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SEAL: System of Electromagnetic Assisted Locking

A smart trash can that will SEAL itself when knocked over by wind

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The students of the Granada Hills Charter High School live in a region of Southern California which regularly experiences intense winds with climbing numbers of large-mammals in residential areas. This drives trash bins to fall over, spilling the contents into the area, which makes its way to various ecosystems, including the Pacific Ocean. To combat this, the team designed an gyroscope-driven locking system entitled the System of Electromagnetic Assisted Locking (SEAL). The current status of the invention meets original goals set by the team since it can operate for almost a year and automatically lock trash bins in the event of a knock-over. In the coming stages, the team intends to continue to maximize power through the addition of a solar-panel, the maximization of space through the efficient production of a PCB, the further improvement of the case’s attachment, and the optimization of the modular case.

Iteration #1 

In our first iteration we used an arduino uno, a 600N electromagnet, a 5V relay, an arduino-compatible accelerometer/gyroscope breakaway board (MPU6050) and a solderless breadboard.  We contained the device in a 3D printed case which we attached with nuts and bolts through holes drilled into the side of the trash can. The device is powered both by a 9V battery for the arduino and 4 AA batteries to power the electrmagnet., however due to the power demands of the system (largely the arduino itself) and the size of the system we decided to optimize through development of smaller versions. We learned that the contact between the steel plate on the lid and the electromagnetic base unit must be precisely engineered for a reliable locking action to occur. The attachment to the device to the trash can and the alignment of the electromagnet’s base and the armature plate on the lid had slight imperfections and irregularities that were updated in the newer models.

Iteration #2

In our second iteration we switched from the arduino uno to the arduino metro mini and we used a solder-able breadboard to make the breadboard component smaller. These two changes drastically reduced the size of the case.  The gyroscope component has not changed. Additionally, we changed the 5V relay to a transistor to help reduce power consumption and decrease the overall size of the assembly. Finally, the 3D printed case is now modular so that individual components of the design can be separated. The transistor also is connected to a single resistor that will ensure the device can be turned off when uprighted. 

Iteration #3

The team has decided to try an updated solution to our power dilemma.  We have designed a custom PCB and we will begin soldering the components.  In order to solve our power dilemma we needed to switch to a low power microcontroller (PIC16), the BMA400 accelerometer and the BMG250 gyroscope as each of these components uses significantly less power than our previous system.  The new components will require additional capacitors and resistors that we will be soldering.  

Things we considered:

We considered using an arduino trinket. At the time we were trying out the trinket we were using a 5V relay but the trinket did not have a 5V output so it was not functioning in our system.  We then switched from a relay to a transistor to prevent the issue in the future. We have not revisited the trinket in our newer iterations but this could be an area to explore. As a student team, we also found the metro mini to work better with the constraints within our school.  

We considered using button batteries early on but had issues with the power they could provide in our early systems.  

We tested several electromagnets and the most success we have had so far has been with a rectangular 600N electromagnet. We tested several circular electromagnets (ranging from 100-300N) but these didn’t work as well within our system. We discovered that 200N is likely the necessary force that we will need however the additional surface area provided by the stronger 600N rectangular electromagnet 

InvenTeams Final Case PART (1) (1).STL

This CAD model shows the most up to date prototype in a trash can, including the new method of attachment which does not void the warranty of the trashcan.

Standard Tesselated Geometry - 5.23 MB - 08/25/2019 at 13:29

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SEAL Case Ver 1.3.stl

For our updates to the initial prototype we created a slightly modified case that would allow components to be housed in specific compartments.

Standard Tesselated Geometry - 7.89 kB - 08/21/2019 at 13:02

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SEAL Case Ver 1.1 (1).stl

This was our very first case design. It was too large and did not contain individual holders for components.

Standard Tesselated Geometry - 3.01 kB - 08/21/2019 at 13:00

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Full Modular Case 2.0.stl

This is for our most recent prototype. The modular case gives us greater flexibility as the components can be housed separately. The size of the case has also decreased.

Standard Tesselated Geometry - 75.67 kB - 08/21/2019 at 12:47

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  • 1 × Arduino metro mini Thi is currently the smallest arduino we have tested to enable us to maintain the power we need but reduce overall size of the device.
  • 1 × npn transistor s8050
  • 1 × copper wires 20 gauge
  • 1 × MPU 6050 (accelerometer and gyroscope)
  • 1 × electromagnet skyzonal 600N We have found that the rectangular electromagnets outperform the circular electromagnets in our current prototype.

