This is a pc mouse. It gives a travel distance in x-axis and y-axis. It can't see rotation.

If the mouse is connect in a Linux os, we can read the values in dev/input/mice.

import struct

with open("/dev/input/mice","rb") as fd:
    while True:
        # unpack data to have x and y
        y,x = struct.unpack("xbb",fd.read(3))

The distance given is not a distance in cm, we need to use a multiplication parameter to have the distance in cm.

We test the it on the 2019 eurobot. You can find the files with ROS in the little_robot branch of Eurobot-2019, little_robot/ROS_packages/R&D/mouse/src.

• Distance traveled compute on the field.

• The raspberry must be fast enough.
• It's not better than the encoder of the mechanum wheels.
• It didn't see the rotations.