TobyD Posted November 12, 2008 Report Share Posted November 12, 2008 QUOTE (blitzkrieg @ Nov 11 2008, 07:00 AM) Hey Minh, thanks for the code!and Toby D, I can't run the program ! Is that because of different version issues? I edited my previous post with a new version - download it again and give it a try. Toby Quote Link to comment
blitzkrieg Posted November 12, 2008 Report Share Posted November 12, 2008 Thanks Toby D! for the effort, the controller runs , but it always shows the PID output as the value of the upper limit. Quote Link to comment
TobyD Posted November 12, 2008 Report Share Posted November 12, 2008 QUOTE (blitzkrieg @ Nov 11 2008, 10:29 AM) Thanks Toby D! for the effort, the controller runs , but it always shows the PID output as the value of the upper limit. Like I said - I haven't tested the code. You'll have to check the logic/math. I just thought if it worked it could save you some time. If I have time I'll take a look at it later, but it would be a good exercise for you to go through the code and figure out exactly what it is doing. Quote Link to comment
blitzkrieg Posted November 14, 2008 Report Share Posted November 14, 2008 Thanks TobyD for the info! I understand all of it! My next step is to get the PID graph, so I bundled the Set Point v PV on to the wave form graph, but it just shows one straight line.. So I guess I should loop the while loop 'n' times to get the desired graph? any suggestions? Quote Link to comment
crelf Posted November 14, 2008 Report Share Posted November 14, 2008 QUOTE (blitzkrieg @ Nov 13 2008, 02:06 PM) My next step is to get the PID graph, so I bundled the Set Point v PV on to the wave form graph, but it just shows one straight line.. You will be looping anyway, as to acheive your setpoint. Maybe I'm not clear on what you're trying to do - as always, the best way to clarify is to upload your code so we can all see what you're trying to do. Quote Link to comment
blitzkrieg Posted November 14, 2008 Report Share Posted November 14, 2008 Here it is So basically, I input values to the SP and PV, I want the PV to reach the SP, and the graph to appear like this: Sorry for my lack of knowledge. Quote Link to comment
TobyD Posted November 14, 2008 Report Share Posted November 14, 2008 QUOTE (blitzkrieg @ Nov 13 2008, 12:13 PM) Here it isSorry for my lack of knowledge. You don't have to apologize for your lack of knowledge, that's why you're in school. But if we do the work for you, you will never gain the knowledge. I'm not sure what you are trying to do with the latest VI that you posted. You need to understand that the PID VI I posted is not even close to the full solution. That is just one piece of the system (or one subVI). You need to be calling the PID VI in a loop where each iteration passes in the updated Process Variable (and you'll need to connect the terminals because I forgot to do that ). The graph will then be updated in the same loop that calls the PID subVI. After looking at the Lab you posted, there are some pretty specific requirements. You need to layout the front panel, check the PID VI I posted to ensure it is using the same PID equation that the lab refers to, etc. You have a lot of work left to do. We all enjoy helping people out, but don't expect anyone to bail you out and do the work for you at the last minute. This looks like a lab that should require many hours of work on your part. Good Luck! (Read up on shift registers - you're going to need them) Toby Quote Link to comment
blitzkrieg Posted December 15, 2008 Report Share Posted December 15, 2008 TobyD ! Thanks for the advice! I have been working on it recently, and this is what I came up with.. I have simplified the formulae of the system, and got the PV. I need to know how to connect the PID output to the simplified formulae, so that the PID acts on the PV and brings it to the SP. Any help would be highly appreciated. Quote Link to comment
TobyD Posted January 14, 2009 Report Share Posted January 14, 2009 QUOTE (blitzkrieg @ Dec 14 2008, 10:49 AM) TobyD ! Thanks for the advice!I have been working on it recently, and this is what I came up with.. I have simplified the formulae of the system, and got the PV. I need to know how to connect the PID output to the simplified formulae, so that the PID acts on the PV and brings it to the SP. Any help would be highly appreciated. Sorry, somehow I missed this post. Do you still need help or did you figure out what was going on? -Toby Quote Link to comment
ned Posted January 15, 2009 Report Share Posted January 15, 2009 QUOTE (blitzkrieg @ Dec 14 2008, 01:49 PM) TobyD ! Thanks for the advice!I have been working on it recently, and this is what I came up with.. I have simplified the formulae of the system, and got the PV. I need to know how to connect the PID output to the simplified formulae, so that the PID acts on the PV and brings it to the SP. Any help would be highly appreciated. This isn't directly related, but is anyone else seeing a bug with this VI? I opened it in 8.6, did "Remove Sequence," and all the wires to tunnels in the sequence turned invisible. LabVIEW thinks they're still there, the run arrow isn't broken and if I put the cursor over where a wire should be the cursor changes and the right-click menu pops up appropriately, but there's no visible wire. Quote Link to comment
