Simulation of Water Tank Control System in LabView

[User002]

A water supply control system is shown in Fig.1. The tank of hight 100 cm is fitted with three liquid level sensors L1, L2 and L3 at 10 cm, 30 cm and 90 cm respectively. Each sensor output is “1” when the sensor is merged in the water, otherwise the output is “0”. A control valve is equipped to inlet water, while a pump is equipped to outlet the water. An alarm is used to report emergent state. As the tank is open air, the water in the tank evaporates.
Operational rules
• If the water level up to L3, the control valve will stop.
• If the water level falls below L1, the pump will stop, and the alarm should sound.
• Normally water level is between L2 and L3. When the level drops from L3 to L2, the valve does not open, and it opens when the level merges L2 or lower than L2.
• An operator should be able to press a button to request that the pump turns on or off, if the system is in a state where that action is allowed.

1. Design a front panel to indicate water level position and moving direction, sensors state, valve state, alarm state, and power state. Also display any necessary control button, etc.
2. Design block diagrams to implement control system functions to achieve the operational rules listed above. The block diagram should be divided into two parts: one part presenting the physical system; the other presenting the system control circuit. Due to that the physical system and the control section are in different places, the two parts must not be mixed.
3. Water evaporate rate, the valve flow rate and pump flow rate are not given and need the designer to set proper values. It is suggested the pump rate is higher than the pump rate, and the evaporate rate is much lower. The water level should be simulated moving up or down smoothly with proper speed.
4. Start the simulation by setting water level at 0 cm.

[Bob_Schor]

Great homework assignment.  What have you learned?  What do you know about things that take on values of 0 and 1 (hint -- what color should be the wire that ultimately comes out of processing this input)?  Do you understand the instructions?  [I'm particularly interested in the note "It is suggested the pump rate is higher than the pump rate" -- sounds like "lifting yourself up by your bootstraps"].

I recommend starting with pencil and (lots of) paper.  Draw (use pictures -- LabVIEW does, you know ...) it out, try to see where the data goes (I assume you know how to draw "how the data goes" in LabVIEW -- such pretty colors).

When you have a VI, or even better, a LabVIEW Project with a main VI and sub-VIs, try it out, and if it doesn't work or you get "stuck", post what you have, tell us where you are stuck, and we'll try to teach you how to fix it.

Bob Schor

[User002]

thats what i made of it but its not working

[GerdW]

Hi fais,

did you know we cannot edit/run/debug images with LabVIEW?

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@User002 wrote:

thats what i made of it but its not working

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In which way "it is not working"?

[Yamaeda]

If you have a level of 95, no LED is lit ...

[JimB.]

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@User002 wrote:

thats what i made of it but its not working

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As you are enrolled in this course you will presumably be an engineer someday. Imagine that an operator approaches you regarding some device that you have designed and the only information he provides you is that it is "not working." What does that even mean? What about it isn't working, and where do you begin troubleshooting?

Unless you are much luckier than me, you will find that this quickly becomes a pet peeve of every engineer. "Not working" is not a problem description.

Now, I can understand your very short posts that provide very little information since it appears that this is due today and you must be in a hurry. However, your first post comes pretty close to implying that you are asking for someone to provide a solution for you, so watch out for that plagiarism policy.

Now with the lecture over, I'm not going to bother trying to figure out what is "not working" because my first tip is going to be to reread the requirements and the description of the physical system. You are missing some requirements, implementing some controls that were not asked for, and all of your sensor logic is incorrect.

Hints:

• Take another look at the physical system being modeled. Is L2 no longer submerged when L3 is? Why is your alarm a separate comparison when it should be triggered by L1?
• Does this simulation start at 0?
• Have you made an attempt at satisfying task #2?
• Rates being left up to the designer and rates being left up to the operator are not the same thing.