Specifying the numerator and denominator of the transfer function equation

hi
I am going to simulate the second odder problem. But I have problem when I try to define the 2nd odder transfer function
by using externally. I have attached the VI in this mail .
any information in this regard highly appreciated
thanking you
danushka
Solved!
Go to Solution.
Attachments:
second_order_systerm_8.2.vi ‏80 KB

Hello Danushka,
You would need to create a control from the transfer function. Then on the front panel, just expand the denominator column to get zero and first order for the denominator as shown here. Let me know if this helps.
Andy Chang
National Instruments
LabVIEW Control Design and Simulation

Similar Messages

The transfer function of the PID block doesn't show the derivator.

Hello,
I am trying to use the PID vi, but I when I try the box by itself, it doesn't behave as a "clasic" PID should behave. The main problem is that I don't manage to see the derivator. In the attached vi I compare the transfer function of the PID vi with the transfer function of a PID built by me. My version shows all what a PID should have: integral section (with decreasing magnitude and -90 phase), center area (with constant magnitude and 0 phase), and derivative area (with increasing magnitude and +90 phase).
The PID vi only shows the integral part.
You can also select a step input, and see the output directly. If you choose a large enough derivative time (100 times bigger than the integrator time), and you look closely to the first part of the output, you will see the pick due to the derivator in my version, but not in the PID.vi version.
Does anyone knows what am I doing wrong?
Kind regards,
Pablo Estevez
Solved!
Go to Solution.
Attachments:
TestPID.vi ‏31 KB

Dear Nathand,
Thanks for your answer, I tried the change and you are right. That shows that this not a standard PID, since that means (and actually I can see it now by checking inside the vi) that it is not using the derivative of the error but the derivative of the process variable. I know that this is used sometimes to prevent the effect of fast changing set-points, but it is a shame that they do not comment on it in the help, and that this is not a selectable feature. Do you know if there is a way to edit these pre-packaged vi's?
One more question, about the labview style. I included the sequences just to group terms and make the code more readable to separate the integrator from the derivator and not have a knot of entangled signals. Specially when I run the clean-up diagram, it gets very entangled. I have been looking for another way to do that (container boxes, groups). It would be nice if you could suggest me something I can do for it.
Thanks again,
Pablo

Where to set the Transfer Function in Photoshop CS5?

Where do I set the Transfer Function in Adobe Photoshop CS5?
My college newspaper uses Transfer Function to control dot gain in B&W photos, saving them as EPS files.
In CS4 it was a button in the print dialog box, in the output section. It brought up a curves-like dialog to set a transfer curve. That button is gone now, and the help files offer no help.
The help files say "Save your file in the Photoshop EPS format, and select the Include Halftone Screen and Include Transfer Function options in the EPS Options dialog box." but doesn't say where to create the curve.
Here's CS5. Compare to CS4 below, and the larger shot below that.
Here's CS4
Here's the transfer curve dialog box in CS4 that I can't find in CS5

Hello!
It might have been removed for the same reasons screen was removed: http://forums.adobe.com/message/3438135#3438135
I'd try to use the same workaround: set a document transfer curves as you want, save it as a template, then open it in CS5.

How to implement the Transfer Function in Real Time VIs?

Hi all,
I'm relatively new to Labview Real Time modoule and want to implement one Controller(not PID one) in Deterministic Loop! I have already designed discrete Transfer Function and searching for the way to build one Controller with it! Is it right to use the Simulation Loop instead of Timed Loop (in this case Deterministic loop) and implement the controller in it?! If it's correct so, should I use the same clock and Priod as Timed Loop?!
It would be very helpful, if there is an Example about using transfer function in Real Time Loops!
thanks for your help,
Mohsen

