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Author Topic: Hydraulic engine controled by mach3  (Read 1201 times)

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Hydraulic engine controled by mach3
« on: June 11, 2016, 09:08:12 AM »
Hi to all, I was thinking if there is a posibility that mach3 can control an hydraulic engine with an encoder, I never saw sometging like this.
if someone can help me I will be soo happy.

Thanks to all

Pablo.
Re: Hydraulic engine controled by mach3
« Reply #1 on: June 11, 2016, 08:02:43 PM »
Hi Pablo,
how does your hydraulic engine work? The type I'm most familiar with are controlled with a valve which
allows fluid to pass in one direction for CW and the other direction for CCW and blocks all flow for
no rotation.
Depending on the size of the hydraulic motor the valves required are pretty big and electrically
operated valves are pretty expensive. If you have the required valving the Mach could probably
be induced to read an encoder and control the valves. Mach can 'close' a servo loop but it is
not its primary function.
The vast majority of posts on this forum use Mach as a step/direction generator to a dedicated
motor controller and it is the motor controller which closes the loop.

Craig
My wife left with my best friend...
     and I miss him!
Re: Hydraulic engine controled by mach3
« Reply #2 on: June 26, 2016, 03:44:17 PM »
The vast majority of posts on this forum use Mach as a step/direction generator to a dedicated
motor controller and it is the motor controller which closes the loop.

Craig,
Standard stepper drivers output power in a way that turns the stepper incrementally but if the stepper jams the drivers keep going, there is no feedback, the loop is still open,
Regards,
Nick
Re: Hydraulic engine controled by mach3
« Reply #3 on: June 27, 2016, 03:51:26 AM »
Hi Nick,
quite so, the vast majority of steppers we use work that way and quite adequately mostly. Servos do require
a closed loop however and the only practical way to do that is with a servo drive with feedback.

Pablo's question was about a hydraulic motor with an encoder. Mach could quite easily read the encoder and
decide for instance whether the motor is required to rotate CW or CCW or within some deadzone not rotate at
all. The problem is how Mach could communicate to the motor or rather the electrovalves to achieve the rotation.

Mach's native communication is step/direction. Maybe you could use the direction signal to direct the sense of rotation.
That does not however give the motor enuf info as to when to stop so that it matches the commanded move.

Maybe you could write some code which controls the valves so that say one valve remains open until such time
as the encoder ticks equals the step ticks. The hydraulic motor could then achieve position control but not
velocity control. Linearly coordinated moves would not be possible even if two axes eventually ended up at
the right location. Maybe Pablo's application would accept that limitation.

The other way would require some sort of electronic drive which accepts step/direction and compares that internally
to the encoder, ie a feedback servo drive by any other name. I have seen references to hydraulic servos but never
read any of them. Apparently they were popular in the 50's and 60's when CNC was in its infancy. Pressbrakes and
benders must use some hydraulic system.... maybe Pablo can look in that direction for ideas.

Craig
My wife left with my best friend...
     and I miss him!