Electrical solution for cylinder synchronization

I have a machine with 4 parallel cylinders moving a structure. I read about hydraulic solutions that are available for synchronizing cylinder position.I am following the electronic synchronization idea because I was told it is more precise and might be cheaper.

For now, I am searching for an electronic solution which might help us to synchronize the position for 4 cylinders electronically. each cylinder has a built-in analog transducer and a proportional valve. Does anyone have a suggestion for me?

Always the synchronization of hydraulic cylinders has been a difficult task and I agree that in many cases, synchronization with position transducers may be the best system.
But it is even more important how the hydraulic circuit will be, especially in the safety aspect.
Obviously, it is necessary to follow all the regulations applicable in your country, since the person who designs lifting systems also assumes responsibilities.

In the regulation aspect, your PLC should have the appropriate input and output cards for your transducers and proportional valves.

What I did in similar case was to generate an ascending or descending position setpoint ramp, and then the proportional valves are regulated by four PID loops

I/we make hydraulic servo controllers.

Prince said:

I have a machine with 4 parallel cylinders moving a structure. I read about hydraulic solutions that are available for synchronizing cylinder position.I am following the electronic synchronization idea because I was told it is more precise and might be cheaper.

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Electronic solutions are not cheaper but they are more precise.

For now, I am searching for an electronic solution which might help us to synchronize the position for 4 cylinders electronically. each cylinder has a built-in analog transducer and a proportional valve. Does anyone have a suggestion for me?

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Yes,
https://deltamotion.com/products/motion/rmc150/
To see it in action
https://deltamotion.com/peter/Videos/The house of dancing water - lift cues timelapes.mp4
To see more details
https://deltamotion.com/peter/Videos/HODW v6 20181227.mp4

Is the system already built?
How much mass must be lifted?
How much distance must be moved in what time?

The electronic synchronization of cylinders is easy. We, our customers, do it all the time. The critical part is getting the mechanical and hydraulic design right.
Few can design the hydraulics and mechanics correctly.

This was testing and practicing fo the making of the movie 2012 where whole movie sets were put on the 6 DOF platform.
https://deltamotion.com/peter/Videos/platform16ton.mov

I was just watching the 6DOF video. Were the kinematics being generated by a physical model?

Geoff White said:

I was just watching the 6DOF video. Were the kinematics being generated by a physical model?

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No! Watch the guy in blue. He his moving a waldo. This is a movie industry term. It is a small model of the 6DOF platform. The waldo just has 6 slide resistors that generate position references for the big cylinders to follow. This is common in the movie industry. However, for the real scenes the position generated by the waldo are saved in cubic splines so they can be replayed over and over again.

This video shows what our Indian distributor can do.
https://deltamotion.com/peter/Videos/Automate India 6DOF.mp4
All the motion is generated by the RMC150. Our Indian distributor started with a program I provided that converts x, y, z, yaw, pitch and roll to cylinder extensions. The Indian engineer wrote a user master program that generates the x, y ,z, yaw, pitch and roll for the slave program to follow.
I would go nuts listening to Devos 'Whip it' for any length of time.

Our Indian distributor retro fits Moog flight simulators. Normally the flight simulator down load x, y, z , yaw , pitch and roll for every video frame. I wrote and provided the code to convert x, y , z , yaw, pitch and roll to cylinder extensions. It isn't that complicated. I set the program up to do 100 frames per second but in most cases the frame rate is much lower.

We have many 6DOF applications. Some are flight simulators, some are race car simulators.

I believe that the company Norm Dziedzic works for owns the big 6DOF that is used to make the movies.

Geoff, even movies made in the UK use our controllers.

I was referring to the waldo (thanks RA Heinlein) as the physical model, an analog computer for cylinder positions. Was the feedback from the resistors used directly on the corresponding actuators or was it used to calculate the 6DOF result and then use that to control the cylinders?

I imagine if it was used directly, the ride on the platform could be messy if it exceeded the dynamics of the actuators.

Geoff White said:

I was referring to the waldo (thanks RA Heinlein) as the physical model, an analog computer for cylinder positions.

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The waldo is not a model as I think of it. A hydraulic model would be a gain, natural frequency and damping factor. I think of the waldo as being a master reference to gear to.

Was the feedback from the resistors used directly on the corresponding actuators or was it used to calculate the 6DOF result and then use that to control the cylinders?

Click to expand...

When using a waldo, the hydraulic cylinders and control are simply a reference follower. There is no model.

I imagine if it was used directly, the ride on the platform could be messy if it exceeded the dynamics of the actuators.

Click to expand...

Yes, I have more videos of the guy in blue practicing. The motion controller will set a bit or alarm if the hydraulic actuators cannot keep up with the waldo references.


The example from India is a much different case. The engineer wrote a program to generate x, y, z, yaw, pitch and roll, and this data was provided to the program I provided to them. I have no idea what the update rate is but the program I wrote would calculate the next set of extension to move to from the x, y, z, yaw, pitch and roll provided by the master program. My program would calculate a smooth 5th order polynomial to move to those positions.