marcinmrag

hydraulic cylinder speed function

8 posts in this topic

Hello,

How I can simple do function to measure the speed of hydraulic cylinder. I have a position encoder. I would like to have a actual speed not a average speed. Speed in mm/s.

Edited by marcinmrag

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But i read position by the analog input. I have a baluff encoder. So i have position value scaled from input. I create some function but im not sure if is working correct. I store position when i start movement than i calculate distance during the moment and i div this with the time. Time is very short is like 0,3-0,4 s. Cylinder speed should be 150mm/s for move up and 54mm/s for move down. working stroke of cylinder is really short like 40-45mm. When i move cylinder all the way up and down i get 200mm for up and 70 for down. It's possible that 40-45mm stroke is to short to rich the full speed? On this short distance i get 80mm/s for up and around 50 for down. Time reaction of cpu should be enough fast to make the calculation. I run this task i 2ms period time.

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But how I can check velocity? I have analog enckoder 0-10V. I can do some virtual axis for this or what? I have value from analog input which give me actual position. I would like to do function to show actual speed of cylinder.

Edited by marcinmrag

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Then you need to measure the rate of change of the said encoder reading. Put a constant timer which run every 100 ms for example. Or better, create a secondary Periodic Task that run for every 100 ms just to read this analog value periodically (from the Task Settings menu)

On each cycle, read the analog value of the said encoder. Subtract with its previous reading. Divide the remainder with 100 ms.
The result might get jumpy though. You can reduce the jumps by doing an moving-average of subsequent subtraction results (you can find that algorithm in the internet easily)

Now for the question whether the result displayed stands correct, that'll depends. Your encoder rated on 0 - 10 V, but for what distance?

Let's say 0 - 10 V equals 0 - 1000 mm, which means you'll have a precision of 1000 mm / 10 V = 100 mm/V
If your analog input card rate at 4000 for its resolution, the smallest voltage you can measure is 10 V /4000 = 2.5 mV
So that means the smallest unit of distance you can measure is (100 mm / V) x (2.5 mV) = 0.25 mm
Divide that by 100 ms sampling time, then the smallest change of speed that you can measure is (0.25 mm) / (100 ms) = 2.5 mm/s

That's the concept I can offer. Happy coding

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Synchronizing Hydraulic Axes in a Pultrusion Machine

 

https://www.techbriefs.com/component/content/article/tb/features/articles/9187 
Quote

An example of a master/slave synchronization command is the Synch Move Relative command, which is supported by Delta Computer Systems controllers. This command initiates a ratioed synchronized move of all the axes in a particular “sync group,” such that all the axes start and stop moving simultaneously, and at any point during the move, each slave axis has completed the same percentage distance (or ratio) of its move relative to a target value, which could be the position of a master axis. Figure 3 shows a plot of the motion of a slave axis (yellow – axis 1) following that of a master axis.

How can i synchronize Hydraulic Axes with Omron NJ501-1320 ?

What commands i need to use in Sysmac Studio ? Or how can i do this synchronizing of Hydraulic Axes with Omron NJ501-1320 ?

What  Linear Magnetostrictive Displacement Transducers (LMDTs) i'll need and what Proportional Servo Valve according to attached picture ?

 

A43F59CF-1605-4D75-A091-EBF290B39648-1602-000000CA76A049EC.JPG

E6608AE9-5182-44F5-B1F1-1A1F9692F6F9-1084-0000007C4F17A59A.JPG

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Quote

 To improve control of the pulling process, Entec recently upgraded its line of pultrusion machines to use an electronic motion controller. Previous Entec machines used a programmable logic controller (PLC) to output an analog voltage to servo valves driving the pulling cylinders. Pulling velocity was manually set by potentiometers according to the material being pulled, and the two pulling systems had to be individually set and manually adjusted by operators.

To replace the old velocity controls, Entec selected an RMC75P programmable motion controller from Delta Computer Systems Inc. (Vancouver, WA). Delta model RMC75P is a two-axis controller that outputs a variable control voltage to each of the two proportional servo valves of the pulling cylinders to precisely control the pulling velocity.

Entec’s machine uses Profibus to transfer information about speed, operating mode, and commands between a Siemens PLC that performs overall machine control and the motion controller (Delta RMC75P comes standard with a Profibus interface). The PLC tells the RMC what mode to go into, including selection among multiple pulling modes, and adjusts commands for machine operators, such as a command to “jog” the axes into a particular position.

 

 

Electro-hydraulic motion controller adds quality to pultrusion machine

https://www.controleng.com/articles/electro-hydraulic-motion-controller-adds-quality-to-pultrusion-machine/

I wish to do this Motion Controller , Hydraulic Axes Syncronization with Omron NJ501-1320

Edited by luk2011

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