Here is an IMU graph from Flight #7.
According to: http://copter.ardupilot.com/wiki/ac_measuringvibration/
The X-Y (red & green) Acceptable Range is -3~+3. The Z (blue) Acceptable Range is -15 ~ -5. Even ignoring what appear to be "landing spikes" ... all vibrations are beyond acceptable levels.
The following items will be checked:
- Flight Controller mounting location
- Flight Controller mounting material and isolation from airframe
- Propeller Vibration and Balancing
Edit 2015-01: This turned out to be a FAIL. While it doesn't show as good on above graph (as others on this blog) ... X and Y should originate at 0. I think this can only happen when FC's gyro/accelerometer chip is in true middle of quad.
2a. PASSED -
2b. PASSED -
2c. PASSED. Inside the FC, (with it's two-PCB construction) I noticed the grounding metal case of the Micro-USB plug (on upper-PCB) is dangerously close to pins hanging-down from main power-header (from lower-PCB). Added a small piece of electrical-tape (3 layers thick) to prevent a short circuit or arcing.
3. PASSED. Balanced stock-white CX-20 8045 props with Dubro Prop Balancer. They needed little if any balancing so I really doubt they were causing any significant vibrations.
Other things I have done to Nova in this maintenance cycle:
- Did another Accelerometer calibration since FC was moved. Hold quad very still and level/perpendicular at each stage.
- Motor Test via MP/Terminal. They all run and sound ok.
- Upgraded MissionPlanner to v1.3.10 and then to v1.3.11 a few days later
- Set THR_MID parameter to 550.