width: 200px;"><br /><div class="img_caption"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><img class="rg_i" data-src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT4FDjydfLYstRIrdQtbGZyJTRCHJiVcUj8jVMT87cTqkrZCJPHgQ" data-sz="f" name="WdKQiqoF6WWLOM:" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT4FDjydfLYstRIrdQtbGZyJTRCHJiVcUj8jVMT87cTqkrZCJPHgQ" style="height: 183px; margin-left: auto; margin-right: auto; margin-top: 0px; width: 229px;" /></td></tr><tr><td class="tr-caption" style="text-align: center;">Acrylic sheet</td><td class="tr-caption" style="text-align: center;"><br /></td><td class="tr-caption" style="text-align: center;"><br /></td></tr></tbody></table></div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_dsc_0262.jpg" rel="prettyPhoto[page]" target="_blank" title="Acrylic sheet"></a></div>  <br /><h2>Drive Mechanism</h2>We will be using a three wheel differential drive using two motors and one caster wheel or an Omni directional wheel. The Direction and speed of the two motors can be controlled independently. <br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Motor, Motor clamp and tyre" border="0" class="caption multithumb" height="147" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_dsc_0267.jpg" title="Motor, Motor clamp and tyre" width="200" /><br /><div class="img_caption">Motor, Motor clamp and tyre</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_dsc_0267.jpg" rel="prettyPhoto[page]" target="_blank" title="Motor, Motor clamp and tyre"></a></div><div class="img_caption none" style="float: none; width: 200px;"><img alt="Caster wheel" border="0" class="caption multithumb" height="140" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_dsc_0270.jpg" title="Caster wheel" width="200" /><br /><div class="img_caption">Caster wheel</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_dsc_0270.jpg" rel="prettyPhoto[page]" target="_blank" title="Caster wheel"></a></div><div class="img_caption none" style="float: none; width: 200px;"><img alt="Chassis Layout" border="0" class="caption multithumb" height="110" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_chasis_diagram.jpg" title="chassis Layout" width="200" /><br /><div class="img_caption">chassis Layout</div><a href="http://playwithrobots.com/images/chasis%20diagram.jpg" rel="prettyPhoto[page]" target="_blank" title="chassis Layout"></a></div>Our first step would be drilling holes to fix caster and clamps for motors. Though i haven't done any drilling while making this line following robot, just pasted caster and motor clamps with the help of double sided tape!!. But if you are making it for any small college project or competition fix every thing properly with screws. Also solder a 2 pin connector to the motors pins.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Motors with connector" border="0" class="caption multithumb" height="104" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_dsc_0274.jpg" title="Motors with connector" width="200" /><br /><div class="img_caption">Motors with connector</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_dsc_0274.jpg" rel="prettyPhoto[page]" target="_blank" title="Motors with connector"></a></div><br />Now fix motors, caster and also attach wheels to the motors. As I said it is to made modular, attach a two pin connector to each motor.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Final chassis" border="0" class="caption multithumb" height="141" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_dsc_0278.jpg" title="Final chassis" width="200" /><br /><div class="img_caption">Final chassis</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_dsc_0278.jpg" rel="prettyPhoto[page]" target="_blank" title="Final chassis"></a></div><br />Now the chassis is complete. Lets make its circuit!.<br /><h2>Circuit</h2>We will be using light sensors, particularly Light dependent Resistors (LDRs) to detect black line on white surface. The figure below will explain how to detect black line on white surface.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Line detection logic" border="0" class="caption multithumb" height="86" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_principle.jpg" title="Line detection logic" width="200" /><br /><div class="img_caption">Line detection logic</div><a href="http://playwithrobots.com/images/principle.jpg" rel="prettyPhoto[page]" target="_blank" title="Line detection logic"></a></div><br />The overall circuit for this robot is shown below.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Complete circuit" border="0" class="caption multithumb" height="115" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_lfr-without_mcu_complete.jpg" title="Complete circuit" width="200" /><br /><div class="img_caption">Complete circuit</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_lfr-without_mcu_complete.jpg" rel="prettyPhoto[page]" target="_blank" title="Complete circuit"></a></div><h2>How would the above circuit works?</h2>The logic is simple. Left sensor will be controlling left motor, when the sensor is on white surface motor will be switched on else switched off. Similarly right motor is controlled by right sensor. The picture below will give you an idea.<br /><br /><br /><img alt="logic" border="0" class="caption multithumb" height="200" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_lfr-logic.jpg" title="logic" width="161" /><br /><br /><h2><span style="font-size: large;">Now lets make it. </span></h2><br />To sense the line properly sensors must be placed on the robot is such a way that they are very close to the ground. For this we have divided the circuit into two parts, first part would be LDR and LED pairs. These are to be soldered on a small general purpose board and mounted just in front of caster wheel facing downwards. This circuit is connected to the second part with the help of a 4 pin connector. This sensor part is modular as we can use them for another purpose also. You don't need to solder them again, just unplug the connector and use them. Ensure that distance between two LDR must be 4-5mm greater than the width of the black line. It is necessary to cover the LED LDR pair with some absorbing material in order to avoid ambient light (enviremnet light) to fall on LDR. See the pictures below.