ramp signal values, Gain values calculation for control simulation 1

[Naqeebi]

How to calculate the ramp signal values and then when i am using First order low pass filter in a Position Sensor. The system is used to control the directional valve connected with a piston Cylinder. I am also interested in calculating K values of Gain.
I dont know how to do them. I know its a control problem. Please direct me...
Thanks.
The issue is I need to control the gain values and the ramp signal so that I can close the piston in different time durations, such as 2 sec, 5 sec and so on. And analyse the different pressures that come up in the hoses. Well I am unsure of how to achieve this. I need to know where to look for the solutions. To do more work where should i look into. I have read some books like, Hydraulic control Systems ed.2 but unfortunately I cant find how to optimize or how to even calculate the Ramp. I know I have to use the Low pass filter with 20ms time delay. Please give an idea.
Thanks.

 

[2dye4]

Looks like you have a feedback control system. You need to develop equations for the system to determine the settling time of the closed loop system.

However driving with a ramp means that the valve will never close as it needs to constantly extend the cylinder in order to maintain balance.

What software is that simulation program.

 

[MacGyverS2000]

Please don't double- and triple-post...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Naqeebi]

Yes, 2dye4 it is a closed loop system. It is a software similar to AMESIM but more robust. I can give you the link in private if you ask for it. Its developed at our univerity. Can you guide me on how to develop the equations. I did find the control diagram but some transfer functions are still unclear to me. Can you please reply to this thread in more detail which book to use or some links perhaps which help me develop the ramp or step signals values.


P.S MacGyverS2000 (Electrical) Yes last time I didnt find the right forum

 

[2dye4]

Naqeebi i would start here at this link.

http://en.wikipedia.org/wiki/Closed-loop_transfer_function

You need to be able to work the algebra of the S plane to really devise a closed for expression for this.

G(s) will be the product of 4 terms

1 the first order lowpass filter
2 the gain K
3 the s domain description that relates the valve signal input to the pressure produced at the output of the valve.
4 another lowpass stage relating the pressure at the cylinder to the acceleration of the mass attached to the cylinder.

H(s) is relates the movement of the cylinder to the output of the position sensor.

Put all this together to make a probably second order system which the gain K can be selected to put the eigenvalues where they need to be for the speed of the response.

 

[Naqeebi]

2dye4
Its Hopsan Program. Download Location

http://www.iei.liu.se/flumes/system-simulation/hopsanng?l=en

I have made the equations but I need one thing to clarify
For the calculation of Kce (the servo valve’s flowpressure coefficient) how do i find del qL (flow) / del pL (load pressure)

Are these across the servo valve?
qL = (qL1 + qL2)/2
pL = p1 − p2

And then, the system I have shown you in figure is it,Valve controlled SYMMETRIC cylinder with mass load or Valve controlled asymmetric cylinder with mass load, because then the Xp (Valve displ.) and hydraulic resonance frequency and damping is different. I use a double acting piston.

 

[Naqeebi]

2dye4
Its Hopsan Program. Download Location

http://www.iei.liu.se/flumes/system-simulation/hopsanng?l=en

I have made the equations but I need one thing to clarify
For the calculation of Kce (the servo valve’s flowpressure coefficient) how do i find del qL (flow) / del pL (load pressure)

Are these across the servo valve?
qL = (qL1 + qL2)/2
pL = p1 − p2

Can the formulas be used for 4 port directional valve as well?
As they are for 3 port valve. How can i calculate for 4 port valve.

 

[2dye4]

Naqeebi

I can't help you with the fluid properties of the valve as i am clueless about this.

If it's a specific valve maybe there is manufacturer information.

Or post in mech engineering forum to see if someone there can help.

Thanks for the link..

 

[Naqeebi]

http://www.boschrexroth.com/country..._servo_valves/a_downloads/re29088_2009-01.pdf