Creating a simple closed loop control

Hi everyone,
I need a bit of help creating a (very) simple closed loop control.
Note: I am using 3 Measurement Computing boards: one USB-2416, and two USB-TC's. Since Measurement Computing has their own driver (called ULx), it might be a bit more difficult to understand than the NI drivers, but keep in mind ULx is the equivalent to DAQmx.
I need to be able output a 0 or 1 binary value based on measurements from 4 voltage input channels compared to constants. Ie. if voltage measurement < 3.5 (constant), send a boolean value (see a, b, c, d in attached photo) which in turn gets sent to the ULx Write VI, and that outputs the binary value of 0 or 1. The problem I've run into is that I need to "compare" single chanels from different boards, which gives me single boolean values for each channel. The ULx Write VI only accepts boolean arrays. Is there a way (and there probably is, I just haven't been able to find it) of arranging these lone boolean values into a boolean array?
(see attached file for what I have so far)
PS. I am a COMPLETE rookie, only been using LV for a week or so, so please explain everything as if I have no clue what's going on.
Thanks in advance!
Solved!
Go to Solution.

Hi,
the attached example I've made should demonstrate what you need to do.
Some things to think about:
1. It seems that the ULx vis return arrays of signals. If so you can select signals with "index array" as done in my example. That consumes less space and does not change the type of the signals to variant.
2. If you compare the signals to your constants you will receive boolean arrays because every element of the measured signal is compared to the constant (see my example). You may then decide how to process that info - another hooray for signals :-)
Regards
Florian
Attachments:
Example01.vi ‏24 KB

Similar Messages

Stepper motor closed loop control using 7344

I have some question about the closed loop control of stepper motor using 7344. From the NI website I got that closed loop steppers work differently from closed loop servos. Instead of adjusting the output on each PID iteration like a servo system, closed loop steppers will do a pull-in move at the end of a move to adjust for any difference between the target position and the encoder feedback. By default, it will attempt the pull-in move three times.
Now for example I got five points: (0,0) (10,20) (30 40) ( 31 60) (50 65). The request time interval I set as 10ms. This mean that in the first 10ms, the machine should move from (0 0) to (10 20). But for some reasons the machine can not move to (10, 20), it moves to (8,16) and the first 10ms passed. In the second 10ms, how it move? Move from (8 16) to (30 40), If like this, the following error will accumulated. In practise, it is not accumulated. Is there anyone can explain something about the closed loop control of stepp motor? Thanks a lot!

Requested Interval is additional data for the Position buffer type. The Position buffer type requires a Requested Interval parameter, and indicates the time between contouring data points in milliseconds. For all other buffer types, the Requested Interval parameter is ignored.
The controller will use the closest value it can that is greater than or equal to the interval value you requested. Your time interval must be an even multiple of the PID rate.
For example, given a PID rate of 250 ms, a time interval of 11.2 ms between points is physically impossible, so a call to configure buffer with an interval of 11.2 causes the buffer to actually be configured for 11.25 ms, since 11.25 is the nearest possible interval greater than 11.2. The following table shows valid intervals for each PID rate.
My question is like this. For example I got five points: (0,0) (10,20) (30 40) ( 31 60) (50 65). The request time interval I set as 10ms. This mean that in the first 10ms, the machine should move from (0 0) to (10 20). If it is impossible for the machine to move from (0 0) to (10 20), there are two ways to solve this problem. First is the time interval is 10ms and assume it move to (8 16) within 10ms and take (8 16) as the start point and (30 40) as the end point of the second move. Second is extend the time interval, assume it takes 14ms to move from (0 0) to (10 20). After 14ms, the (10 20) is the new start point for the second move. I think it works as the second ways.If not, the following error will accumulated. Is there anyone can explain something about the closed loop control of stepp motor in detail? Thanks a lot!

Closed loop control of step motors possible with 7344?

