Robot to wash high-rise windows
As long as buildings have windows, engineers will fret about how best to keep them clean. Rice University engineering students are no exception and are working on better ways to keep skyscrapers shiny.
The WashBOT team of seniors based at Rice’s Oshman Engineering Design Kitchen is part of a multiyear robotics project to automate the process of cleaning recessed windows in buildings that present problems for more traditional washers, both human and machine.
The students—Julia Bleck, Michael Liu, Erin O’Malley, and Andria Remirez—were joined by colleagues from Tunisia, Nourelhouda Derbeli and Ali Abdmouleh, both students at the National School of Engineers of Sfax. They spent the fall semester communicating their ideas via Skype, but Derbeli and Abdmouleh are studying side by side with their teammates at Rice this spring.
Washing a window seems simple for a person, but it’s complicated for a robot. First, one has to get the machine in position. Then there are variables to account for: the size of the window, depth of the recess, application of the cleaning agent … and the squeegee.
“That’s the most difficult part,” Remirez says.
The students were charged with biting off a piece of the engineering challenge that could be handled by a student team within a year, says Fathi Ghorbel, a Rice professor of mechanical engineering and materials science and of bioengineering and the team’s adviser. “This is a problem with a large scope that usually requires a company, several years and a lot of funding to solve,” he says. “So the challenge to the students was to decide on the scope and deliver, because their grade depends on it.”
So the team got to the heart of the matter: the cleaning.
“We had to narrow it down to something we could physically create,” Bleck says. “We decided to focus on recessed windows because there’s nothing in the market that cleans them right now. And then we narrowed it to washing one portion of one window. Moving within a window is in itself a project; moving from window to window is another project.”
The Rice system soaps the window with a sponge-like mop on a horizontal track and follows with a squeegee to finish the job. “We have designs to move the robot down the window to do the next horizontal pass,” Bleck says, but that job may be left to the next team.
“We’ve had to do a lot of integration between the attachment system and the cleaning system,” O’Malley says. “There are a lot of things to do, but they all depend on other things.”
The robot’s tension system can be adjusted for window widths. Sensors stop the brush at the end of the glass, rotate the mechanism and move it back across. “So there’s no need to reprogram the robot to have it know the size of the window,” O’Malley says.
The team spent the fall testing cleaning materials, watching and talking to window washers and visiting car washes to study how glass gets clean. “A lot of the current solutions use big, round rotating brushes, which work really well for flat-front buildings but not as well for buildings that have things sticking out between the windows,” O’Malley says.
“So we tried to make the robot as close to what a window washer would do: spray water, wipe it down with a sponge and use a squeegee,” Remirez says. “Getting the applied pressure right has been the hardest part. We did a lot of research for that.”
The project serves the senior engineering design requirement for the Tunisian students, who rarely have the chance to work in teams. “They typically work on their own with an industrial partner or with a researcher within the university,” Ghorbel says. Another group in Tunisia is working on the robot’s locomotion system, he says.
The international aspect of the project is part of a larger effort by Ghorbel to establish long-term collaborations with engineering schools overseas. He began his iDesign initiative during a yearlong leave to work with oil and gas giant Schlumberger in Paris on mechatronics and robotics issues and to establish connections between the company and academia.
“The idea of capstone design is unique to the U.S. curriculum, asking students to apply the knowledge they have acquired to go from an idea to a prototype,” Ghorbel says. “At Rice, we’re doing that extremely well, not only from a technical point of view but also as a way to encourage entrepreneurship, with the Rice Center for Engineering Leadership and the Rice Alliance.
“When I talked about these things in Paris, Schlumberger said, ‘Let’s do an international version,’” he says. Thus far, the project has worked with universities in the United Arab Emirates and Tokyo as well as France and Tunisia, the latter with support from the U.S. State Department, he says.
Source: Rice University