My tricopter flies great, as in really great.  I do have a question about coming down from altitude.  When I cut the power down (in stabilize mode) to ¼ throttle or so, the tricopter tends to wobble a bit and I can hear the motors trying to stabilize the aircraft during decent. 

The APM2.6 is doing its job of keeping the system pretty level, but it does often get shaky until I apply power again.  If I cut power very slowly it will come down slowly and more evenly, but if I want to come down fairly rapidly, it will wobble a bit.  Is this fairly common?  I certainly wouldn’t just chop the throttle, but it seems like it ought to come down without getting a bit wobbly.  Any ideas?  Thanks, james

Views: 642

Reply to This

Replies to This Discussion

I had the same issue on my hexa in stabilize. Going down faster = faster woobles. Down slowly ok. I some circumstances, it was even impossible to regain stable flight when the copter was too low after fast descent and I had a minor crash (4 props,a motor base plate, some gimbal alu arms). All repaired in two days though.

I lowered the I term in the PID a tad in Rate Roll and Rate Pitch (I think it was from 0.020 to 0.018; don't remember if also in Rate Yaw or not) and tested different descent speed: everything's fine.
Worth a try.

Problem with rotor craft is that while descending your props go through their own highly turbulent downwash causing the wobble, increasing the Rate_I term (which corrects errors over time) usually helps.

I have my Rate_I set to double the P value which also makes the craft very stable and firm in flight, with a low 'I' term if you had to hang a weight on one arm the craft will tilt in that direction, with a high 'I' term it will attempt to correct for the weight and keep flying level so it helps for CG errors too.

Otherwise fly forward while descending so the props descend ahead of their downwash.

Thank you both very much!  I should have added that the downwash is exactly what I expect is going on, because when I am flying forward and drop at a high decent rate, the wobble is not present.

I have not adjusted any of the settings yet, because I am so stoked about how well it flies right out of the box.  But I am going to play with the values now for sure.  It is simply amazing!  My first weeks were using a Bixler airplane and I planned missions where it flew a pattern and landed on our runway to the amazement of everyone at the field.  I shut off my Futaba and it circled overhead.  All incredible.  In case you can't tell, I am still jumping up and down at how cool this is!

Thanks again,

James

Great stuff, it's nice to see such enthusiasm, enjoy the journey!

Reply to Discussion

RSS

Groups

Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service