Servos twitching and unresponsive

[lenegene]

Hi all,



Everything was working great with our Iridium tracking on the dry run - our ground station was tracking the iridium, but about 45 minutes into the flight our ground station started moving as if it were doing the ‘range of motion test’. It was twitching and slowly panning and tilting in a nonsensical pattern. Even when we disabled the autotrack it continued. ‘Move Antennas to Center’ did nothing, and manual control didn’t work either. We were also unable to control the servos using Pololu, however we only tried using Pololu while the GUI was still open which I have heard may be an issue?



Basically, as long as the servos were powered on, the antennas were stepping through some weird pattern.



We receive an error in the GUI “Unable to Connect to Iridium Database”. We click OK, then update settings and it’s back and connected fine, but could there be some sort of queue building up that the servos are trying to respond to? Could the system have overheated? This isn't the first time this has happened, and last time it corrected itself after shutting everything down and reopening, but not this time. I turned everything on today and it’s working fine, I just would like to know how to deal with this if it happens on eclipse day. Has anyone else had this happen?



Thanks for the help.

[kendra]

We had the twitching and bucking previously (and it totally freaked us out) and when we replaced the cable from the computer to the servos, it stopped.

Also, if I had two varying inputs while the tracker was engaged, for example, I hit Move Antennas to Center while the tracker was going, and it would twitch back and forth.

Kendra

[staley28]

Hello, we are currently having issues with the Twitching Servos towards the direction we are telling it to go on Maestro Control Center.

I have noticed that when we disable the servo dedicated for elevation, the servo dedicated for horizontal directional movement stops the twitching action and will move correctly. If both servos are enabled, then the horizontal servo twitches and the elevation servo is unresponsive. The elevation servos is additionally unresponsive if we disable the other servo.

We have tried replacing the cable from the computer to the servo and tried using an additional computer with no changes in behavior.

Any help would be appreciated.
Thank you,
Derek Staley

[staley28]

We attempted connecting an additional servo to the board in the same spot and had success with moving it with the horizontal servo. At this point, we believe it is either the cable going to the servo from the controller, or the servo itself.