Hi, thank you for providing such a great project!
This is not an issue but I am interested why you used serial communication between Raspberry Pi and Arduino?
Is there a specific reason you did not use rosserial_arduino to setup a ros node on the Arduino?

Hi, this is a very useful project. I'm currently trying to replicate it and test it on just one motor on the arduino code side. So I have commented out only the lines that assign values to the motor in the arduino code and I'm trying to run it. I see the values being printed on the motordriver.py window, but when I do rostopic echo /arduino, nothing is being printed and my motor isn't running either.

My rostopic list shows arduino topic. Kindly help.