The last time I posted about my quadrocopter, I was about to have a ton of problems that would keep me from getting it working. That was still in 10th grade. That summer I mostly gave up on the project since I simply couldn’t get it to level properly.
At the end of senior year in high school in AP Physics I had the opportunity to do a physics project instead of taking the final. I had thought many times about revisiting my quadrocopter, but I never got around to it. Even though I didn’t touch it for the better part of 2 years, I was planning ways of making it work and learning new things in school and online.
After spending months and countless hundreds of hours trying to get it to work before, I got my quadrocopter working in a week. All I had to do was cushion the sensor boards from vibrations better and change a few lines of code. At first it didn’t work. Then I tried a vastly different PID tuning and suddenly it started flying reasonably well.
I had gotten so incredibly close to getting it to work years ago. There was just that last little push, along with a much clearer understanding of math, that I needed.
I made a powerpoint presentation for the class that I’m quite proud of. It explains the theoretical implementation behind quadrocopters, but not the practical physical part. I’ll upload a video of me presenting it soon. I also flew the quadrocopter for the class and it worked even better than when I had flown it at home.
Then I flew it more later that day. And I crashed it. I was trying to “bounce” it, by giving it a lot of throttle for a short period of time. Something happened in the software that made it go directly sideways at full power instead of up. It went directly into the side of a jacuzzi (not in the water luckily). At least one of the motors was completely ruined and all of the propellers were smashed and cracked. Luckily the other electronics didn’t seem to be damaged in any way to compromise their ability to work.
I decided to use this as an opportunity to upgrade the motors and propellers. Both of which were ridiculously cheap Chinese parts. Real motors should’ve cost at least $20, but these were only $5. I decided to go for $10 motors this time and real APC (not APC-style) propellers. The old propellers weren’t even APC-style. They were flimsy bendy pieces of plastic that I seriously doubt could effectively support the weight of the quadrocopter.
I’ve barely flown it since upgrading, mostly because I need more battery life and a better charger (the charger was also $5). It seems this motor/prop set is less responsive and uses more battery life. The motor rotors and propellers are much heavier and the propellers are larger in diameter. That equates to a much larger inertia. I think if I re-tune the PID then it will work just fine, and probably be more stable because of the nicer equipment. But right now it is not terribly stable.