TobyD Posted January 15, 2009 Report Share Posted January 15, 2009 QUOTE (ned @ Jan 14 2009, 04:38 AM) This isn't directly related, but is anyone else seeing a bug with this VI? I opened it in 8.6, did "Remove Sequence," and all the wires to tunnels in the sequence turned invisible. LabVIEW thinks they're still there, the run arrow isn't broken and if I put the cursor over where a wire should be the cursor changes and the right-click menu pops up appropriately, but there's no visible wire. I noticed the same thing a while ago and then promptly forgot look into it more. The other issue is if you run "diagram cleanup" it ends up hiding a bunch of wires and doing weird things. Quote Link to comment
David M. Posted May 29, 2009 Report Share Posted May 29, 2009 Hi all, sorry to interrupt... I read this forum and I have a problem that I think all of you can give me the answer... I have search PID example, but I can't open them because i haven't installed the toolkit... Then I search the PID toolkit, but none of them is PID toolkit but Fuzzy logic control... can you give me a link to get the right toolkit..? Sorry if my language not really good or a little rude, I'm an Indonesian... Thanks before... Quote Link to comment
crelf Posted May 29, 2009 Report Share Posted May 29, 2009 QUOTE (David M. @ May 28 2009, 01:54 AM) can you give me a link to get the right toolkit..? You can get the http://sine.ni.com/nips/cds/view/p/lang/en/nid/1394' target="_blank">NI LabVIEW PID Control Toolkit here. Quote Link to comment
David M. Posted July 7, 2009 Report Share Posted July 7, 2009 (edited) Hai all, I got a PID example from here, and I try to apply at the water tank simulation from Lab VIEW... But the curve just go up and didn't go stable. I must press the restart button if I want to use PI control... I'll attach my VI... Please tell me where's my fault... thanks before... uji coba.vi Edited July 7, 2009 by David M. Quote Link to comment
David M. Posted July 8, 2009 Report Share Posted July 8, 2009 And if it doesn't go up, it would never touch the set point... Until now I still don't undferstand why the curve just like that... Quote Link to comment
George Pollock Posted July 9, 2009 Report Share Posted July 9, 2009 As a general comment, I am doing closed loop temperature control on a LV 8.6 system using "bang-bang" control. PID is almost a "knee jerk" when it comes to control algorithms, but it is a costly item from NI and, at least in my situation, not needed. Not the cost, not the aspirin of working with PID. "Bang-bang", if it doesn't ring a bell, is the way everything in your domestic world is controlled. Your heater, your air conditioner, your toaster, your oven, your electric blanket (probably). The only proportional control I can find in my domestic world is the engine thermostat on the family car. "Bang-bang" needs no analog output, no heavy math. The only requirements are that the process driving force (in my example, the heaters) is not over-sized for the problem and that there is enough time in the process. Quote Link to comment
David M. Posted July 9, 2009 Report Share Posted July 9, 2009 As a general comment, I am doing closed loop temperature control on a LV 8.6 system using "bang-bang" control. PID is almost a "knee jerk" when it comes to control algorithms, but it is a costly item from NI and, at least in my situation, not needed. Not the cost, not the aspirin of working with PID. "Bang-bang", if it doesn't ring a bell, is the way everything in your domestic world is controlled. Your heater, your air conditioner, your toaster, your oven, your electric blanket (probably). The only proportional control I can find in my domestic world is the engine thermostat on the family car. "Bang-bang" needs no analog output, no heavy math. The only requirements are that the process driving force (in my example, the heaters) is not over-sized for the problem and that there is enough time in the process. Sorry I don't get it... I have already set the PID for the increasing of the water tank ( as a pump), but the options is just two, if it don't go up and up, then it will never touch the set point and get stable there... I think there's something wrong in the PID or may be at the "Q in"... but I can't be sure with both of them... so confusing... I have always try to modify the variable of the PID but the result is always the same... and I tried to modify the "Q in", then it got worse and worse... Quote Link to comment
David M. Posted July 19, 2009 Report Share Posted July 19, 2009 this is the VI and sub VI... Jadi.vi limitter.vi PID.vi Qin.vi Qout.vi Quote Link to comment
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