Hello everyone. I'm working on my first drone, a 450 size helicopter, using the ArduPilot Mega 2.5+. I got everything assembled and ran a few flight tests to tune the PID's as per the arducopter wiki. It's now flying nicely in stabilize mode after doing the auto trim procedure, so I went up high and tried altitude hold. It immediately went into a crazy tail spin, and I figured it was done. Quickly switched back to stabilize, and it pulled right out. I have allot of available positive pitch, and figure it went to use all of it and the tail just couldn't compensate. So I decreased the amount of usable positive pitch in the configuration tab, and also decreased the values for THR_ACCEL_P to .5 and THR_RATE_P to 4 as, from what I can find, these control how fast it reacts to altitude changes. I went out and tried it again on a fresh battery. It held its heading just fine, and didn't act erratically at all, which was good. However, it just kept climbing. I started at 40 meters (giving myself allot of recovery room, lol), and stopped it when it got to 65. I figured if it were going to come down, it would've done it by then. Position hold seemed to work flawlessly. I saw a little drift with the wind, but didn't have to give any cyclic inputs to keep it in place. I feel like if I get the altitude hold operational, it'll finally be able to fly on full autopilot.
Thanks for the help!
Replies
Interesting thing to note: I went out and tried it in full autopilot. Set a nice quick simple course with a desired altitude of 40 meters. Went into auto at about 50 meters and off it went. It dropped to 40 meters before hitting the first waypoint and stayed almost nose on it the whole time. Then it went into RTL and flew home and began a slow, smooth decent... right onto my car, so I aborted that and landed it manually, lol. It only seems to do it in alt. hold.
Here is the text file with raw data logging. So what exactly are you looking for in there? I can't claim to know what I'm looking at/for in all that data, lol. Would changing the filter from the default 42 Hz to something lower like 20 Hz make a difference? I saw in one of the configuration tutorials that is where most end up of a 450 size heli. Thanks again!
Flight 1 With RAW.log
Hi Nathan,
It sounds to me like your problem with AH is probably due to vibration. How do you have the board mounted?
The best way to check this is to turn on RAW logging, and take it for a test flight, you don't have to actually go into AH. And then attach the logs here so we can see.