Hello mhmdi,
Sorry I can't open your VI (looks like it is a new version of LV than I have installed).
You're right - you don't need to convert to a difference equation if you have the CD&SIM Module which can take discrete time transfer functions directly. You don't need shift registers with this function, as it is effectively done internally. If you don't have CD&SIM discrete TF's can be implemented easily just in a timed (or while) loop with feedback nodes or shift registers to replicate each z-1 you need.
Some more ideas:
There are many configuration parameters and options with the Discrete TF VI - which you need to understand for your application and make sure are correct. Sometimes implementing in a basic form (timed loop and shift registers) allows you to see what is happening without any confusing options you might not need.
Are you using the Discrete TF VI in a Simulation Loop ? You might need to think if the loop being used is appropriate for a Real Time application. Maybe the timing of the TF, the loop and the DAQmx data are not all suitable for each other.
I'm not familar with DAQmx, so not sure about any specific real-time aspetcs of that.
"if the sample frequency of the discrete transfer function in the timed-loop is at multiple integers of the sampling rate (e.g. 12000 Hz for tranfer function and 4000 Hz for sampling rate, 12000=3*4000), would it somehow improve the resolution of the controller command?"
This could actually make things worse - but depends on your transfer function if it is a problem. Think about it this way - in the scenario you state the input signal going into the Discrete TF will only change once in every three samples, that means if your transfer function includes a 1-z^(-1) factor (i.e. a derivative) - that will be zero for two samples then jump up for the next sample. You'll observe a very jittery/noisy signal, but the noise is due to samples not being correct. This will also occur if the sample times are very similar but go in and out of sync where you may get the occassional sample that is the same and hence the occassional zero in the TF.
In an application I had we had problems trying to get the data coming into a timed loop and the timed loop itself synchronise, and before it was fixed the control signal was very jittery.
Consultant Control Engineer
www-isc-ltd.com

System Identification and Transfer Function of the LEGO MINDSTORM NXT Robot

Can anybody please help with the below question.
Using your LabView interface, input different values of power and record the output value of the number of wheel rotations. You can convert the latter into speed by measuring the diameter of the wheel. Then, type ‘ident’ in the command line of Matlab to launch a graphical user interface for system identification. Using the data collected for input power and recorded speed, you can derive the transfer function for your robot in the Laplace domain.
You will notice that it is possible to approximate the transfer function to a first order system.
Add disturbance to your system such as wind drag, road profile or friction. You might want to model the disturbance as a sinusoidal waveform.
Analyse the system response in LabView in order to tune the response.
Finally, write a LabView program to test your controller.
Set both Integral and Derivative to 0
Increase the value for Proportional controller to 0.5, 0.8, 1, 1.1, 1.3, and 1.5
Select a suitable simulation stop time.
Compare each simulation results and draw some conclusions.
Record the steady-state error. Has it dropped to near zero?
Record the rise time. Has it decreased to less than 0.5 second? And for what values of Kp?
Check whether this response is realistic i.e. a real cruise control system generally cannot change the speed of the vehicle from 0 to 10m/s in less than 0.5 second.
Adjust the gain (Kp) to give a reasonable rise time and add an integral controller to eliminate the steady-state error.
Change both Kp and Ki and see what happens to the response. When you adjust the integral gain Ki, start with a small value since a large Ki can destabilise the response. (Ki =0.001, 0.002, 0.003, 0.004).
Then you need to adjust both the proportional gain Kp and the integral gain Ki to obtain the desired response. Record the values of Kp and Ki that can meet all the design criteria.
Write the PID-feedback control LabVIEW program as described above.
Does it work? Quantify! Show us it is working
Hand in a short report on the PID project on the cruise control of the LEGO MINDSTORM NXT Robot. Your report should contain an introduction to cruise control and uses of PID controllers, a brief explanation of how PID feedback control works. The printout of the Block Diagram and Front Panel of your LabVIEW program should be attached at the end of your report.
Put it all together. There are many questions that can be explored and written up in the result section. Be creative.
Here are some things that may be addressed: Check whether your system can stabilise speed to within 1%. What are the optimal PID parameters that you have found? Can you choose PID parameters to both reach the set speed quickly and also maintain the speed within good accuracy once the system has reached the set speed? Can you control the speed of small steps? Explain your results?

