As iRobot Corp.'s second-generation Looj makes its debut, the engineering challenge behind the gutter-cleaning device was to bolster its ability to dislodge and break up clogged 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 a refashioned internal antenna and new tread design, both aimed at helping the gutter-cleaning robot avoid getting stuck on external debris or gutter straps, according to iRobot officials.
While the Looj engineering team took advantage of an internal gutter lab to explore new designs, it was the comprehensive customer field test program, which helped the development group zero in on the best approach. "The challenge with anything in robotics is the unconstrained environment you're going into," says Zivthan Dubrovsky, engineer and product manager at iRobot for Looj. "It's not about just simply solving a problem of how to throw some object out of the gutter, but rather how to deal with all the various types of debris you encounter along with how to best put the robot into the gutter. It's the unknowns that make the task very challenging."
Retooling the auger, the key component that moves the debris, was a top priority in the updated robot. In its gutter lab, iRobot constructed test beds that explored about 20 to 30 different augers on all types of gutter styles and debris types. iRobot used PTC's Pro/ENGINEER 3-D CAD program to model the different auger types and then employed rapid prototyping techniques and CNC machines to create actual prototypes of the most promising, which were then field tested. "We explored auger design through unconstrained brainstorming, testing out everything from what's the best profile of the bristles that sweep to the blade that agitates," Dubrovsky says. "We looked at metal wings and scoops and other ways to remove [the debris] and tested them against all the different gutter styles to come up with a style that worked for all of them."
Even if a design worked in the gutter lab, it didn't mean it was a lock once it went into customer field tests. Consider the tread design on the new Looj. Once the unit was put out to test in the field, the iRobot team found it often got stuck underneath the gutter straps. The team went back to the 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 previous designs, Dubrovsky admits.
The third major change in the next-generation Looj design was the antenna. The development team wanted to bring the RF antenna design inside the robot, another step to avoid getting tangled up in gutter strapping. Yet an internal antenna design required some creativity to ensure the signal would perform optimally and give the robot sufficient range. The end result was a symmetric antenna profile design, which didn't compromise range and includes a 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 from RF engineers and then it was trial and error tweaking the design and field testing with consumers," Dubrovsky says.Given the complexity of integrating the Looj's mechanical, electrical and software systems, it was imperative that all the different disciplines remain in the loop on design changes. PTC's Windchill PLM platform served as the central repository for both MCAD and ECAD files, although software changes were housed in a separate system. Weekly team meetings to discuss design changes, along with the PLM system, were essential for keeping the engineering team updated on the status of changes in any of the disciplines along with any other modifications to the design that were initiated by field tests. "When you have late breaking changes, you have to have a system capable of accommodating both late design changes and quality improvements," Dubrovsky says. "That's where Windchill comes in."