For the moment, I am ignoring input from the two front and rear/side lidar units (Arduino 1, 2, 6 and 7).

These units sometimes "detect" something I can't see. Actually, Max (my Aibo robot dog) barks at unknown things (and displays little "x's" on his map) while Astro (Amazon robot) will circle around "nothing visible" in the middle of the large open floor. 

Curious, but something for another day.