Hello everyone, my name is Sasha, I am a rising senior at School of the Future. During my time at BlueStamp I built a MintyBoost as my starter project and a robotic arm as my main project.[Photo of final project here]
My Robotic Arm
Since the start of my application process for the program I knew I wanted to do something that would be both challenging and exciting. There were a lot of projects that fit these criteria, however, one really stood out to me: the robotic arm. I had considered the RC tank and the omnidirectional robot however, I realized I could just buy one easily from a toy store. A robotic arm, on the other hand, that was something you don’t see at a toy store.
Despite the apparent difficulty I originally thought that the project was going to be easy. While I had only minimal experience with coding and building electronics I was confident that it wouldn’t take more than a few weeks at most-I was wrong.
The first week of six, I was unable to do any coding whatsoever due to having an extremely old mac computer (I think it was from 2006). I spent most of the week trying to get the software I needed working. That isn’t to say I got no work done. I had begun of the electrical aspects of my project, wiring the servos and potentiometers that I was using to my Arduino. The next week I got a new laptop and the real fun began.
While all of the program was fun, the part I enjoyed most was coding. When my first idea of using potentiometers to control the servos did not work, I turned towards controlling them by pure code. I decided to write a code that would allow me to operate my arm straight from my keyboard. In order to accomplish this, I used a combination of “C” the code that the Arduino runs on, and a separate coding language called Processing. I wrote a sketch in this language that would read when a key was pressed and then write that key in the serial monitor of the Arduino. The code I wrote for the Arduino would then read the serial port automatically and move one of my servos accordingly. While I could control my arm using just the Arduino code I had at this point, I would have to press enter after each key which would severely hamper my arm’s efficiency by making it take a long time to operate. When I add the Processing sketch, I can control the arm in real time straight from my computer. At the moment, my arm needs to be pluged into my computer. In the future I hope to make the arm wireless as well as add a rotating base that would allow me a third axis of motion.
The starter project that I chose was the MintyBoost. It is a portable cellphone charger that runs on AA batteries. The power source is a battery pack with 2 AA batteries that provide an output of 3V, however, the charger needs an output of 5V to work. In order to get this 5V output, I used a boost converter circuit. This consists of an inductor that resists the change in current when the transistor is deactivated by the LT1302, a chip that deactivates the transistor when it senses voltage in excess of 5V, and supplies current through a diode (a component that only allows electricity to flow in one direction) to a capacitor that stores voltage up to 5V. When the inductor can no longer supply current, the capacitor discharges the stored voltage into the USB that transfers it to the phone. As the capacitor is drained the voltage drops resulting in the reactivation of the transistor which recharges the inductor and starts the process over.
Looking back on my experience at BlueStamp, I can certainly say that it was both a wonderful learning experience and a wonderful time. I met so many interesting people, students and instructors alike, that made me even more interested in the field of engineering. Before the program I knew I was interested in engineering but now I can truly see doing it as a career. My only regret is that I will not be able to come next summer as the program is only for high school students.
Bill of materials:
http://bluestampengineering.com/wp-content/uploads/2011/08/Mechanical-Drawings1.zip (Credit goes to Ariel, a BlueStamp student from a previous year)