A presence robot with Chromium, WebRTC, Raspberry Pi 3 and EasyRTC

Here’s how to make a presence robot with Chromium 51, WebRTC, Raspberry Pi 3 and EasyRTC. It’s actually very easy, especially now that Chromium 51 comes with Raspian Jessie, although it’s taken me a long time to find the exact incantation.

If you’re going to use it for real, I’d suggest using the Jabra 410 speaker / mic. I find that audio is always the most important part of a presence robot, and the Jabra provides excellent sound for a meeting of 5 – 8 people and will work for meetings with larger groups too. I’ve had the most reliable results using a separate power supply for the Jabra, via a powered hub. The whole thing still occasionally fails, so this is a work in progress. You’ll need someone at the other end to plug it in for you.

I’ve had fair success with a “portal” type setup with the Raspberry Pi touchscreen, but it’s hard to combine the Jabra and the screen in a useful box.


As you can see, the current container needs work:


Next things for me will be some sort of expressivity and / or movement. Tristan suggests emoji. Tim suggests pipecleaner arms. Henry’s interested more generally in emotion expressed via movement. I want to be able to rotate. All can be done via the WebRTC data channel I think.

You will need

  • Raspberry Pi 3 + SD card + 2.5A power supply
  • Jabra Mic
  • Powered USB hub (I like this one)
  • A pi camera – I’ve only tested it with a V1
  • A screen (e.g. this TFT)
  • A server, e.g a Linode, running Ubuntu 16 LTS. I’ve had trouble with AWS for some reason, possibly a ports issue.


Set up the Pi

(don’t use jessie-lite, use jessie)

diskutil list
diskutil unmountDisk /dev/diskN
sudo dd bs=1m if=~/Downloads/2016-09-23-raspbian-jessie.img of=/dev/rdiskN

Log in.

sudo raspi-config

expand file system, enable camera (and spi if using a TFT) and boot to desktop, logged in

Update everything

sudo apt-get update && sudo apt-get upgrade

Set up wifi

 sudo pico /etc/wpa_supplicant/wpa_supplicant.conf

Add drivers

sudo pico /etc/modules

Add V4l2 video drivers (for Chromium to pick up the camera): argh

sudo nano /etc/modprobe.d/bcm2835-v4l2.conf
options bcm2835-v4l2 gst_v4l2src_is_broken=1

Argh: USB audio

sudo pico /boot/config.txt 

#dtparam=audio=on ## comment this out
sudo pico /lib/modprobe.d/aliases.conf
#options snd-usb-audio index=-2 # comment this out
sudo pico ~.asoundrc
defaults.pcm.card 1;
defaults.ctl.card 0;

Add mini tft screen (see http://www.spotpear.com/learn/EN/raspberry-pi/Raspberry-Pi-LCD/Drive-the-LCD.html )

curl -O http://www.spotpear.com/download/diver24-5/LCD-show-160811.tar.gz
tar -zxvf LCD-show-160811.tar.gz
cd LCD-show/
sudo ./LCD35-show

Rename the bot

sudo pico /etc/hostname
sudo pico /etc/hosts

You may need to enable camera again via sudo raspi-config

Add autostart

pico ~/.config/lxsession/LXDE-pi/autostart
@lxpanel --profile LXDE-pi
@pcmanfm --desktop --profile LXDE-pi
@xscreensaver -no-splash
@xset s off
@xset -dpms
@xset s noblank
#@v4l2-ctl --set-ctrl=rotate=270 # if you need to rotate the camera picture
@/bin/bash /home/pi/start_chromium.sh
pico start_chromium.sh
#@rm -rf /home/pi/.config/chromium/
/usr/bin/chromium-browser --kiosk --disable-infobars --disable-session-crashed-bubble --no-first-run https://your-server:8443/bot.html#$myrandom &

Assemble everything:

  • Connect the USB hub to the Raspberry Pi
  • Connect the Jabra to the USB hub
  • Attach the camera and TFT screen

On the server

Add keys for login

mkdir ~/.ssh
chmod 700 ~/.ssh
pico ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Install and configure Apache (I used this guide for letsencrypt)

sudo apt-get install apache2
sudo mkdir -p /var/www/your-server/public_html
sudo chown -R $USER:$USER /var/www/your-server/public_html
sudo chmod -R 755 /var/www
nano /var/www/your-server/public_html/index.html
sudo cp /etc/apache2/sites-available/000-default.conf /etc/apache2/sites-available/your-server.conf
sudo nano /etc/apache2/sites-available/your-server.conf
<VirtualHost *:80>     
        ServerAdmin webmaster@localhost
        ServerName your-server
        ServerAlias your-server
        ErrorLog ${APACHE_LOG_DIR}/your-server_error.log
        CustomLog ${APACHE_LOG_DIR}/your-server_access.log combined
RewriteEngine on
RewriteCond %{SERVER_NAME} = your-server
RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,QSA,R=permanent]
sudo a2ensite your-server.conf
sudo service apache2 reload
sudo service apache2 restart

Add certs

You can’t skip this part – Chrome and Chromium won’t work without https

sudo apt-get install git
sudo git clone https://github.com/letsencrypt/letsencrypt /opt/letsencrypt
cd /opt/letsencrypt
./letsencrypt-auto --apache -d your-server
/opt/letsencrypt/letsencrypt-auto renew >> /var/log/le-renew.log
sudo /opt/letsencrypt/letsencrypt-auto renew >> /var/log/le-renew.log
sudo mkdir /var/log/
sudo mkdir /var/log/lets-encrypt

Auto-renew certs

sudo /opt/letsencrypt/letsencrypt-auto renew >> /var/log/lets-encrypt/le-renew.log
crontab -e
# m h  dom mon dow   command
30 2 * * 1 /opt/letsencrypt/letsencrypt-auto renew >> /var/log/lets-encrypt/le-renew.log

Get and install the EasyRTC code

Install node

curl -sL https://deb.nodesource.com/setup | sudo bash -

sudo apt-get install -y nodejs

Install the easyrtc api

cd /var/www/your-server/
git clone https://github.com/priologic/easyrtc

Replace the server part with my version

cd server
rm -r *
git clone https://github.com/libbymiller/libbybot.git
cd ..
sudo npm install

Run the node server

nohup node server.js &


Boot up the pi, and on your other machine go to


in Chrome.

When the Pi boots up it should go into full screen Chromium at https://your-server:8443/bot.html  – there should be a prompt to accept the audio and video on the pi – you need to accept that once and then it’ll work.


Camera light doesn’t go on

Re-enable the camera using

sudo raspi-config

No video

WebRTC needs a lot of ports open. With this config we’re just using some default STUN and TURN ports. On most wifi networks it should work, but on some restricted or corporate networks you may have trouble. I’ve not tried running my own TURN servers, which in theory would help with this.

No audio

I find linux audio incredibly confusing. The config above is based around this answer. YMMV especially if you have other devices attached.