That is fine if you are designing from scratch and can program the
controller for PWM to run the motor faster in one direction than the
other but for a home brew match up it would be close to impossible.

Bruce in Alaska wrote:

In article k9elb.83730$sp2.44153@lakeread04,
Glenn Ashmore wrote:


Regular single ended double action cylinders have less
displacement on the rod side because of the volume of the rod. With a
constant pump speed it retracts faster than it extends and with less
force. You would never get an autopilot logic unit to control it properly.


The above is NOT a correct statement considering that most AutoPilots use
an Electonic Feedback Loop for Rudder Position. This is accomplished by
having a Rudder Position Encoder mounted to the Rudder System that then
feeds back to the Pilot Logic directly. In this type of system, the
travel time of the Piston isn't even considered, unless the Hydrolic
Pump that feeds the system is so underrated that the movement of the
piston is slower than the Pulsewidth Modulation of the Feedback Loop.
All the AutoPilot OEM's I am familiar with take this into account when
designing the Feedback Loop in the first place, and therefor it is a
NONISSUE for the end user.

Bruce in alaska

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

In article XDElb.87781$sp2.47416@lakeread04,
Glenn Ashmore wrote:

That is fine if you are designing from scratch and can program the
controller for PWM to run the motor faster in one direction than the
other but for a home brew match up it would be close to impossible.

Bruce in Alaska wrote:

In article k9elb.83730$sp2.44153@lakeread04,
Glenn Ashmore wrote:


Regular single ended double action cylinders have less
displacement on the rod side because of the volume of the rod. With a
constant pump speed it retracts faster than it extends and with less
force. You would never get an autopilot logic unit to control it properly.


The above is NOT a correct statement considering that most AutoPilots use
an Electonic Feedback Loop for Rudder Position. This is accomplished by
having a Rudder Position Encoder mounted to the Rudder System that then
feeds back to the Pilot Logic directly. In this type of system, the
travel time of the Piston isn't even considered, unless the Hydrolic
Pump that feeds the system is so underrated that the movement of the
piston is slower than the Pulsewidth Modulation of the Feedback Loop.
All the AutoPilot OEM's I am familiar with take this into account when
designing the Feedback Loop in the first place, and therefor it is a
NONISSUE for the end user.

Bruce in alaska

You missed the point entirely with the above. The PWM for the rudder
position is set in the controller design and does not care what mechanism
is moving the rudder, andlong as it has postive control over that
mechanism. (ie move right, oir move left) The rest is already designed
into the controller feedback loop, and a nonissue for the user. It
could be an issue if you were designing an AP controller from scratch,
but that is not the case in this thread.

Bruce in alaska
--
add a 2 before @

Bruce in Alaska wrote:

You missed the point entirely with the above. The PWM for the rudder
position is set in the controller design and does not care what mechanism
is moving the rudder, andlong as it has postive control over that
mechanism. (ie move right, oir move left) The rest is already designed
into the controller feedback loop, and a nonissue for the user. It
could be an issue if you were designing an AP controller from scratch,
but that is not the case in this thread.

Unfortunately that IS the case. He wants to control the drive from a
simple tiller pilot output. That is just forward and reverse. No PWM,
no braking, no rudder angle input, no fancy logic. I don't see a way to
do it in the first place but a balanced double ended cylinder will make
what ever solution he comes up with a whole lot simpler.

-
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com