Using Raspberry Pi Python to program Rotary Encoder and PID algorithm with FlexiRover 520 Motor

In this tutorial, we will read the two Rotary Encoders’ position in FlexiRover robot car with Raspberry Pi control board.

Prerequisite:
We suppose you have installed the 520 motor and connected the motor wires to Raspberry Pi I/O Shield as per following tutorial:
https://osoyoo.com/2024/05/06/v5-generic-robot-car-for-raspberry-pi-running-with-mecanum-wheel/

Left and Right Encoders’wire Connection:

Above positions are the pin map of Magic I/O Shield GPIO pins which exactly matches Raspberry Pi GPIO layout .

Software Installation:
Download the encoder.py program file by typing following command in terminal (either ssh or putty terminal):

wget https://osoyoo.com/driver/v5car/encoder.py

After download the code, type following command in terminal:

python encoder.py

Now rotate your left encoder wheel or right encoder wheel, you will see following message in your terminal:

Encoder 1 Position: -49
Encoder 1 Position: -50
Encoder 1 Position: -51
Encoder 1 Position: -52
Encoder 1 Position: -51
Encoder 1 Position: -52
Encoder 1 Position: -51
Encoder 1 Position: -52
Encoder 1 Position: -53
Encoder 2 Position: 1
Encoder 2 Position: 2
Encoder 2 Position: 3
Encoder 2 Position: 4
Encoder 2 Position: 5
Encoder 2 Position: 6
Encoder 2 Position: 7
Encoder 2 Position: 8
Encoder 2 Position: 9
Encoder 2 Position: 10

Encoder 1 is the right motor encoder, Encoder 2 is the left motor encoder. By reading the value, you can calculate the left motor and right motor rotation speed which is quite important to PID algorithm.

PID algorithm Sample Code:

Based on above hardware and encoder installation, we can apply a PID program to make the car move straightly forward.
Type following command in terminal and download pid.py python code:

wget https://osoyoo.com/driver/v5car/pid.py

Type following command to run pid.py in terminal

python pid.py