Thanks for that.
DanHarryman wrote:
HI ToolMonkey
You should be able to build control system to do this using PID control VIs. The following paper is a good place to start when working with PID systems.
http://www.ni.com/white-paper/6440/en
Let me know how you get on using some of the functions in this.
Thanks
Dan.H
UKAE

Numeric Operations with transfer functions

Dear Friends,
I am relatively new to labview and i am using labview 8.2. I wanted to know that how can i perform a numeric operation between an array and a transfer function. I am attaching a sample of what I have been able to do, but the output is in the waveform pattern. Can anyone suggest a better way to perform this operations. Any suggestions will be of great help.
Thank you.
Shashank

Shank,
What is the operation that you are trying to do with Control Design? It is not very clear what the fnal goal. There are several ways to do things with LabVIEW that would be more suited for your final problem.
Just to let you know, as of LabVIEW 8.5, we introduced basic operations of models (that can be in State-Space, Transfer Function and ZPK). So, you can multiply a scalar value by a Transfer Functions model, giving a transfer function scaled back. Before, you would need to do operations with that.
Additional to this, also consider using Simulation Module 8.2 for changing the paramters on the fly. I noticed that you are trying to use the Simulation Signal Express VI and try to simulate the transfer function on the fly. This is EXACTLY what you can do with Simulation Module, but in a more natural way. If you have LabVIEW 8.5, the Control Design Toolkit and the Simulation Module are part of the same product called Control Design and Simulation Module 8.5.
Hope this helps. Let me know if I can of more assistance!
Barp - Control and Simulation Group - LabVIEW R&D - National Instruments

How do I specify the gmail outgoing server if I have multiple gmail accounts in my mail? I have 2 business accounts and when I send mail from one account, it is sent from the other account and the sending email is not from the correct account.

I love my apple email and do not want to use google mail on safari. However, I have 2 gmail accounts set up on apple mail, but when I send mail from one of my gmail accounts (I choose the specific gmail account in the drop down window), it actually goes out as if it is from the other gmail account. I can't have that happen because one is my job, the other is a personal business account and unfortunately, the mail from both gmail accounts want to send through the personal business account. How do I make it send from a specific gmail account? I even tried deleting the accounts and setting them up again hoping I set it up wrong in the first place, but to no avail, it is still doing the same thing except this time I set the job account up first and then the personal business account and now everything goes from the job account! The only good thing is that the incoming messages work properly and they go into the correct inbox. Somebody please fix my outbox!

In Mail Preferences/Accounts/each GMail account, set up the SMTP Outgoing Server for each account separately, going into SMTP name/edit/Advanced and specify the Username of each account. The Outgoing servers must be two different servers, authenticated by the Username and Password of each.
Otherwise, the GMail SMTP server will change the from address to that of the account where the SMTP server was setup.
Ernie

Is there a way to improve the sign in experience so that users don't have to specify both address and username?

I've wondered this for a long time-is there a way to set up Lync so that I can have users sign in with just the sign in address, and not have to specify the username as well? Things tend to go like this:
User launches lync client-types sign in address and password (in this case [email protected])
Sign in will fail, and now they'll need to specify the username (in this case CTT1\user) and retype their password
Now sign in succeeds (and it'll remember credentials)
Is there a way to fix things in DNS so that step 2 isn't required? It's a pain for the out of the box experience for new users, and the fact that the login has to fail to be able to specify the username in the first place is a little counterintuitive.
Is there a record we can create so that the domain name (in this case CTT1) is inferred from the SIP domain?

Well if you want a "single signon" experience, the Workstation will need to de join to the domain :-) otherwise it will prompt for the Username and password for authentificaiton.
You can then check the save password box.
For remote user that are NOT on the domain, same behavior, you will be prompted to enter Username/Password.
If a post is helpful, please take a second to hit the green arrow on the left, or mark as answer, thanks.
Jean-Philippe Breton | Senior Microsoft Consultant | MCTS, MCITP, MCT, Lync MVP

Getting error while creating form and report on webservice: ORA-20001: Unable to create form on table. ORA-02263: need to specify the datatype for this column.