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="General Purpose board" border="0" class="caption multithumb" height="118" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_general_purpose_board.jpg" title="General purpose board" width="200" /><br /><div class="img_caption">General purpose board</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_general_purpose_board.jpg" rel="prettyPhoto[page]" target="_blank" title="General purpose board"></a></div><div class="img_caption none" style="float: none; width: 200px;"><img alt="sensor Part soldered" border="0" class="caption multithumb" height="132" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_sensor_ckt.jpg" title="Sensor Part soldered" width="200" /><br /><div class="img_caption">Sensor Part soldered</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_sensor_ckt.jpg" rel="prettyPhoto[page]" target="_blank" title="Sensor Part soldered"></a></div><br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Insulate soldered part" border="0" class="caption multithumb" height="163" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_covered_sensor.jpg" title="Insulate soldered part" width="200" /><br /><div class="img_caption">Insulate soldered part</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_covered_sensor.jpg" rel="prettyPhoto[page]" target="_blank" title="Insulate soldered part"></a></div><div class="img_caption none" style="float: none; width: 200px;"><img alt="Sensor covering" border="0" class="caption multithumb" height="78" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_sensor_covering.jpg" title="sensor covering" width="200" /><br /><div class="img_caption">sensor covering</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_sensor_covering.jpg" rel="prettyPhoto[page]" target="_blank" title="sensor covering"></a></div><br />Second part consist of motor driver circuit and the threshold adjusting potentiometer. This part would be soldered on another general purpose board and would be placed on the top of chassis. The reason for placing potentiometer in this part is that it would be easier to adjust sensor threshold. See the pictures below.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Part 2 soldered" border="0" class="caption multithumb" height="170" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_part2_ckt.jpg" title="Part 2 soldered" width="200" /><br /><div class="img_caption">Part 2 soldered</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_part2_ckt.jpg" rel="prettyPhoto[page]" target="_blank" title="Part 2 soldered"></a></div>Now all the chassis and circuit part is done lets combine them all!.<br /><h2>Combining all</h2>Fix the sensor part just in front caster,facing downwards. ensure that there is very less clearance between sensor covering and ground. See the picture below.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Sensor placement" border="0" class="caption multithumb" height="125" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_sensor_placment.jpg" title="Sensor Placement" width="200" /><br /><div class="img_caption">Sensor Placement</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_sensor_placment.jpg" rel="prettyPhoto[page]" target="_blank" title="Sensor Placement"></a></div>Now connect the battery to the circuit and also plugin the motors in there respective connectors. For more information regarding battery and there charging circuit see <cite class="caption" dir="ltr" title="Coming Soon">this tutorial</cite>. I am using two 3.7V Li-ions cells in series for this robot.<br />Small cheap 9 V batteries will not be able to drive this robot for more that 4-5 minutes.<br /><div class="img_caption none" style="float: none; width: 200px;"><img alt="Li-ion battery" border="0" class="caption multithumb" height="170" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_battery.jpg" title="Li-ion battery" width="200" /><br /><div class="img_caption">Li-ion battery</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_battery.jpg" rel="prettyPhoto[page]" target="_blank" title="Li-ion battery"></a></div><div class="img_caption none" style="float: none; width: 200px;"><img alt="Complete Robot" border="0" class="caption multithumb" height="109" src="http://playwithrobots.com/cache/multithumb_thumbs/b_200_200_16777215_00___images_complete_bot.jpg" title="Complete Robot" width="200" /><br /><div class="img_caption">Complete Robot</div><a href="http://playwithrobots.com/cache/multithumb_thumbs/b_800_600_0_00___images_complete_bot.jpg" rel="prettyPhoto[page]" target="_blank" title="Complete Robot"></a></div><br />Adjust the threshold of LDR such that when sensor is on black surface voltage at base of transistor must be less than 0.5Volts. If motors are rotating is reverse direction just change the polarity of that motor. After all this you would be able to make a robot that moves like the one below!<br /><iframe allowfullscreen="" frameborder="0" height="360" src="http://www.youtube.com/embed/o5qvvWnSbkE?feature=player_embedded" width="640"></iframe>  Hope you liked the above tutorial. Subscribe to Lionjetcafe on facebook for more updates.<br />Any questions? Don't hesitate; ask it now at <i>www.lionjetcafe.tk </i><br /><br />Please don't forget to comment your ideas about the post and please like our Facebook page or any other page in any social network below... Thank you !!! Hope you come back again. Good bye !!!! ๑۩۩๑ LIONJET CAFE ๑۩۩๑

Easiest way to make a Simple Line Follower robot

a machine that follows a line, either a black line on white surface or vise-versa. For Beginners it is usually their first robot to play w...

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