Subject: RE: Servovalve Erratic Behavior
Date: Wed, 7 Apr 1999 17:34:48 -0500
From: "Albright, Joe" <Joe.Albright@mts.com>
To: "Chen, Hans" <Hans.Chen@mts.com>, "Anderson, Harlan"
     <Harlan.Anderson@mts.com>
CC: "Gram, Marty" <Marty.Gram@mts.com>, "Saari, Byron"
     <Byron.Saari@mts.com>, "Larson, Rod" <Rod.Larson@mts.com>,
     "Nelson, Terry" <Terry.Nelson@mts.com>, "Melander, Dan"
     <Dan.Melander@mts.com>, "Lorenz, Josh" <Josh.Lorenz@mts.com>

Hi Hans,

Thanks for the feedback.  We tried adjusting the mechanical null last
night.  Electrical null has not been changed.  The mechanical null
change seemed to introduce a level shift in the response, but did not
alleviate the observed dropouts.  Today we changed to a new pilot.  We
are working some software changes but Byron will hopefully trying the
new pilot combination tonight.

Joe A

> -----Original Message-----
> From: Chen, Hans
> Sent: Wednesday, April 07, 1999 3:08 PM
> To:   Albright, Joe; Anderson, Harlan
> Cc:   Gram, Marty; Saari, Byron; Larson, Rod; Nelson, Terry; Melander,
> Dan; Lorenz, Josh
> Subject:      RE: Servovalve Erratic Behavior
>
> Joe, How about moving the servovalve null position (mechanically or
> electrically) and see what happens.  Hans
>
>       -----Original Message-----
>       From:   Albright, Joe
>       Sent:   Wednesday, April 07, 1999 2:44 PM
>       To:     Chen, Hans; Anderson, Harlan
>       Cc:     Gram, Marty; Saari, Byron; Larson, Rod; Nelson, Terry;
> Melander, Dan; Lorenz, Josh
>       Subject:        Servovalve Erratic Behavior
>
>       Hi Hans/Harlan,
>
>       While testing the Toyota Crash Simulator, we believe we are
> seeing short periods of time during a pulse where the 256 spool
> position moves in an unexpected direction for a short distance, and
> then catches back up with the expected position.  It may have been
> doing that for an extended period of time.  We are not certain.  It
> became very evident recently during a higher jerk test because the
> unexplained motion occured right at the time of poppet unseating,
> creating a very large acceleration transient.  I am interested in any
> ideas you (or any of the cc's) might have about why it occurs and how
> to remedy it.
>
>       Byron and I have started investigating possible control output
> errors from the model, and will probably change pilot valves to see if
> it is pilot specific.  One possible explanation proposed was 252 ball
> slop.  If that is indeed the case, an electric feedback pilot valve
> would address that problem.  Along those lines, what is the status of
> the Bosch valve with electric feedback we evaluated a year or so ago.
> Harlan, I was unsuccessful finding it in the back room.  Do we still
> have it, and if so what is the pressure rating on the valve and what
> is required to try it on our system?
>
>       Any ideas anyone would care to share would be greatly
> appreciated.  At the moment, this problem is proving to be a bit of a
> show stopper.
>
>       Thanks!
>
>       Joe A
>
>       joe.albright@mts.com
>       http://intranet.mts.com/users/a/albright/index.htm
>       X4355
>       MIPS Dept (
> http://intranet.mts.com/users/b/bigotB/reference/mips/index.htm )
>       Toyota Crash Sled
> (http://intranet.mts.com/users/a/albright/1997/CrashSim/Checkout/Daily
> Log.htm)
>
>