i am using the following description to create a web service reference:
web reference :REST
Name :Yahoo Map
URL :http://local.yahooapis.com/MapsService/V1/mapImage
HTTP Method: GET
Basic Authentication: No
Add Parameter:
Name       Type
appid        String
location    String
Output Format: XML
XPath to Output Parameters : /Result
Output Parameter:
Name       Path       Type
Url          /text()      String
Then i tried to create form and report on webservice:
Web Service Reference Type: Yahoo Map
Operation: doREST
All the fields i keep as default
I tick the checkbox (url)in report Parameter
After clicking next whereever required i click create button
I get the following error
ORA-20001: Unable to create form on table. ORA-02263: need to specify the datatype for this column.
Please someone help to solve this as i need to fix it urgently.

i exported the application from apex.oracle.com and imported it to our environment
import went fine, but when I ran the IR page I got
ORA-20001: get_dbms_sql_cursor error ORA-00904: : invalid identifier
evidently the problem is a lack of public execute on DBMS_LOB, which is used in the generated IR source.
while waiting for the DBA to grant privs on DBMS_LOB, changing the dbms_lob.getlength call to length() fixes the IR.
however, i am not getting the download link on the associated form page... changed templates, that's not the issue -- we'll see if that's a dbms_lob issue as well

APEX:Getting error while creating form and report on webservice: ORA-20001: Unable to create form on table. ORA-02263: need to specify the datatype for this column.

I am using Apex 4.2.2.00.11
am using the following description to create a web service reference:
web reference :REST
Name :Yahoo Map
URL :http://local.yahooapis.com/MapsService/V1/mapImage
HTTP Method: GET
Basic Authentication: No
Add Parameter:
Name       Type
appid        String
location    String
Output Format: XML
XPath to Output Parameters : /Result
Output Parameter:
Name       Path       Type
Url          /text()      String
Then i tried to create form and report on webservice:
Web Service Reference Type: Yahoo Map
Operation: doREST
All the fields i keep as default
I tick the checkbox (url)in report Parameter
After clicking next whereever required i click create button
I get the following error
ORA-20001: Unable to create form on table. ORA-02263: need to specify the datatype for this column.
Please someone help to solve this as i need to fix it urgently.

336554,
Looks like there is a 127-column limit on the number of report columns supported when using that wizard. Do you have more than that?
57434

How to install XE and specify the SID (instead of XE) during install

I would like to use Oracle 10g Express Edition for development purposes but I already have an existing project that requires a specific SID.
I tried following some instructions on asktom.oracle.com on changing the SID but it was disastrous and did not work.
Ultimately I have to rip XE off and reinstall everything because it was so mucked up.
I would like to reinstall XE but during install specify the SID just like I can with Oracle 10g R2 Enterprise Edition.
Can someone please tell me how to do this, and Oracle if you are listening, can you modify XE so that the SID can be specified on install? This one thing is a deal breaker for me and am considering falling back and using postgresql for the initial release of this product instead of Oracle to clients. I am sure many of them would upgrade to Oracle Enterprise edition if I were able to release a product based on XE first.
thanks
OracleTek

At the time of installation , you can't change SID XE.
After installation, you can add another service name
Check following thread for more details
Re: How to create service on Oracle 10g XE
- Virag Sharma
http://virag.sharma.googlepages.com
http://viragsharma.blogspot.com

Used to convert all my videos into iPhone mp4 format using Any Video Converter - then add it to my iPhone 3GS. But last few days, I cant add video files to iTunes. and the iTunes doesnt even specify the reason except for that "files are not supported"

Everyting was perfect earlier. Used to convert all my videos into iPhone mp4 format using Any Video Converter - then add it to my iPhone 3GS. But last few days, I cant add video files to iTunes. and the iTunes doesnt even specify the reason except for that "files are not supported"
Everything is fine.
-They are the right format
-Quicktime is updated
-I have tried simply dragging them into the 'movie' library
-I have tried going to file<add file to library
Nothing works, has anyone else had this problem and found a way around it?
Any and all help appreciated.