Hi All
I have been looking around here for a while for an answer to this question.
For me, a closed loop control system is correcting for following errors all the time, also when the move is complete.
If the load on a system changes, there will often be a need for compensation in order to keep the position right. Then you need a closed loop control system.
I have made a system using DC motors with a 7342 controller. We are in the process og getting a new similar system, where the manufacturer chosed stepmotors in the believe that it can be used in closed loop.
Is it really true that the NI version of closed loop is only performing a what you call a "pull-in" at the end of the move in order to correct for lost steps or flexibility of the connection between motor and object/encoder?
I would call this "backlash compensation" or something like that.
Why dont you make a real closed loop option. The control voltage from your servo motor control, could be fed into a voltage-frequency converter with a matchin sign signal.
This shouldn't be too complicated to accomplish.
/b

You are right. NI motion control boards don't apply a control algorithm
during moves when configured in closed loop stepper mode. In this mode
the board monitors the following error during the move and generates an
error when the following error limit is exceeded and they start the
pull-in moves at the end of the move if necessary.
If you really want to do PID control with stepper motors you still
could connect an external V/f converter to the DAC outputs of the board
and control the axes like DC motor axes. Some vendors implement this
feature on their board but NI has decided not to do that as we don't
think that this approach provides a good solution. Here are some reasons:
The most important issue is the fact that you could easily exceed
the maximum rate of change of the motor frequency in the case that the
following error increases during the move. For a DC motor this would mean that the
voltage of the controller increases to compensate for this error and
the motor will follow - probably with some delay, but it will follow. For
the stepper this could mean that the acceleration becomes so high
that the motor stops immediately as it can't follow with a delay like a DC motor. What
should the controller do then? Restart the move automatically? Generate
an error? There is a big chance that you end up with a system moving in a stop and go mode.
The second issue is related to the control algorithm itself. The transfer function of a stepper motor is not really linear so it will be quite hard to find good tuning parameters. A DC motor can be tuned by analyzing the step response and the Bode plot. For the reasons that I have described in 1.) this won't work for a stepper so how should you tune it?
I have talked to some motion control engineers who have tried to control steppers with a PID algorithm and they all agree that this is a real pain and it's not recommended.
So if your system requirements involve online following error compensation I strongly recommend using a DC motor.
Best regards,
Jochen Klier
National Instruments Germany

Closed loop control of DC motor drive using PCI 6251

Hi
i am using NI PCI 6251 for closed loop control of dc drive.(shunt motor,220v, 0.5HP, 2.5A rated, 1500RPM)
the dc motor is fed from a bidirectional dc-dc converter. this converter works in boost mode(forword motoring) and buck mode(braking mode/battery charging)
the converter is built using mitsubishi IGBT module. at low voltage side of the converter a battery bank of 48V is connected and high voltage side the motor is connected.
An IR sensor is developed to measure the speed of the motor and a hall current sensor is used to sense the converter current.
in the control part i have an inner current control loop(PWM controller) and a outer speed control loop.both controllers are PI controller. To measure the speed i have used counter of the DAQ assistant, then frequency. then this frequency is converted to RPM using labview.after giving the speed and current signals to the controllers , then i started tunning the PI gain, but at the starting the duty cycles was 100%, so the IGBT got damaged immediately. now how to tune the controllers during the closed loop operation. the switching frequency of the converter is 20KHz.
can any body suggest me how to run the dc drive in closed loop ?
thanking you.

Hi Premenanda
The freq data receiverd from the daq assistant has the units of Hz, or in terms of motor speed, rps (rotations per second). I can see that you are trying to convert that to rpm (rotation per minute). which can be done by dividing the rps speed by 60. Instead, you are multiplying it by 60 and also comparing with 2000. the resultant multiplied value is displayed in your program only if it is smaller than 2000.which is causing the problem here.( as seen in file 'original code.png)
I have attached a file named 'modified code.png' that shows how the conversion from rps to rpm is done. Please do the required changes in your code and let me know if it works.
Attachments:
modified code.png ‏18 KB
Original code.png ‏15 KB

