Hey guys,
I made a video that explains what is going on. You can see it below. Be warned that its loud.
VIDEO EXPLAINATION:
TEXT VERSON:
Basically what is happeneing is I have my quad tethered to a stand with some rubber cords. When I take off the gyros all read level. After about 20 seconds I start getting some funky readings and then upside down completely. I have calibrated my ESCs a few times. Not sure whats up.. ANy help would be great.
Riley
Replies
On a side note: This would be a great video to post as an example of aliasing and how being outside the proverbial "vibration noise range" will cause your solution to blow up.
Yes, this is the accelerometers getting too much vibration. They respond to a high frequency and the sample rate causes
"aliasing" which makes the DCM to slowly tilt. If you balance the props and get rid of the hard coupling of the frame to the APM you will also see much better performance.
Jason
Have you done hand testing yet? Did you go thru the wiki? http://code.google.com/p/arducopter/wiki/AC2_Preflight
If your quad hand tests ok then take it out and fly it! It will put a huge smile on your face when its up in the air!
I *think* it is your accelerometers providing erratic movement input to the INS solution, resulting in 'attitude creep'
But I'm pretty much making that up as an educated guess, as I've never run mine without some type of vibration isolation, and I've never seen mine do what yours shows in the video.
I do not use elastic cords for tethering, the produce strange results. But I do not think that they are the cause of the odd gyro results. Listen to Jason, he knows. I use a $0.99 foam pad from Michaels Art Supply that I cut up into tiny bits and I mount the APM with six zip ties (one passing through the frame, then some foam, then the APM, then some foam) and put just the head of another zip tie on the other side, and cutting off the excess. I have some photos from my most recent 3DR build, if you are interested. It works very well, and is very cheap. It might throw off your spacing of your beautifully crafted frame.
Vibration is your accelerometer's worse enemy, and it cannot be good for your gyros either. You are setup for the proper x vs + based on your configuration, right?
Did you solder your Filter Pads? Also, Try and mount the APM on some foam to absorb some of the vibrations.
Jason