Inspired Design

How would you like to have a network of intelligent trashcans around the house? Or a mechanical xylophone that plays itself? A digital sundial might look nice out on the patio.

All of these exotic—if somewhat unlikely—devices were developed by electrical and systems engineering (ESE) students. The projects reflect the school’s emphasis on linking rigorous academic training to “real-world” applications, combined with a spirit of innovative fun.

The projects were developed by students in Dr. Daniel Lee’s ESE 350 class, “Embedded Systems and Microcontroller Laboratory.” The course presents an introduction to the fundamental concepts of embedded computing, which involves the kind of sensors and processors that you find in a microwave or cell phone.

“These devices are ubiquitous in the world, and the course details exactly what makes them work,” says Lee, the Evan C Thompson Term Associate Professor and Raymon S. Markowitz Faculty Fellow in the department of Electrical and Systems Engineering. “What goes on when you push a button on a cell phone to make a call is incredible. You have a microphone that takes your voice and transduces it into an electrical signal, the touchpad then takes the number you need to dial and displays what’s happening on the LCD screen, then transmits that call to a base station that goes to the communications network.”

The thrust of the course is to understand the kind of computation involved, how sensors work, how to make a user display and interface, and how to produce something small and compact. “I try to make it as much real-world as possible, because that’s what gets students excited,” Lee explains. “It ties the classroom to what they’ll do when they get a job in industry or start their own company.”

The lectures cover subjects such as programming theory, interfaces, and how circuits work. All lectures are tied closely to the lab work. For example, as Lee describes how he covers motor interfacing, “I’ll explain the physics of how motors work, what’s involved in making them run, how you get them to be controlled by a processor. It’s not just like a car motor with only an accelerator pedal. At that point, the students go into the lab and build. In the lab they have to make something work. That’s the underlying idea of engineering—you have to make something work. And that’s the rigorous part of the lab component.”

The ESE 350 projects have included hardware video games, an interactive digital door-locking mechanism, and an erector-set like elevator controlled by a keypad. The mechanical xylophone was set up to read a score, and then play it by actuating motors that move the mallets to strike the xylophone keys.

Lee particularly likes having the students take older ideas and update them: the digital solar clock, for example, reads the position of the sun like an old-fashioned sundial, and then uses sensors and computer circuitry to display the time digitally.

In one of the most practical (future) applications, three women students developed the intelligent trashcan. It opens automatically by having the waste-hauler’s foot break an electrical eye set at foot level—except when it’s full. Then the trashcan refuses to open, but instead sends a signal to a human trash collector saying that it needs to be emptied. Better yet, a network of cans can even tell the sanitation engineer in which order the cans should be emptied for maximum efficiency (a variant of the well-known traveling salesman problem).

Lee’s students may be designing smarter trash cans, but they aren’t talking trash. In courses like his, students use academic rigor to forge a broad range of ideas and elements, both practical and theoretical, into solid, useful realities. That, as Lee notes, is the core of engineering.

Credit: Penn Engineering Magazine, “Inspired Design,” by Derek Davis.

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