Proportional Line Following Explained Pro Preview

We should point out that “duck walking” does not follow the black line but its edge. When the robot is duck walking, it turns to the black line when on white and vice versa.  As a result, the robot is constantly compensating and performs a lot of unnecessary movements.

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  • #777
  • 09 Mar 2018

In the case of proportional line following, we apply the following rule: the greater the distance between the line edge and the robot, the sharper the turn and vice versa. The value at which there is no turn (when the robot is on the edge) is called a setpoint. If the sensor is on “white”, then:

setpoint – sensor value < 0

and the robot will turn in one direction. The greater the difference, the sharper the turn.

If the sensor is on “black”, then:

setpoint – sensor value > 0

and the robot will turn in the other direction. Again, the greater the difference, the sharper the turn.

Relaxation coefficient

The difference between the setpoint and the sensor value is called an error and the corresponding robot movement - a response. The aim of the PLF algorithm is to have a proper response, minimizing the error. We use a coefficient to control how strongly the robot responds to the error. We multiply the error by the coefficient. The result is the response defined by the PLF algorithm. So the greater the coefficient is, the greater the response is. This coefficient is called a relaxation coefficient.

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