Tricopter wobbles a bit coming down from altitude

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

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • Moderator

    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.

  • 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.

This reply was deleted.

Activity

DIY Robocars via Twitter
RT @SmallpixelCar: My car was able to go all the way autonomously until the crosswalk. It was only 100 yards from the target. What should b…
9 hours ago
Liam left a comment on Agricultural UAVs
"Hi
I'm Liam from T-MOTOR. I would like to reach out to see if there is any possibility for us to work together.
We are a propulsion system manufacturer who offers motors, propellers and ESCs for all kinds of drone applications which vary from secur…"
Wednesday
DIY Robocars via Twitter
RT @SmallpixelCar: Smart move. The car used the shadow to guide it through the bridge. This was never in the training samples. But it learn…
Wednesday
DIY Robocars via Twitter
RT @SmallpixelCar: Getting closer to the target. Single camera. Untrained road. https://t.co/Wsr7RwDamj
Tuesday
Richard Cox left a comment on Australia
"Anyone in the DIYDRONES Australian subgroup based in Alice Springs, NT?
I am experimenting with Ardupilot (standard Arduplane), Pixhawk 4 FC in a 4-ch
RC "AXN Floater Jet" foamy plane..."
Tuesday
Omar Sykes left a comment on Australia
"Hi everyone, I am looking for someone who is good at drone building, repair and software in Adelaide. Please give me a call on 0477 319 219."
Tuesday
DIY Robocars via Twitter
RT @RoboticMasters: #donkeycar https://t.co/czuLoVRcA4
Monday
DIY Robocars via Twitter
https://t.co/DKQbNTbz0g
Monday
DIY Robocars via Twitter
RT @RoboticMasters: Donkey car, car car car car car car; Donkey car, car car car car car car; Donkey Car. Anyone like our tiny tiny donkey…
Monday
DIY Robocars via Twitter
RT @SmallpixelCar: After improving DBSCAN speed, I can get 11 frame per second on @NVIDIAEmbedded Jerson Xavier MAXN mode and the autonomou…
Jun 26
DIY Robocars via Twitter
RT @Heavy02011: Join us at next Virtual Race League: ⁦@diyrobocars⁩ Race #4 - Parking Lot Nerds, August 1st https://t.co/5KUpu7VGaH
Jun 25
DIY Robocars via Twitter
RT @SmallpixelCar: #CUDA implementation should be easy, because most of the time is on distance calculations berween two points and if the…
Jun 25
DIY Robocars via Twitter
RT @SmallpixelCar: This is the view from the car. Even my lanenet inference is fast on @NVIDIAEmbedded Jerson Xavier, DBSCAN clustering tak…
Jun 25
DIY Robocars via Twitter
RT @SmallpixelCar: Ran my car in the park, with single camera and @sparkfun IMU. #TensorRT on @NVIDIAEmbedded Jetson Xavier. Lanenet one fr…
Jun 24
DIY Robocars via Twitter
RT @SmallpixelCar: Making progress on drive the car autonomously in my neighborhood. This run used single camera only. No other sensors. ht…
Jun 24
DIY Robocars via Twitter
RT @chr1sa: The @DIYRobocars/@donkey_car AI racers are getting *fast* in the simulator, in part because it's so well optimized for reinforc…
Jun 21
More…