This past week was very productive. We started off facing an issue where one of motors seemed to not be spinning. After some diagnosis we realized that this motor was probably dead from an earlier test where it had smoked up, causing us to have to replace the motor. Then, I changed the formulation of our Kalman Filter based state estimation as Kalman Filters require a prediction step that is very hard to encode for through quadcopter dynamics. Instead, I changed to a Complementary Filter, which is a measurement only approach that combines gyro and accelerometer readings essentially through a linear sum. After some quick tuning, this worked very well. Finally, i added in a safety mechanism where if the throttle stick is set to zero, then regardless of the PID outputs the motors stop spinning. This is necessary to ensure our safety during PID testing.
This week will finally all be PID tuning. We will setup a mechanism by which the drone is hanging from a string, fully unsupported, turn on the drone, and hopefully see if balance as we tune the PID gains. I am a little worried about the little time we have to tune both the pitch and roll gains, considering our interim demo is next week, but I do think it is possible.
I believe I am a bit behind schedule as I was hoping to get to PID tuning last week but because of the motor issue and the reformulation of the Complementary Filter, I wasn’t. That being said, I have set aside this entire week to work on PID tuning for the drone, so I think if I put my head down I can make it work.