As iRobot Corp.'s second-generation Looj makes its debut, the engineering challenge behind thegutter-cleaning device was to bolster its ability to dislodge and break upclogged leaves and debris in a much more efficient fashion.

Key to the updated model is a new, anti-flipping,three-stage auger that delivers more power for cleaning along with arefashioned internal antenna and new tread design, both aimed at helping thegutter-cleaning robot avoid getting stuck on external debris or gutter straps,according to iRobot officials.

While the Looj engineering team took advantage of aninternal gutter lab to explore new designs, it was the comprehensive customerfield test program, which helped the development group zero in on the bestapproach. "The challenge with anything in robotics is the unconstrainedenvironment you're going into," says Zivthan Dubrovsky, engineer andproduct manager at iRobot for Looj. "It's not about just simply solving aproblem of how to throw some object out of the gutter, but rather how to dealwith all the various types of debris you encounter along with how to best putthe robot into the gutter. It's the unknowns that make the task verychallenging."

Retooling the auger, the key component that moves thedebris, was a top priority in the updated robot. In its gutter lab, iRobotconstructed test beds that explored about 20 to 30 different augers on alltypes of gutter styles and debris types. iRobot used PTC's Pro/ENGINEER 3-D CADprogram to model the different auger types and then employed rapid prototypingtechniques and CNC machines to create actual prototypes of the most promising,which were then field tested. "We explored auger design through unconstrainedbrainstorming, testing out everything from what's the best profile of thebristles that sweep to the blade that agitates," Dubrovsky says. "We looked atmetal wings and scoops and other ways to remove [the debris] and tested themagainst all the different gutter styles to come up with a style that worked forall of them."

Even if a design worked in the gutter lab, it didn't mean itwas a lock once it went into customer field tests. Consider the tread design onthe new Looj. Once the unit was put out to test in the field, the iRobot teamfound it often got stuck underneath the gutter straps. The team went back tothe drawing board and redesigned the tread pattern to be higher and thicker,allowing for greater clearance. As always, there was an engineering tradeoff:The new tread pattern ended up drawing more power from the robot than previousdesigns, Dubrovsky admits.

The third major change in the next-generation Looj designwas the antenna. The development team wanted to bring the RF antenna designinside the robot, another step to avoid getting tangled up in gutter strapping.Yet an internal antenna design required some creativity to ensure the signalwould perform optimally and give the robot sufficient range. The end result wasa symmetric antenna profile design, which didn't compromise range and includesa pattern that improves its ability to transmit RF signals even within the enclosed"cage-like environment" of the robot and aluminum gutter. "We got feedback fromRF engineers and then it was trial and error tweaking the design and fieldtesting with consumers," Dubrovsky says.

Given the complexity of integrating the Looj's mechanical,electrical and software systems, it was imperative that all the differentdisciplines remain in the loop on design changes. PTC's Windchill PLM platformserved as the central repository for both MCAD and ECAD files, althoughsoftware changes were housed in a separate system. Weekly team meetings todiscuss design changes, along with the PLM system, were essential for keepingthe engineering team updated on the status of changes in any of the disciplinesalong with any other modifications to the design that were initiated by fieldtests. "When you have late breaking changes, you have to have a system capableof accommodating both late design changes and quality improvements," Dubrovskysays. "That's where Windchill comes in."