I want to have the title "world's best duct cleaning equipment" for my company's line of robots, and have studied the challenges of hundreds of duct cleaners in person, talked to thousands internationally about their challenges in work and with their equipment, and these three robots are the result.
https://youtu.be/a1gaw4trqgE
Residential Duct Cleaning Robot:

http://www.roboticsdesign.qc.ca/mobile-robots/hvac-cleaning-and-inspection/ari10/
Features: climbs walls, HD cameras
Commercial Duct Cleaning Robot

http://www.roboticsdesign.qc.ca/mobile-robots/hvac-cleaning-and-inspection/ari50/
Features: fits in 3.6 x 6" ducts, single cable for air, control and power, light weight
Industrial Duct Cleaning Robot

http://www.roboticsdesign.qc.ca/mobile-robots/hvac-cleaning-and-inspection/ari100/
Features: powerful articulated arm (moves in 4 directions), climbs 5" obstacles, most efficient cleaning method for 6" x 8" - 4' x 4' ducts (or larger)
I haven't seen much of anything on the Globalspec site for duct cleaning equipments, and the "duct cleaning robots" terms returns 0 results.
Any air duct cleaners here? Have you ever tried robotics? What is the best duct cleaning equipment in the world?