When you hear the task “program the robot to follow a black line,” you’ll most likely imagine a program that works like this:
This program may seem logical and will probably work—at least at first. The first part, where the sensor detects black and the robot moves forward, is simple:
However, the second part—when the sensor is no longer over the black line—is quite difficult, if not impossible to implement directly. Let's say the robot is to the right of the line:
In this case, the robot needs to turn left to return to the line. Now, if the robot is on the left side of the line:
It must turn right to return. That’s all good, but here’s the problem: the sensor values on both sides of the line (left and right) are very similar—sometimes even identical. So, the robot cannot tell which way to turn.
That’s why, when we say we're programming the robot to “follow the line,” we’re actually simplifying the truth. What the robot really does is follow one of the edges of the line.
The edge is an imaginary boundary between the black line and the background (shown here as red dashed lines). Every line has two edges—one on the left and one on the right.
When following an edge using only one color sensor, the robot can determine if it's on the left or right side of that edge. For example, if the robot is following the right edge of the black line:
So, the proper logic for following a black line should be: if the sensor reads black, turn right; otherwise, turn left. This decision-making process is continuously repeated in a loop.
Continue to the next exercises and try it out—see if your robot can follow the line correctly!
This Tutorial is used in the following courses and lessons
If you are working with students and you want to introduce Robotics to your class or you want to mentor a FLL team, but you are insecure about your technical knowledge in the Robotics field, then this is the right place for you. Having in mind teachers' busy schedule, we have design two different schedules and added an option to design one just for you. FLLCasts's Mindstorms EV3 Robotics Online Training is the perfect match for any teacher.
After the completion of each task the participant has to upload his solution for verification.
Today we will focus on another block which will allow our robots to make decisions. This block is in the Flow Control palette and is called “Switch”.
The second level of the Robotics with LEGO curriculum for students from fifth to twelfth grades.
Students build multiple robots with thread chains and become familiar with the physical concepts of momentum and center of gravity. The concept of gears, their use and basic constructions involving gears are studied.
The new concept of "condition" is introduced in programming. Robots are becoming smarter as they can make complex decisions on their own. "Spy robots" follow their targets and avoid being noticed. This level introduces the light sensor which the robots use to recognize the colors of the objects they are looking for. Robots can stop on a black line and follow a route marked with a colored line on the floor.
The spy's most complex mission in the end of the level is to turn into a sumo wrestler and defeat any other robot in the ring.
If you are working with students and you want to introduce Robotics to your class or you want to mentor a FLL team, but you are insecure about your technical knowledge in the Robotics field, then this is the right place for you. Having in mind teachers' busy schedule, we have design two different schedules and added an option to design one just for you. FLLCasts's Mindstorms EV3 Robotics Online Training is the perfect match for any teacher.
After the completion of each task the participant has to upload his solution for verification.
In this episode, we introduce a LEGO Mindstorms EV3 version of competition robot construction. It is a modular construction, with medium motor for additional attachments and two light or colour sensors for orientating on the field.
The firfth level of the Robotics with LEGO curriculum for students in second, third or fourth grades.
The students build many robots with chain-treads. The Color Sensor is introduced and robots use it to recognize the colors of the objects around them. Students learn about gears, basic gear constructions, and their application. Robots now can stop on a black line and can follow a line using their sensor.
The firfth level of the Robotics with LEGO curriculum for students in second, third or fourth grades.
The students build many robots with chain-treads. The Color Sensor is introduced and robots use it to recognize the colors of the objects around them. Students learn about gears, basic gear constructions, and their application. Robots now can stop on a black line and can follow a line using their sensor.
In the next lesson we usually do a graduation. Write down your impressions about the students and the reasons why they have the grades you gave them.
Welcome to an introduction to the SPIKE Prime set! In this course, you’ll find 7 step-by-step 3D building instructions for SPIKE Prime robots, designed to help you explore the full potential of the base set. Once you've built them, you can bring them to life with our fun programs—these range from simple tasks like moving forward to more complex actions like detecting the nearest object.
And if you're ready for a challenge, we’ve also prepared some advanced tasks! These will encourage you to research and experiment with both the programs and the robot itself. Of course, you're always welcome to add your own creative touches and enjoy the process along the way.