DC motor closed loop control through labview using usb 6008

Hello
i am doing a project in which i want to control the speed of a DC motor (PID control) through labVIEW 2010. I am having a DC motor, a drive unit that regulates the voltage to the motor by getting analog voltage from 0 to 3.3V ( it can be used for both directions) and i also have a NI usb 6008 board. The problem is that i can't feed the usb 6008 with the digital signal from my hall effect speed sensor. Is it posible with this setup to control the motor?? I can also try to use the pulse as analog input and trasform the frequency into rpm's. Then i am thinking of generating an analog signal to feed the motor drive. If you have any further suggestion of a probably better hardware setup would be more than helpfull to me.
Sincerely
Jason Chaloulos

Hello Michael
Thanks for the reply. I came across those topics before and all of them are trying to generate a PWM signal as output i want to use just an analog signal output so timing on the output is not that important i guess. i am struggling on getting the frequency from the digital input signal that my hall effect sensor generates. Since the maximum speed of the motor is 3000 rpm and with my tooth wheel the maximum output frequency of the sensor will be 300Hz which i see its way less than the limitation of my ni board. Is there any tutorial documentation that might help me with this one ? Thank you in advance.
Kind regards
Jason

Closed loop velocity control based on load cell force

Hello,
My application is for a drill, that drills into rocks of various densities for the purpose of collecting rock core samples.
My setup has 2 motors which get controlled, one spins the drill bit at a constant velocity, the other moves the drill mechanism along a Z axis.
For efficient cutting, it is desired to apply a constant force between the drill bit and the rock. I have a load cell which measures the force being exerted by the drill bit on the rock surface, and this force can be adjusted by changing the velocity of the Z axis. So I would like to employ closed loop control to adjust the Z axis velocity to maintain a constant force on the rock.
Platform: cRIO 9073, with NI 9505 & 9215 Modules, Labview 2010 Full with RT and FPGA modules.
The load cell is by Transducer Techniques, and I use their TMO-1 module to condition the signal, the output of which is attached to an input of the 9215 module, where 0-100 lbs equates to 0-8VDC.
The motors and encoders for the Drill and Z axis are connected directly to the 9505 modules.
Right now I am using a modified version the example found in ...\examples\CompactRIO\Module Specific\NI 9505\Velocity Control (closed loop)\Velocity Control (closed loop) - NI 9505.lvproj to accomplish velocity control of the motors.
My questions are:
1) Do I have the appropriate NI hardware/software for this task?
2) With my current hardware setup, what would be an appropriate way to control my Z axis velocity rate based on Analog feedback from the load cell?
3) Development time is a critical factor, so are there any toolkits etc that are easy to get started with that would drastically decrease my development time, or do I already have everything I need?
Thank you for your time
-MK Hokie

1. Your hardware and software look appropriate assuming the motors are compatible with the 9505s. You didn't mention the NI SoftMotion module in your software list which is something you will need.
2. There are a few ways of doing this. One method would be to have a force PID loop that would attempt to maintain a force setpoint by directly outputting values to your torque loop. In this case, the drill would essentially move as fast as it could while maintaining the force setpoint. Another option is to have the force loop output a velocity setpoint. You would then have a velocity PID loop that outputs torque values to the torque loop. By adding this additional velocity loop you could have control over your maximum and minimum velocities. There are likely other alternatives as well, but these are the first two that come to mind.
3. Unfortunately there are no shipping examples that close the loop on force feedback. My advice would be to start with the NI 9505 shipping example and adapt it to your needs. There are quite a few things you will want to change though. Do you know if you will need to use the trajectory generator to move the drill into position before starting the force control?
Assuming you don't need any trajectory generation, you can scrap the entire RT portion of the NI 9505 example and just create the necessary FPGA code. On the FPGA, you won't need the Spline or Synchronization code either because this information would no longer be coming from RT. You could take these out and replace the position loop with a force loop and possibly a velocity loop and your FPGA program would basically be finished. In fact the only real motion IP that you will need is for the encoders (assuming you want velocity control) and PID. Then you would need to create an RT VI that allows you to send down enable, disable, PID gains, and setpoints.
If you do need trajectory generation, you would want to keep most of the example code the way that it is, but then program in a 'Force Mode' that utilizes the force and velocity controly as described above. You could think of it as having two different routines programmed side by side.
Regards,
Burt S

