Wi-Fi robot

A wi-fi controlled robot with live video feed.

This was proposed and directed by myself over a year at the Polytech Paris-Sud school, but I could not have completed the work alone. Our team was composed of Jean-Marc Abbas (IT), Charles Leroux (EE), and myself (IT).

This project also uses a number of free programs, the authors of which we greatly thank.

A demo video, photos and detailed documents (in French) are available in the documents/ directory.

Usage

Hardware

You'll need :

• A Raspberry Pi 3 (we thought the extra computing power would be helpful)
• An official Raspberry camera
• 2x Phone power banks, rated 3A (the RPi3 won't work reliably with less)
• A robot chassis. To save time, we used a turnkey chinese chassis "Tchang DD1-1" bought on e-bay for 40€. It included motors, transistors for control, speed sensors (unused) and PWM.
• A whole bunch of cables and a creative spirit

The RPi will send commands through its GPIO ; most complicated things are, in our case, either handled software-side or by our chassis.

Software

You'll need :

• A fresh Raspbian install (Debian being the best distro anyway)
• the picamera utility
• the ever-useful FFMpeg (and NOT avconv, which briefly replaced it by default on Debian for doubtful reasons)
• Python 3
• the RPi.GPIO library
• The Tornado web server
• The JSmpeg decoder
• A modern web browser on the client end (>2011 should do).

Potentially, everything could be done in Python. But it's simpler to manage the different components through the console, hence the bash script.

Essentially, the idea is to get the (x264) output from picamera, reencode it to MPEG1 with FFMpeg, and pass that to Tornado. Tornado (being non-blocking and all) will open two WebSockets (one for the video feed and one for the commands) with the client, connected via wi-fi. This works with any number of clients (although there is currently no special mechanism, so the robot will just execute all commands, wherever they come from).

The simplest way to use all this is to put the files in a user's home, remotely SSH, and execute the script, maybe with something like nohup. It would be cleaner to do with automatically on boot (and why not to also start a wi-fi hotspot for clients to connect to).