Team 10 SmarTrash members: Yaniv Ophir, Andrew Hagedorn, Joseph D’Errico, and Vyas Venkataraman

Trash is big money and trash collection from public parks is a serious budget drain. The SmarTrash team addressed this issue by designing a trash can that can sense when it’s full and communicate this information to a central network, enabling targeted trips to only those trash cans which are full.

For their market research, the group surveyed 50 parks around the country and received 13 responses. One park in St. Paul, Minnesota reported that every trip to empty a trash can costs $5.33, whether or not the trash can needs to be emptied.

“The City of New York Parks and Recreation, for example, estimates that they spend over 8 million dollars annually on trash collection in the Borough of Manhattan’s parks alone,” said Yaniv Ophir. “They don’t even use bags because it costs too much to put new bags in every time.”

Money isn’t the only factor involved: garbage trucks average 2.8 miles per gallon and spew exhaust into parks. The most common practice in park waste management is for a park official to visit each trash can and empty it if necessary. To the SmarTrash team’s knowledge, no park in the United States employs a centralized method of notifying staff when trash cans are full.

The New York park service is so interested in the group’s project that the city invited them to a trade show on May 17.

“We’ll be on the stage with people who do this for a living; commercial products in the public trash collection industry. Nobody really does what we do,” said Joseph D’Errico. According to the team, the closest alternative to SmarTrash is a self-compacting trashcan that needs to be hooked to a power line. SmarTrash’s prototype costs just $212, with an additional one-time server cost of $325.

“What we’re focused on is providing information to the park officials. They can see which areas are heavily trafficked and then add more trash cans,” said D’Errico.

SmarTrash cans have a range of 300 feet, and can be placed further apart with extender motes between them. Solar panels lay flat on the outside of the lid and power two AA batteries that can last up to 23 months using just 4 hours of sunlight a day to recharge.

SmarTrash Construction

The cans sense when they are full by using two types of infrared sensors. Infrared light emitting diodes and phototransistors examine a plane at the top of the trashcan, and an infrared distance sensor looks down into the trashcan from the lid.

“The most challenging part of the project was the motes,” said Ophir. “We found problems in our original algorithm and it was a big team effort to rewrite it, redo it, and retest it.”

The trash cans are networked together with Crossbow MICA2 motes, which enables multiple sensors distributed over a large area to wirelessly transmit data to a central server. The data is forwarded from trash can to trash can until it reaches the main server and the motes figure out how to form the most efficient network by themselves.

“Each trash can acts as a node in the network. The trash cans themselves form the network, so you don’t need any external hardware,” said Ophir. The motes can perform multihopping, which allows a mote out of range of the server to pass its information from mote to mote until it is within range. The network can also heal itself by bypassing motes that are damaged to find alternative routes.

The server displays trash can status via a Google Maps-based web interface. Each status has an icon; green for empty, yellow for almost full, red for full, and an exclamation point for maintenance. To view the status of cans throughout the park, the user refreshes the map, which triggers the motes to send the latest information to the server.

“We reported a 99.3% ability to report the data back with one failed attempt,” said D’Errico.

Placing technology is a public park could tempt thieves and vandals, but the team has a provision for this if the project moves beyond the prototype stage.

“We thought about hinging the lid to the trash can so it would be part of the trash can. Ideally, we would make it so it was hidden by a door and you wouldn’t even know there was something mechanical about the trash can,” explained Ophir.

Team 10 designed their project for entry into the 7th annual Computer Society International Design Competition (CSIDC). The team is among 10 groups that will compete in the CSIDC 2006 world finals in Washington, DC on June 29. Other competing teams hail from China, India, Poland, Romania, Jordan, and two other teams from the U.S. Sponsored by the IEEE and Microsoft, the competition aims to advance excellence in computer science and computer engineering education by encouraging student teams to design and implement computer-based solutions to real-world problems.