Closed loop configuration question

I have a motor(with encoder feedback) attached to a linear actuator(with end limit switches).
The motor has a commercially bought servo drive for control.
The servo drive will accept either a step/direction (2 seperate TTL
digital pulse train inputs) or an analog -10 to 10vdc input for
control.
The purpose is to drive a linear actuator(continiously in and out) in
closed loop operation utilizing a ( (SV) Setpoint variable)value from a
file converted to a frequency to compare with an actual ( (PV) Position
variable) measured frequency.
I have created and experimented with individual vi's allows analog
control and digital pulse train control (thankfully with the help of
examples).
Before I pose my question, I would like to make the following
observations: It is my understanding that Closed loop control
means that I dont need to know an exact position at which to drive, but
constant comparision of PV and SV through PID applictation.
Without getting into any proprietery information I can say that the
constant positioning of the linear actuator will produce a latency of 2
to 3 seconds based on the time the actuator moves to a new position and
when the PV will change. While experimenting with the analog
input, i noticed imediate response to motor velocity, but after the
motor is stopped, position is not held in place. However, while
experimenting with the Digital pulse train input, I noticed that the
servo drive can only accept one command at one time; if, halfway
through a move, position error produces a response to move the linear
actuator in the opposite or different direction, the origional move
must finish first.
Can anyone recommend the proper configuration for the closed loop control i have described?
If I can make the system work with the servo drive/motor I plan to use
the simple (pci 6014) daq card with the Analog out, or utilize the
digital out.
If I cant get this to work, we do have a pxi with 7344 motion card(I
would like to exhaust all efforts to use the PCI 6014 card).
Depending on where I go from here, I planned to use the PID vi's for the loop control.
Thanks,
Wayne Hilburn

Thanks for the reply
Jochen. I realize there is a built-in latency with windows but I
think the I/O control would be ok. A change in actuator position
will not result in an immediate change in process variable; Is
there a way to measure the latency or is it calculated? A
satisfactory reaction time could be from 1 to 1.5 sec.
Use of the PCI-6014 is to supply the control output to the servo
drive/amp, and not to drive the motor itself. As stated earlier,
while using the 6014 board, I have the choice of digital or analog
output.
Currently I am at a point where I must choose which configuration,
analog control or digital control(in the form of digital pulse train),
(i am inserting from first message)
While experimenting with the analog
input, i noticed imediate response to motor velocity, but after the
motor is stopped, position is not held in place. However, while
experimenting with the Digital pulse train input, I noticed that the
servo drive can only accept one command at one time; if, halfway
through a move, position error produces a response to move the linear
actuator in the opposite or different direction, the origional move
must finish first. .
I dont claim to understand all the limitations with the
specific boards, however, i am using an approach that is showing me the
characteristics(a couple are listed in the above paragraph) of
the hardware and software configurations.
So I am really back to my origional question; Which configuration
would be better for closed loop control, analog or digital pulse train?
Thanks,
Wayne Hilburn

Closed Loop or Open Loop

Dear All,
I'm currently using the DAQ card PIC-6221 to control a DC servomotor with an encoder displacement feedback. I'm using the labview program with a motor amplifier to start the motor and stop it at a specific rotational displacement, where it works by stopping the motor when the encoder feedback value reaches the input desired displacement value. The final displacement of the motor before it stops always exceeds the desired value marginally. May I know for my case,am I using an open or closed loop control? Is a PID controller a MUST for closed loop control? Is my DAQ card capable of desigining a PID controller? If so may I know how?
Also, my project requires me to toggle between the current and voltage mode control. May I know if that is possible to carry out digitally using the Labview Program as my current motor amplifier requires me to push a switch manually to toggle between Voltage and Current mode. Finally, I hope my last question is not out of this world but is it possible to use 2 amplifiers(drivers) for a single motor such that there's a chance to use both the current and voltage modes of control?
Really looking forward to the replys of you kind souls out there! Thanks!
Regards,
Oompa

