Introduction: Around the World (Smart Globe)
This project was created for the MIT course, Intro to Making (15.351). Our project, titled “Around the World”, is a smart globe that responds to a user entering a city into a terminal. Once a city is entered, the globe spins on a motor attached to its base to reach the longitude of that city. Then, a laser attached to a rod inside the globe is angled by a motor to point to the correct latitude for the city. With these two motors, the laser points at the city entered by the user. The globe is translucent enough such that the laser mounted inside of it can be perceived by the user. We were inspired by our team member Alex’s passion for globes, as well as our desire to surprise users by transforming a commonplace object into something engaging and “smart”.
Pre-made supplies to purchase
- 1 12-inch globe, semi-translucent such that an internal laser can shine through (we used this)
- 1 step motor for base of globe (we used this)
- 1 step motor for internal laser (we used this)
- 1 laser (we used KY-008 Laser Dot Diode)
- Power Supply (we used this)
- Motor Drive Controller Boards for Arduino (we used this)
- Wifi chip (we used NodeMCU 1.0)
Parts to make
- 1 3D-printed rod to suspend internal laser/motor from top of globe (see attached STL file)
- 1 3D-printed attachment to attach internal motor to laser (see attached STL file)
- 1 3D-printed attachment to attach base motor to globe (see attached STL file)
- Base for final assembly
Step 1: Procurement
Our first step was to procure materials for the project. While we knew that our required materials list could change as we got further into developing our project, we ordered the supplies as soon as possible to avoid delays to the project. We were able to obtain all materials either through Amazon or from MIT Protoworks. We ordered all parts in our supply list at this time. However, the key part that we needed to obtain early was the globe, as the dimensions of all of our other parts, as well as the design for final assembly, depended on the size and features of the globe. We also needed to ensure that the laser we purchased was bright enough to shine through the globe, since the laser would be mounted inside of the globe.
Step 2: Sketching
After selecting our project, we sketched different ideas of how the components could work together, to ensure that we had a full idea of what parts we would need to buy or build. We started by sketching the overall mechanism and how each part would be connected to the overall assembly. Then, we divided up into smaller teams, with each person responsible for one or more parts. We sketched and identified the necessary dimensions of each part, based on the size of the globe and motors that we purchased.
Step 3: Software
While some of us were focusing on sketching hardware components, others focused on the software. We first had to do the calculations to convert a single degree of latitude and longitude to a specific number of steps on our motors, based on the size of the globe and the total number of steps in our motor.
We relied on the Google Maps API to help us convert a city (entered by a user) into latitudinal and longitudinal coordinates. Once we had these coordinates, we wrote code that would instruct the motors, through an Arduino, to turn a certain number of steps based on the coordinates obtained by the API.
Step 4: Hardware
After we had sketched the components that needed to be 3D printed, we designed them in CAD software (OnShape). We 3D-printed each part and tested it within its sub-assembly to ensure that it fit as intended.
Step 5: Final Assembly
After iterating on the software and hardware until we were satisfied with each component, we assembled the final product. In addition to attaching the motors, lasers, and electronics to the globe, we built a base for the final product to sit on.