In addition to Mike's suggestions, you only have 4GB of RAM and Mavericks does use more RAM than other versions. You may also want to look at the apps that startup on login and the possiblity of upgrading RAM.

How to Specify the environment variable JCE_POLICY_ZIP and restart

Hello All,
I am installing the ABAP SAP NetWeaver 7.01 SR1 ABAP Trial Version.
sapinst.exe installed successfully.
I am installing the sapinstgui.exe but I got the following message:
Program is starting... Please wait!
Path: C:\Users\George\AppData\Local\Temp\sapinst_exe.6220.1246290325
jre\bin\java.exe
For the requested processing mode java policy
files within the used SAP JVM are needed.
Specify the environment variable JCE_POLICY_ZIP and restart.
See also SAP note 1238121.
Exit status of child: 10
JRE is installed in C:\Program Files\Java\j2re1.4.2_19
How do I specify the environment variable JCE_POLICY_ZIP?
Thanks
George
Edited by: George King on Jun 29, 2009 9:01 PM

Hi everyone,
I had the same problem and found the solution !
I was trying to setup the GUI thanks to sapinstgui.exe from the trial download folder and I got the exact same message,
The problem is not the policies but the installation file.
The installation file for the GUI is located at :
<extract_folder_SAP_trial_version>\GUI\SAP_GUI_FOR_WINDOWS(...)\SAP_GUI_for_windows_(...)_Components.exe
Hope it helps !
Nicolas

"The interface name given does not specify a valid and existing interface."

Hi nice guys,
I'm trying to use the XNET APIs to set Master task to Slave with LIN protocol. As I have no Experience before, there's something problem like the Interface of the NI USB-8476S can't be detected. The prompted windows presents following infomation:
Error -1074384758 occurred at XNET Create Session (Signal Output Single-point).vi:1
Possible reason(s):
NI-XNET: (Hex 0xBFF6308A) The interface name given does not specify a valid and existing interface. Solution: Use a valid and existing interface. These can be obtained using MAX, XNET system properties, or the LabVIEW XNET Interface IO name. If you are using CompactRIO, refer to the topic "Getting Started with CompactRIO" in the NI-XNET Hardware and Software Help.
but in the NI MAX, the device is detected as "LIN0". Even the interface input control in the NI examples shows the error. But if I take the CAN Frame API, it works well.
Does anyone have some idea. I'm so preciate. Tanks in advance.
best regards
Melo

Melonetern,
When do you receive these errors? Does this happen when you try to run your code or our examples? On top of that, does this error happen immediately or does it take a while? Is this happening in LabVIEW or another interface?
If you could give us the versions of software you are using as well as the XNET driver versions that would be very helpful.
Matt J
Professional Googler and Kudo Addict
National Instruments

Specify the output file path and print name when printing pages

hi,
how can i Specify the output pdf file path and print name when i am using the function PrintPagesSilent from AcroAVDoc Object.
My Code :-
Acrobat.AcroAVDoc doc = new Acrobat.AcroAVDoc();doc.Open(path,
"temp");

Dear Irosenth,
i try with different format (doc, docx, xls, jpg, bmp and txt) and it working successfully, but it give an random name for the file which saved in default folder for Adobe PDF print.
you can use the following function:
private void PrintPDF(string[] inputfilepath){
foreach (string path in inputfilepath){
Acrobat.
AcroAVDoc doc = new Acrobat.AcroAVDoc();doc.Open(path,
"temp");
Boolean v = doc.PrintPagesSilent(0, ((Acrobat.AcroPDDoc)(doc.GetPDDoc())).GetNumPages() - 1, 0, 0, 1);doc.Close(1);
and calling it by the following code:
PrintPDF(System.IO.Directory.GetFiles("c:\\t\\printjob"));
copy all files that you want to convert in side the mentioned path and run it program, then check the defualt print path for Adobe PDF printer.
test it and reply me. thanks again

Specifying the numerator and denominato​r of the transfer function equation

Similar Messages

Maybe you are looking for

Specifying the numerator and denominator of the transfer function equation