Oompa,
to learn more about the general concepts of motion control, please visit this link.
In general I widely agree with JB's suggestions. I'll just add some more comments to your questions.
If you need closed loop control depends on what you try to accomplish. If you just want to generate a certain torque (current mode) that is proportional to the output voltage of your control device, you may not need to run a closed loop system. A similar statement is true for the voltage mode.
Closed loop control is especially important if you need to control the position, or if you need to run a special trajectory profile (position/velocity/torque over time)
Maybe it's possible to control the current/voltage mode of your drive with a digital signal. You will have to find out in the manual or check with the vendor.
Using two drives with a single motor doesn't seem to be recommendable. If you want to do something like that, you will need to switch the power signals with relays between the two drives, but as you are working with inductive loads this might become quite tricky and there is a risk to burn both, the motor and the drives...
Regards,
Jochen Klier
National Instruments

FTP closed loop in directory

I did set up the FTP Service in OSX.4.9 server
The directory path is defined as /server/data, where server is a directory on root level
Connecting with a FTP client there is not presented the data directory, but the parent directory "server"
I can navigate to "data" but when I open it, I am again in "server"
and so on.
Any hints?

yes, for each closed loop control, you need a separate PID.vi. However, the vi is normally set reentrant, so you need 10 instances of the vi.
For you application, if the nature of the problem is
1) more voltage implies more heat and hence higher temperature,
2) and a certain voltage setting is expected (with some variation) for a certain temperature set point
you probably need a PI control (the D parameter is set to zero, or barely large enough to control the speed of the control)
Once tuing is done, yo either default the parametrs of each loop or save them to a data file (my choice) that is normally read and loaded when the software is run

Can the USB NI DAQs be used for process control,eg.closed loop? or is too fast

can the USB NI DAQs be used for process control,eg.closed loop? or is too fast.

Hi mho,
1.usb is very high speed that is correct.Better you can choose PCI DAQ.But thats upto you.
2. see this:-
http://sine.ni.com/nips/cds/view/p/lang/en/nid/14136
3.If Matlab support TCP/IP, that could be an option.
see Another idea: http://digital.ni.com/public.nsf/allkb/244A37667BD7CBCE86257520007F937B
Another simplest way to do it (assuming you running Windows) is to use a Matlab script.
If both programs running on different systems:-
Most simple and slow - Create two VI's with shared variable on both machines, and use a matlab script to
share data. (this makes matlab some kind of "slave").
More advanced but still relatively slow (Create two VI's with shared variable, on the Matlab machine build the .NET
dll, and it can be used on Matlab too ( at least at 2010b version, earlier version support only COM).
Create TCP/IP connection between two comps.
There is "out of the box" NI products, that communicate with Simulink models.You please do a simple search on that...OK
I think this link is also helpful for you:-
Procedimiento para la interface entre LabView 2009 y Matlab 2009b.pdf 1128 KB
Anyway All the best.Try....do it.
Thanks as kudos only

NI 9505 Closed Loop Position Control Example

Hello, I have a cRIO 9073 with a NI 9505 module that I'd like to use for simple position control of a unit along a lead screw.
I don't have the softmotion module, and am trying to write a program bassed off of the "Position Control (closed loop) - NI 9505" example to control the position the small motor attached to the lead screw (Faulhaber 2342S024CR with a 512 count/rev encoder that we had laying around)
I've reviewed the manual PID tuning example, and have not had much luck getting the response that I'd like when making large position moves simply by adjusting Kp,Ki,Kd gains of the position loop, as the overshoot remains too high for this application when making large moves. The system is also oscillating about the set point, and doesn't ever seem to dampen out unless I change things other parameters on the fly such as the current limit, or current loop parameters (osciallations get worse as current limit is increased).
Can someone advise me if the components of this example are up to this task? Or on the interactions between the current limit, current loop parameters, and position loop parameters from this example, and which parameters would have the most impact on achieving desirable system performance?
Is there a VI available that can autotune such a motor?

