Well, it was not exactly the real maiden as I did a bit hovering in the yard before but it was the first "real" flight in open area.
Setup:
- MF450 frame from eBay (also available from BEVRC)
- 4xTurnigy NTM28-30s 800kv (short shaft)
- RCTimer noname 10x45 props (BIG pack :D )
- Zippy compact 5000mAh 4S LiPo
- APM 2.5 / ArduCopter 2.91b
- Hobby King Wing Camera mounted on sixfold stacked double-sided foam tape
The quad is yet untuned. From my perspective, it looked pretty stable in the air with the default settings when I was hovering. From close up, I noticed constant small fast oscillation in pitch and roll which also show pretty clearly in the video. On the maiden itself, I noticed mainly huge problems with altitude hold. The copter would lose altitude over rather short time and generally be not very precise, as can be seen. Additionally, when switching to alt hold (I put alt hold to an override toggle switch), all motors go low, almost off for a sec and then spin up high. VERY scary, seeing the quad falling a foot or so after switching...
Now, about tuning. I have read around and I don't fully understand the tuning procedure yet. Well, physics class is 20-something years ago :). One issue is also that this little thing has amazing power and I don't feel comfortable holding it in my hand while tuning. I tried once shortly but when I tuned the RATE_P up with CH6, the motors suddenly spun very high and I almost let go, so no joy there.
I was hoping that somebody might have a similar setup and somebody could generally give some advice what do do about the fast oscillations and the alt hold problem. Right - forgot - it was a bit windy today. Wind was between about 0 and 2.5m/s.
My goal is to have a rather conventionally (read: boring) tuned quad for video and photo purposes. No aerobatics or wild FPV chases intended. Just mostly slow and stable flying and hovering.
Comments
Yes, it crashed a few times before from very low altitudes on grass when I did the first tests. The props were balanced. I'll try to take a video from my perspective. The vibrations are relatively fast and small roll oscillations. It looks like a beginner circus artist practising balancing on a ball. On alt hold it's much stronger than on stab. In the video you can actually hear the motors oscillate.
Did you ever crash this quad before this video? Or did you crash those motors previous?. It looks rather unstable for me. Those vibrations you have I don't believe are related to tune PID. Did you ballance the props?
Actually, I have no idea what's the AUW. I don't have any kind of scale. That's on my shopping list. My guess from the parts list would be something between 1000 and 1200g, maybe a bit less.
I just returned from another test flight. The oscillations are there in STAB mode but in ALTH they are pretty extreme, easily spotted from the ground. In STAB they are not so easily spotted but show on the video.
Rates following. The only thing I changed was the THR_ALT_P after the maiden. It was by default on 2 and I changed it to 3 because the info in MP says minimum value is 3.
RATE_PIT_D,0.004
RATE_PIT_I,0.1
RATE_PIT_IMAX,500
RATE_PIT_P,0.125
RATE_RLL_D,0.004
RATE_RLL_I,0.1
RATE_RLL_IMAX,500
RATE_RLL_P,0.125
RATE_YAW_D,0
RATE_YAW_I,0.015
RATE_YAW_IMAX,800
RATE_YAW_P,0.2
THR_ACC_ENABLE,1
THR_ACCEL_D,0
THR_ACCEL_I,1.5
THR_ACCEL_IMAX,500
THR_ACCEL_P,0.75
THR_ALT_I,0
THR_ALT_IMAX,300
THR_ALT_P,3
THR_MAX,1000
THR_MID,500
THR_MIN,130
THR_RATE_D,0.2
THR_RATE_I,0
THR_RATE_IMAX,300
THR_RATE_P,6
What is the total AUW weight of your quad ?
What are the values of your P,I,D for rate_roll and rate_pitch ?