View all 7 components

  • Presenting our device at MIT

    Jeannie08/21/2019 at 12:41 0 comments

    During the 2018-2019 school year, our team was selected as a Lemelson-MIT InvenTeam. Lemelson-MIT InvenTeams are teams of high school students, educators, and mentors that receive grants of up to 10,000 dollars each to provide technological solutions to real-world problems.  We received a 10,000 dollar grant to develop and build our invention, and the opportunity to present our invention at the end of the year at MIT to other InvenTeams and members of the MIT community. At MIT, we were able to see the brilliance of other school’s project as well as presenting our own and sharing our ideas and prototypes. We were able to get advice from members of the MIT community, including graduate students and professors. We received many ideas to guide us in the future of our project and are grateful for the opportunity to showcase our invention from the Lemelson-MIT foundation. 

  • Prototypes moving along!

    Jeannie08/21/2019 at 12:40 0 comments

    New Prototype! We have successfully designed and received our PCB’s and we are very excited to start using them. We have also switched from arduino microcontrollers to pic16 microcontrollers and other new sensors, which will significantly reduce power consumption. We have also discovered a new way to attach our device to the trash can using suction cups, and are excited to test and tinker with them. We have designed a new case to use with the suction cups and have also switched to lithium-polymer batteries to save space and also be sustainable.  The suction cups are important because we found out that physically modifying the trash can voids it's warranty. We have been working on ways to attach our device that will provide enough strength without voiding the warranty. Finally, we moved to a modular case that will give us greater flexibility if we need to exchange or modify components. We are getting the device smaller and smaller with each prototype, and are excited to keep improving our device.

  • Prototype #3 in progress

    Jeannie05/31/2019 at 13:08 0 comments

    May 2013

    We have decided to try a prototype using a PCB design rather than a system of Arduinos. This has meant that we learned to code a new microcontroller in a new language, and we learned a lot about PCB design in the process.  

  • Prototype #2

    Jeannie05/31/2019 at 13:07 0 comments

    April 2019

    Our second prototype is up and running! This prototype is very similar to the original, with the major exception being that this prototype has been reduced in size by switching from an Arduino Uno to an Arduino Metro mini.  Additionally, we have created a new case for the device that is now modular so that we can replace parts of the device more easily.  

  • First Prototype Debuts

    Jeannie05/31/2019 at 13:04 0 comments

    February 2019

    As part of the grant cycle, we held a mid-grant technical review to showcase our invention to stakeholders and the community to receive input and feedback.  At this event we had our first functioning prototype.  The details of the prototype are provided but there are several drawbacks, mainly that it was attached to the trash can by screwing through the front of the can.  This voids the warranty and we are trying to avoid that if possible! 

  • Great News!!!

    Jeannie05/31/2019 at 13:01 0 comments

    October 2018

    We received great news!!! We were selected as one of the Lemelson-MIT Inventeams for the 2018-2019 school year.  This meant that we had $10,000 to spend on our project and we were so excited to begin!

  • School Starts with 10 page paper due

    Jeannie05/31/2019 at 13:00 1 comment

    August 2018

    This year school happens to start right before the final round of applications are due for the grant proposal, meaning the minute we get to school we already have a 10 page paper to write. Luckily we were up to the challenge and we received a bunch of support from our community for making it through the first round.  We had a STEM breakfast to celebrate and local representatives applauded our progress thus far. 

  • The invention begins

    Jeannie05/31/2019 at 12:56 0 comments

    May 2018

    The initial idea for the invention is brought to the coaches and we submitted our application to the Lemelson-MIT Inventeam program.  We were selected to make it past the first round and sent a coach to MIT in June to learn more.  Summer begins and we start planning and gathering details. 

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Jeannie wrote 08/25/2019 at 13:39 point

Thanks for your suggestion! We looked into various gravity features early on and didn't feel they served all our purposes. First, we wanted to be sure to not void the warranty. Second, we want to be able to update the device in the future with additional options controlled by the arduino.  We are hoping to add in some new components this year (including more sensors). 

  Are you sure? yes | no

hackbot wrote 07/19/2019 at 18:59 point

One or two weighted levers to lock the lid would not do the trick?

This might be the right category: https://patents.google.com/?q=E05B15%2f0093

There are locks incorporating a gravity feature that not only allow dumping the bin when locked but also prevent spilling when tipped.

  Are you sure? yes | no

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