Hi all,
I have finally put a Tri-Copter together in an attempt to get Tri's up to the same level of performance as the more common quad, Y6, X8, Hex and Octo. This is what I have put together:
based on these Hobbyking parts:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=66417
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14458
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=65156
The tricopter has tuned up reasonably well using autotune and I feel happy with the performance so far. I didn't find the initial setup much more complicated compared to normal quad. I did find the first flight much more nerve racking because of the poor yaw performance during take off. I am interested to see if my confidence in the yaw performance improves now I have a reasonable yaw tune.
I am looking for feedback on what issues Tri-Copter pilots are having with Arducopter. Some of the issues I see are:
1. Dynamics of having the rear motor and propeller CG above the pivot point causes the opposite rotation to the thrust.
2. Roll, pitch, yaw and lift coupling potentially causing issues with auto-tune.
3. The frame type needs a stability patch to prioritize motor output.
4. There is no thrust adjustment on the rear motor based on angle.
5. Yaw auto-tune could be made more efficient by removing any D term or filter frequency tuning and going directly to Rate P tuning.
6. There may be improved motor mixing that does a better job at isolating the 4 control axis.
So let me know what you think I should be looking at that is particularly relevant to Tri-Copters.
Replies
Hi Patrick,
It would be great if you could add a couple of pictures of your Tri. I suspect that some of this ringing may be unavoidable if the CG of the rear motor and prop is above the pivot point. So I am interested to get photos or accurate descriptions of Tri's along with the problems people are seeing.
Thanks!!
The rear definitely is high; it would be interesting to pull it down via an adapter bracket to see what that does.
Thanks Patrick!
What do you think of the tough tilt?
Which servo are you using? I've seen the same copter wag and not wag just by changing a servo. One of the biggest problems with tri-es is servo play. Are you ale to move yor rear motor even 1-2degrees before the servo counteraction kicks in? If yes, you need a new servo. Try getting a quicker servo rather than stronger (as lon as it has more than 2kg for your frame) i mean a helicopter tail quick servo under 0.05s.
Also, if you downgrade to 3.1.5 do you still have the yaw wag?
I am using an ES3154. Seems pretty nice, but yeah it does have 'some' play. It does make sense that would impact wag especially when otherwise stationary.
I haven't run 3.1.5 but I so recall it with 3.2.1 (it's running 3.3 rc9 now).
I am using this one, though my tilt is considerably different than yours:
tilt1.jpg
tilt3.jpg
tilt2.jpg