Log 10-22-2010

Recalibrated PID for Stable Flight; Successful Tests

Testing the quadrotor has become more ambitious, and we walked around the campus flying the quadrotor. Previous flights had always been conducted very cautiously, at low heights and more or less in-place. Longer and more confident flight was the goal of today's testing, and the quadrotor performed well. It also survived a tumble down a half flight of stairs in the University Center, and tripped over its landing gear to come down upside-down several times. No damage was done to the platform.

Though acrobatic mode works perfectly, stable mode has been wobbly and unsuccessful. We again tied the quadrotor to our parallel bars for anchoring, and recalibrated the PID for stable mode. Here are our new values:

Stable Mode
  • Roll Accel
    • P = 7.00
    • I = 0.00
  • Pitch Accel
    • P = 5.00
    • I = 0.00
  • Roll Rate
    • P = 2.25
    • D = -80.00
  • Pitch Rate
    • P = 2.25
    • D = -60.00

More testing showed that stable mode now works quite well. It does suffer from several problems which will be hard to fix with our current hardware: clockwise yaw drift and position drift. Yaw drift may be a calibration problem, while we hope to get better sensors soon to help us maintain a stable position.

Since much of our testing is done at night, an added LED on the front of the quadrotor makes it far easier to keep track of the direction the quadrotor faces, and to see it easily in darker conditions.

Now that relatively stable flight has been accomplished, our next challenge will be to get the quadrotor to move around on its own, allowing for drifting positioning. We also intend to implement optical flow to aid in localization.