Digital servo lock-up

I have a project in which I control some hitec digital servos with an Arduino. Digital servos have a failsafe feature in which they go to a predetermined position if they lose signal. If failsafe is set to off, in my understanding, they hold the last position given.

I want to be able to release them completely so that they let go altogether when I'm not using them. In my code I "release" the servos each time when I'm done with them, and that seems to work just fine most of the time but now and then, they grab onto a position and won't let go, until they get the next position assignment and then they keep grabbing on to that. Maybe they get into a mode where they don't hear the release command, I don't know.
It sounds like a programming issue, so I will go back through my code for the nth time and check to make sure they're being released each and every time. BUT, what I'm wondering is does anyone know more about this behavior with digital servos or have similar experience?

I'm using the Hitec 5990 series titanium gear super high torque servos. I'm thinking of going to analog to avoid this type of problem, as analog would work well for me EXCEPT it's hard to find a standard analog servo with the same sort of torque rating and titanium gears. Any information much appreciated - thanks!

Hi,

are you using a separate power supply for the servos ? If not see the two links in my signature for what's happening and how to fix it.

Duane B

Yep they have their own separate power supply with a good sized cap to help out as well.

Does anyone know if using the servo "release" command should completely disconnect the servo? I.e. it's no longer drawing power etc.

Sorry, mean the "detach" command...

"detach()
Description

Detach the Servo variable from its pin. If all Servo variables are detached, then pins 9 and 10 can be used for PWM output with analogWrite(). "

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This makes me think the servo has no idea what's going on, only that it's no longer getting a signal. This would mean that on servo detach, a digital servo would be expected to hold its last position if failsafe is set to "off" or hold its failsafe position if set to "on".

Anyone else's opinions, thoughts or experience around this?