Robot

A python-controlled playground for Lego Mindstorms ev3 robotics. This can form a base for AI projects.

Prequisites

A Lego Mindstorms ev3 kit.
An install on the ev3 brick of the brilliant ev3dev ** Use the "stretch" install to support the ev3dev2 python library.
Some form of robot with a left motor on InputA and a right motor on InputB.

Background

The project works on a client-server basis. There is a folder called brick that stores the code for the ev3 brick and a folder called computer that stores the code for a server to communicate with the brick.

The ev3dev site provides a tutorial that uses MQTT. It turns out that MQTT is not great for real-time communication as it is designed for asynchronous communication. The present project chooses to use a TCP/IP connection instead.

The general pattern is we send data between the client and the server as an encoded JSON string.

Install on Computer

Create a new virtual environment using Python or Conda.

conda create --name robot python

Setup environment variables for the server IP address and port to use for the TCP connection. For conda we can use the instructions here. Then edit the files as instructed and set the following variables: HOST=[IP Address of server] PORT=[Port to use on server] and unset these in the deactivate file.

Install on Brick

Copy the files from the brick folder into the home directory of the robot user. I use SFTP to access the file system and just copy the files across.

Running Remote Control

Run the Brain on the Server

Navigate to the top of the directories (e.g. the robot folder).

Run python - python. Import the RobotBrain then run wait_for_connect:

from computer.socket_server import RobotBrain
brian = RobotBrain()
brian.wait_for_connect()

Run the Brick

SSH into the robot: ssh robot@ev3dev.local Then when logged in check the HOST and PORT env variables match. Then run:

python3
from brick_client import Robot
r = Robot()

On the server you should see a connection register: Connection address: ('[Robot IP Address', X)

Now run - r.remote_control() on the robot and brian.remote_control() on the server. You should be able to use the a-w-s-d keys to move L-F-B-R!

benhoyle / robot