This one looks to be unnecessarily complicated and expensive.  Robotic mowers have been in use in Europe for over a decade. I got my Husqvarna Automower four years ago and it works perfectly even in the rain.  They're now on sale on Amazon for around $650. Uses an easily installed perimeter wire that disappears underground in a short time. If the mower touches an obstruction of any kind it stops and heads in another direction. Safe, silent, efficient.