Tuning 1 hydraulic axis with some/many moving as well.

So some of my hydarulic systems have multiple axes moving in sync. It is easy to tune 1 axis at a time but everything changes when all move. Why can't I tune 1 axis and have the others follow if I agree that I won't crash or they are not liable if I crash them. Synced systems have to move together to tune.

There reason why "everything changes when they all move" is that the system pressure drops. The system gain is proportional to the sqrt(Ps*Area-Fl)
where:
Ps is the supply pressure
Area is the area of the piston
Fl is the load force.
Send me a plot or take a screen shot and post it.

Normally when moving at a constant velocity the control signal is constant too. If the system isn't designed right the magnitude of the control signal must be always increasing as the supply pressure decreases.

There are a couple solutions.
1. Install a bigger accumulator.
2. Install a pressure transducer on the supply pressure and run the analog signal to the motion controller. Obviously the motion controller must have an analog input for this. The motion controller can then change the gains on-the-fly as the pressure changes. Actually there is an output scale that was added for this purpose. Few, less than 1 precent, do it though. Most get bigger accumulators.

So... Hum what do I do if I have to deal with what I have? I know with fudging I can make it better. To auto tune with all axes moving would do me better than fudging. Money is tight at this time. Even to add AI card since RMC rack is full. And accumulator is out for the time..
Peter the plot shows not enough flow. I have to find a way to equal what is there.

A trick I use

I have the system pressure turned down to about 200 to 300 psi below the system pressure and tune the axes up there one at a time because when all axes are running that is where the system pressure will be. Then I return the system pressure back to its normal pressure.

Guess I have to try that. Have you done this with a working sync system? Or is it therorie. Is that spelled correct?

It is spelled theory, get a spell check. I use one.

SMOKE said:

Guess I have to try that. Have you done this with a working sync system? Or is it therorie. Is that spelled correct?

Click to expand...

The actuator gain is proportional to the sqrt(Ps*Ape-Fl) where Ps is the supply pressure. Ape is the size of the push or powered side of the piston. FL is the load force. If supply pressure goes down the actuator gain goes down. THe problem is that with only one axis moving the supply pressure is close to the set point but when all the axes are moving the pump will not supply all the oil required until the pressure drops by 200-300 psi. Most pressure compensated pumps only have a proportional gain. How lame is that?

May be lame but I remember working with pumps with no swash plate, like vane pumps. If they will give me some time I will try try as you suggest.