PID is the most popular method for programming line-following robots. It’s a bit complex, so this tutorial is longer, as we’ll break it down into steps and explain each element of the equation.
This approach to programming line-following robots is not ideal for beginners. Attempting to learn this as a first step in competition preparation may give a misleading impression of the competition's complexity and could discourage students from learning the necessary skills to compete in this category.
PID stands for Proportional Integral Derivative control. As the name suggests, this is a modular type of control that consists of three components:
Proportional component "P" - Also called "Error." This is the amount the robot has deviated from the line. We calculate it by measuring how much the sensor’s reflected light differs from the "Target Value" the robot is trying to follow.
P = Error
Error = Target Reflected Light Value - Measured Reflected Light Value
Integral component "I" - This is the sum of all Error values. Since Error can be positive or negative, this sum naturally trends toward zero. It adjusts the sharpness of the robot's turns based on how far it deviates from zero. Usually, this component is negligible for smaller robots, so many choose to ignore it entirely.
I = I + Error
Derivative component "D" - Also called "Differential." This value helps prevent overcorrection. It’s calculated by measuring the difference in Error (the Proportional component) between the current and previous measurements.
D = Error - Previous Error
These three components are added together to produce our PID value. In formula form, it looks like this:
PIDvalue = P + I + D
However, the raw values are rarely ideal for every robot, field, sensor, and wheel size. Each component needs to be proportionally adjusted to suit the specific robot, achieved by simple multiplication:
PIDvalue = P*Kp + I*Ki + D*Kd
Kp, Ki, and Kd are values chosen to optimize performance. Several methods exist to determine these values; here, we’ll use the simplest, a five-step testing method:
Ultimately, we obtain a PID value that we can use to adjust the motors’ speeds from a preset base speed.
Този Урок е използван в следните курсове и занятия.
This is the Line Following course, where you’ll explore essential techniques to help your LEGO robot follow a line with accuracy and stability! We will begin by covering the fundamental concepts of line following, starting with basic wobble line following, which teaches how robots detect and respond to lines. Then, we'll progress to more advanced methods like proportional line following, allowing smoother tracking by adjusting speed based on error values. Finally, you'll dive into the widely-used PID line following technique, where you'll learn how to tune parameters for optimal robot performance. Whether you're a beginner or looking to enhance your robotics skills, this course will guide you through building, coding, and refining your robot's line-following capabilities.
PID is the most popular method for programming line-following robots. It’s a bit complex, so this tutorial is longer, as we’ll break it down into steps and explain each element of the equation.
This approach to programming line-following robots is not ideal for beginners. Attempting to learn this as a first step in competition preparation may give a misleading impression of the competition's complexity and could discourage students from learning the necessary skills to compete in this category.