Hello - there are many reasons why a closed loop controller can oscillate - from correct settings of controller (kp,ki,kd) to making sure signals act in the appropriate direction to deadband/friction in the actuator to badly sized signals/actuators.
Firstly, have a look at the signal your controller is outputing (ideally in LabVIEW so you can graph it). Does it oscillate - perhaps as a sawtooth, a sinewave or simply switching between maximum and minmum values. I presume the electrical motor driving the screw which is driven from some AO signal from the cRIO (could also be a PWM signal driving the motor).
I expect (from what you say about current limit) the control signal will be oscillating by switching between maximum and minimum (e.g. +10V to -10V) or oscillating like a sinewave. What values of kp, ki, kd are you using ? If kd is non-zero, set it to zero (you only need worry about this if you want to get maximum performance). Is ki non-zero ? Try setting it to zero - any better ? If you are still getting big oscillations in your control signal, keep reducing kp (e.g. half each time?) until oscillations disappear (as you reduce kp, control signal *should* get smaller - maybe not straight way though).
If this does not make oscillations go away, then it may be that you have a sign wrong in your loop - i.e. a positive control signal makes lead screw move in opposite direction controller expects. This should be a fundamental thing sorted out when setting up the loop - you could do an open test to check which way +ve voltage moves lead screw. If you find it moves in opposite direction - you can either re-wire, or put a "-1" gain on controller output.
If there is any more subtle oscillations / obersvations, then try to show some plots of the lead screw motion and control signal, as that always helps when trying to diagnose what is going wrong.
Good luck.
Consultant Control Engineer
www-isc-ltd.com

How to create a step loop control in a screen

Hi,
Basically, what I need to do is to create a fully dynamic screen. I want to send the structure name and the fiednames and the function will create a screen will all the required fields.
I explored many possibilities and the best one seems to be using the step loop control in a screen. I know, this is really old technology but I do not care as long as this work great !
I saw that the function group MASSFREESELECTIONS is doing it, this look pretty simple, fast and fully dynamic...
My only problem is that I'm not able to create a step loop control in a standard screen.... is it an obsolete function that was removed from the control list ?
Thanks
Dany
Message was edited by:
Dany Charbonneau

Hi,
STEP LOOPS
Step Loops are type of screen table . Step loops are repeated blocks of field in a screen. Each block contains one or more fields and these blocks are repeated. Step loops arent like actual table. You can scroll vertically but not horizontally. Three steps are associated with creation of step loops:
Creation of step loops on screen, which includes declaring fields on the screen and then defining the step, loops for these fields.
Passing data to the step loop is exactly similar to the passing of data to table controls.
In step loop, you dont need to define the step loop as such in the module pool program but the cursor needs to be defined in the program.
Types of Step Loops
Static Static Step Loop (SSL) have fixed size that cannot be changed during the runtime. If user resizes the window, the size of the static step loop is not changed.
Dynamic Dynamic Step Loop (DSL) is variable in size. When the user resizes the window, the system increases or decreases the number of the step loop blocks.
You can have only one dynamic step loop and can have as many static loops in your transaction.
Programming with the Static and dynamic step loop is exactly same. For the system or for the user it doesnt make any difference whether it is static or dynamic step loop. Only attribute, which you fix during designing of the step loop, is type attribute for step loop F for fixed i.e static and V for variable i.e. dynamic.
Writing code for Step Loop in the flow logic.
PBO.
Loop at itab cursor cl.
Module set.
Endloop.
PAI.
Loop at itab.
Endloop.
Empty loop is must for both table control and step loop
LOOP AT statement for step loops and Table controls is similar. Loop At statement transfers the data to screen table. You need to have the Module to assign the values for the screen table.
In module pool program you need to define the cursor.
Date: CL TYPE i.
Cursor parameter tells which line of step loop display should start.
Module Set in module pool program assigns the values to step loop fields, which is similar to table controls.
Refer to this program <b>DEMO_DYNPRO_STEP_LOOP</b>
hope u can get some idea about table control & step loop in this line.
http://www.sapfans.com/sapfans/repos/comelite.htm
Check this link,
http://help.sap.com/saphelp_erp2004/helpdata/en/9f/dbac1d35c111d1829f0000e829fbfe/frameset.htm
<b>Reward points</b>
Regards

