Guardian 2D/3D servo jitter problem - RC Groups
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Feb 05, 2013, 03:53 PM
Registered User

Guardian 2D/3D servo jitter problem

I am experiencing some strange servo jitter behavior when control sticks are moved close to neutral position. It doesn't matter if the Guardian is in 2D,3D or even stabilizing off mode. As long as I pass the servo signal from my receiver through the Guardian, servo movement is not smooth for input signals close to neutral. The jitter also affects other channels than the one currently being moved, though not as much as the channel with the moving input.
With slow servos (cheap no-name brand) the effect is hardly noticeable but with fast digital servos the jitter makes me to worried to fly with.
It seems to have to do only with the Guardian reading of input from the receiver as I can only get the jitter by moving the sticks and can not see it for servo movements caused only by the stabilizing.
I'm using a Futaba 2.4ghz system and tried two different receiver types (FASST and FASSTest) and various servos. Without the Guardian connected all other combinations moves smooth also close to center, but with the Guardian connected the jitter happens even if it is in non stabilizing mode.
Any ideas of what is causing my problem or how I can solve it?
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Feb 07, 2013, 04:31 PM
billpa's Avatar
Hi, and sorry to hear about your jitter issue. We're looking into your report, and I'll get back soon.
Feb 11, 2013, 04:18 PM
billpa's Avatar
Hi, we have been discussing your report here - sorry for delay.

With stabilization disabled, is it possible for you to trim your sticks to a point where the jitter happens without needing to move your sticks to reproduce it?

Also, could you let me know the model number(s) of the receivers you are using?

Finally, if convenient, could you make a short video of the servo movement (with audio) and post it on youtube for us? That would help us to understand better the exact type of jitter you are seeing.
Feb 12, 2013, 02:38 PM
Registered User
Here is a video of a test:
Guardian servo jitter problem (1 min 6 sec)

At first smooth movement from the guardian gyro. Then I set it in gyro off mode to just pass through input signal. Moving input close to center is not smooth (it is without the guardian connected).
Servo in this test: futaba S3001
Receiver: futaba R6106HFC 2.4Ghz FASST

I'm not able to set a static input that results in any jitter. It only happens at movement.
It's like input close to center doesn't update the servo position at all and then when input is outside some threshold the servo suddenly catches up with some additional jittery movement.
The servo is not a digital one as the only digital one I have are currently glued in place in my airplane. The digital ones makes it a bit more noticeable. Mainly because they are just responding faster I assume.
Last edited by SebbeMalm; Feb 12, 2013 at 02:40 PM. Reason: More details
Feb 14, 2013, 03:06 PM
billpa's Avatar

First, thanks for taking the time to set up this repro and video. That makes it very easy to see the issue.

We've been discussing this here and have a couple of theories. If it's convenient, would you be able to try one more test to help us confirm? Assuming the issue happens also with your aileron channel (I believe your demonstration shows the elevator channel) could you disconnect all the cables from your Guardian to receiver except the Aileron, and see if the issue recurs? If it does not, could you add back the channels sequentially, until it reproduces?
Feb 17, 2013, 02:32 PM
Registered User
I've been testing some more and found some interesting results. As you anticipated the number of connected channels has an affect. With only aileron connected (that is also no gain, no mode) I'm not able to reproduce it. However by connecting any other input its back. Also with only adding the mode switch the problem is there also for the ailerons.
What I also found was that the jitter happens when two (or more) input channels are at the same value. With only aileron and mod connected I can move the position the jitter happens by changing the center value of the mod input, of corse if I move it to much I also change the mode.
Feb 18, 2013, 07:34 PM
billpa's Avatar
Hi, and thanks for taking the time!

We've ordered a similar Futaba setup to attempt to reproduce the problem here and get it addressed.
Jun 12, 2013, 03:31 PM
Registered User
It's been a while. Any progress on this issue?
Jun 14, 2013, 04:08 PM
billpa's Avatar
Hi, and sorry for delay. We have not been able to reproduce this problem here, unfortunately. We're going to continue to try, however.
Jun 04, 2014, 10:13 PM
Jon Cammarata
Has this been resolved? I have same exact problem except I am using all digital servos and the radio is modded for er9x with an frsky dht-u transmitter module. Before adding guardian everthing was smooth and perfect. Now servos jump and jitter arround center point. Ive tried raising and lowering the frequency in transmitter and on guardian. Nothing changes. When the 50cc motor is running the plane tries to roll left as rpm increases. Higher rpm means higher rate of roll. The roll issue does not happen in off mode. Servo jitter is in all modes. All this was noticed on ground so i did not fly.
Jun 05, 2014, 06:22 AM
A man with too many toys
I think that one problem is that the guardian has a lower bit resolution than most modern radio systems. I am looking forward to the Guardian V2.

Jun 09, 2014, 05:50 PM
Jon Cammarata

Would decreasing the frequency

If I turned my transmitter down to, say, 350milsecs, would that help? I wish I was near my toys so I could try. The guardian can be turned up to 400milsec output for high end servos. My servos are all capable of listening to over 400 but when I set the output to 400 my aileron and elevator didn't like it so I turned it down to 150 from the guardian but I left my radio where it was. 850ms, I think. I thought maybe the Direct Rate was the issue, but it sounds like Direct Rate is not active when both modes are off. Is this true? Or, am I mistaken? Is Direct rate still active when the mode switch is in center (off) position?

I Guess customer support doesn't monitor old threads.
Jun 10, 2014, 07:29 AM
JohnET's Avatar

If you are still having an issue with this, can you please open a support ticket on our website?

Regards, John
Jul 25, 2014, 12:28 AM
Registered User

twitching of Right Aileron Servo

I have this same issue of the twitching servo that increases excessively as further servos are connected.
I submitted a support ticket. I hope there's a workaround that Eagletree can provide. Radian Pro is grounded.

Aircraft: Eflite Radian Pro PnP with digital servos
Transmitter: Futaba 7Ch H/S
Receiver: Futaba R617S 2.4 Ghz FASST Receiver

Eagletree product: Guardian 2D/3D Stabilizer

The issue I am having is the same as the below entry on the RC Groups Forum for Eagletree made by Sebbemalm (Guardian User) on 2/17/13 to Eagletree Technician, BillPa.
The issue I've observed is the same where after all leads are installed and the plane powered up, the right Aileron servo twitches excessively. Disconnect the Guadian and connect direct to the receiver - everything's fine. Reconnect to the Guardian, problem comes back.
I disconnected everything and started all over from the throttle connected to the receiver, then I installed the Ailerons on a "Y" harness. at this point the Ailerons work as they should and the Guardian responds. Then I add the elevator...all fine. Then I add the is where the twitching (excessive) begins and even accelerates in movement - almost aggressively. At this point i have to disconnect the power cause it seems like the connection with the Guardin is about to break the control surfaces off.
Jul 29, 2014, 02:30 PM
Registered User

Same jitter issue

Im flying a Tricopter reversed setup on my vector and i am experiencing the exact same problem on the yaw servo. When sticks are cloe to center i can hover but as soon as i move the yaw stick it comes out of controle and i have hard time getting it safely down.

Any solutions?
Last edited by kork123; Jul 29, 2014 at 02:36 PM.

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