CALendar Pal
This is an old project and I no longer have the code
Along with two other students, I created this robot as a final project for a class on designing for the Internet of Things. This time lapse was captured as part of our presentation.
There are a couple of steps to the operation of the robot:
Fetch events using the Google Calendar API and parse the relevant data in Python
Convert strings of characters into coordinates on the board based on a custom font
Compute the inverse kinematics to find the necessary positions for each stepper motor
Send these positions over MQTT to the board and execute on the physical device
There were a couple of interesting points in the development of the robot. The first was related to using the Calendar API on the microcontroller. We kept running into permissions errors when trying to access the events with a request from the board. When submitting these from a laptop, there were no problems. To get the robot working for our presentation, we decided to compute the coordinates on the laptop and send these to the board via MQTT, a protocol we had worked with earlier in the class. With more time, we would have liked to get the API requests working on the board to eliminate the need for another device.
The second was about how to communicate when the pen should be on or off the whiteboard. Ideally, this information is conveyed as part of the coordinates for each letter. Doing it in this way eliminates the need to send a second stream of data to the microcontroller. The coordinates for each letter need to be scaled and shifted, so the pen commands need to remain unchanged under these operations. NaN is a natural choice for this: incorporate NaN’s into the font as toggle commands for the pen, and then during operation keep track of whether the pen should be on or off.