Problem using PID toolkit and control design toolkit to design the closed loop system. (for DC motor closed loop)

Hi, i have facing some problem during i upgrade a project. This project is an opened loop system, it only achieved up to controlling the speed of motor, detecting the speed of motor, and switching the direction of motor while controlling the motor (This motor is a 12 VDC motor).
In order to improve the project, closed-loop dc motor control system will be implemented to correct the error of the motor's speed and maintaining the speed for the initial setting. I would like to use PID control method to do the closed loop system.
I already installed the PID toolkit V8.2 and control design toolkit V2.1.2, and i'm using DAQ usb 6221, LabVIEW 8.5
Below is my problem.
http://img177.imageshack.us/my.php?image=howtocreatethesetpointnx2.jpg
question: 1. How to generate a icon for set point? my setpoint is duty cycle...
2. How to feedback the output duty cycle to summing junction?
below this is my basic concept
http://img237.imageshack.us/my.php?image=closedloopbz5.jpg
Problem 2:
http://img357.imageshack.us/my.php?image=problem1yk2.jpg
question: Why PID toolkit icon cannot wire to cd series.vi?
Below is my original program...
http://rapidshare.com/files/140538836/pwm_generate-final_PSMII.vi.html

Hi Cyrus
Have you had the opportunity to see our
developer zone site on the PID toolkit? This article also has sample
code at the bottom that may help you in developing your application. I
have also linked below knowledge bases regarding setting a point
profile and generating a PWM from a digital output line.
PID toolkit
http://zone.ni.com/devzone/cda/tut/p/id/6440
How to generate a set point profile:
http://digital.ni.com/public.nsf/allkb/125F27AC143B6AFD86256C2B0004A4DC?OpenDocument
How to generate a PWM on a digital output line:
http://digital.ni.com/public.nsf/allkb/1561D31534F07D608625727900391114?OpenDocument
Thank You
Eric Reid
Thank You
Eric Reid
National Instruments
Motion R&D

Dual loop control for positioning system.-- motion ocntrol

I am currently doing a dual loop control for a positioning system, i use the tachometer to read the velocity and the position encoder about the position of the platform.
the problem i am currently encounter is that i am not sure weather the computer have the PID toolkit, because i can not find them under the control design and simulation module. so i did a PID use the basic labview functions, related information is in the attached documents.
i am not sure about the dt part, did the labview have this kind of function like to calculate the simpling time??
do i have to install the labview real_time potion? i am right using the labview 8.5
another question is that, how i am going to let the system remember the position instead of return to 0 every time i restarted the program? otherwise is there any other way that i can command the motor to move to the target position which is initially defined?
the last question is that that is it possible for me to generate a profile regarding the current and the desired position? to set a maximum velocity and acceleration.
i do not have a motion controller, so i did not install the motion and version module.
can some one suggest me a way to do this?
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attached is the files.
Attachments:
Integral.vi ‏8 KB
Dt.vi ‏7 KB
A CLOSED-LOOP TEMPERATURE CONTROL SYSTEM.pdf ‏886 KB

How do I simulate thermocouple in closed loop PID using plant simulator?

Hi all
am creating a PID application to control temperature which is measured by a thermocouple. how do i simulate the thermocouple in closed loop by changing the plant process parameters, the temperature is controlled by a infra red lamp.
Regards
Arun

Hello Arun,
Please refer to the second order system that I have attached. This VI uses the plant simulator to simulate a thermocuple in a temperature chamber.
Regards,
Arun V
National InstrumentsMessage Edited by sunrays on 06-27-2005 06:21 PM
Message Edited by sunrays on 06-27-2005 06:22 PM
Attachments:
Angelantoni.zip ‏31 KB

Creating a simple closed loop control

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