Intermittently I have an issue with some of my webcams connected to my Ubuntu server. The devices disappear as if they are disconnected. I found a simple workaround for this was to run the command:
udevadm triggerSimple scheduling of this command using crontab achieves a more permantant workaround:
sudo crontab -e
0 5 * * * udevadm triggerThis cron is set to run at 5am each morning