David Minkler wrote:
<snip>

> My brain stops sending signals all the time, just ask my wife.  :-)
>
>  From your initial description:
>
> "Muscle 1 gets 20khz, 10vpp centered on 0v.  To move it from neutral, the
amplitude of the 20khz signal drops to say 5vpp or rises to 15vpp."
>
> it sounds like the actuator is centered or neutral at an input signal
> amplitude of 10Vp-p (for example), extends or servos to a new position
> (again, for example) at an input signal amplitude of 15Vp-p and
> contracts with a 5Vp-p signal.  If the input signal at the actuator
> drops to 0Vp-p, as would occur if the controller stops sending then the
> system servos to a super contracted state (on all channels!).
>
> Most of the digital signalling systems that I'm aware of either hold the
> last commanded position or go into some kind of pre-programmed sequence.
>
<snip>

Yeah it was an error in the initial description.  Whoops! You are correct, I
guess I'd have to rectify the signal before smoothing, or else it would
always cancel to 0v for a symmetric sine wave centered about 0v.  So then
for a rectified 0v indeed it would swing to one extreme, as you stated.
Hows that for a graceful failure mode? :>

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