My Initial Factory settings:
I recently finished and assembling a QAV540G Quad with low KV high wattage motors with a 6S 5100 Battery pack. It is using TMotors 12" props. The beast weighs about 5.5 lbs.
After assembling, calibrating and setting up flight mode switches, Getting Telemetry going camera gimble, OSD, and the FPV system (1.3 GHZ, relaying to 5.8GHZ at the ground station). and a few just off the floor hoovers, I decided to take it up outdoors.
The first flight with no PID changes, it flew very stabile and handled pretty good although it feels a little heavy.. after climbing to about 40 feet I switched it into loiter, and it hovered "hands off" pretty good..
The second test flight was the next day in about a 15 MPH wind.. I was near a building that was blocking the wind, but when I got up high, it still seemed pretty stable even in the wind. However, I switched into Loiter, and it started rocking, seemed to be oscillating back and forth and with each oscillation, it got wilder and wilder, until I switched it back to stable mode. It recovered and I brought it back to a landing without incident.
I don't understand much about the PIDS and adjusting them, but with the little info I have, I decided to take a stab at it. I reasoned that the lotier p value needed to be lowered due to reading somewhere that for more powerful motors the P values might need to be reduce. Since loiter mode was where the issue was, I decided to try reducing the P value. (and I value)
I changed loiter P from the default value of 1.000 to .600 and I changed the I value from the default of .500 to .300
After this I flew it again, and in a slightly higher wind. It didn't oscillate but did seem to break out of a tight hold to climb or drop a little, but only a limited amount, and then seem to work its way back to the holding position. Also, I noticed that when I gave it what I thought was rudder input only , it climbed or dropped a little.
What should my next adjustment be, split the difference? or should I start over with a different approach?
Replies
Hi Richard,
Did you get any further with PIDs for this copter. I am trying to get mine done now.
Scott
providing your quad is able to fly with the stock PID setting (I had to lower mine abit) and you can switch to alt hold with successful results you can then use autotune which you can setup with a switch on ch7.
Hi Daniel. Have you tried it on a heavy lift copter? I tried it and crashed. Not really a fault of Auto Tune, but Auto tune, as per the docs, uses a lot of input, and can cause sync issues on low KV motors. The docs don't actually say not to use it for low KV motors, but do warn with a nice demonstration video. I suspect my oscillation while in auto tune got too large to correct quickly and one of the motors momentarily stopped tipping it over into and down into a tree before I could recover. Fortunately no damage. Trying to find someone who has experience with auto tune on low KV (100) motors.
Hi Scott! If you find anything out, please let me know! I too am trying to find out this information before I put my 20lbs system with 100kv motors and 28 inch props through autotune...
Good evening. I have had a good day. Lots of tuning. Seems now (no wind yet) very stable in all modes except Loiter. I am going to put together a page with logs, pictures etc in the next few days. I will make sure it gets linked here.
Had some success - results updated here: http://diydrones.com/forum/topics/my-heavy-lift-u8-pixhawk-sweep-he...
This helped me understand how these settings work. An intuitive understanding is very helpful in adjusting pid settings.
http://www.pidcontrol.net/
I dont recommend you buy the book their selling as its for engineering types, however, the email 5 day email explanation explains the conceps in a simple intuitive mannor that will really help.
Hi Scott, my quad is a 500mm with 950kv motors, 20a esc, running a 2800 3s and FPV gear (no gimbal)
flight weight is about 1.2kg, Its a little under powered but holds alt with full pitch or roll. So I guess its in a different ballpark from your quad.
how did the quad crash? if your setup is overpowdered you might need to lower your Throttle Accel PID gains.
Yes I think it is over powered - thanks I will try that. Not sure about sync - logs are up on my forum post. I added 4 kg (total of 11.2kg AUW) for a test - 50% throttle only which is good, but still oscillated (less though) - need to play some more. One suggestion was to increase D - going to try that today. Thanks heaps.
this is the info I found on adjusting that correctly.
check alt tuning here http://copter.ardupilot.com/wiki/tuning/
Regards Daniel.
also increase D in very small amounts i.e: 0.001 at a time.
-
1
-
2
of 2 Next