How to measure torque on a DC motor using Multisim?

Hello,
I would like to know how we measure torque on a DC motor using Multisim Education edition.
I've searched for the component, "eddy current load brake", but could not find it. Is that component in Multisim?
Thank you,
Neil

Hi,
Please refer to this forum post.
http://forums.ni.com/t5/Circuit-Design-Suite-Multisim/PM-DC-Motor-Model-Trouble/td-p/1931859
Hope this helps.
Regards,
Tayyab R,
National Instruments.

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Dear Experts,
i want to plot a speed torque characterstics in labview using ni hardware with servo motor.
please suggest me complete solution for this above question

Torque specifications should be available from the motor manufacturer. I'm not aware of a standard way to measure torque vs. speed, but maybe a google search would turn something up. Here's what I found.
Good Luck
Adam

How to measure current on DC servo motor.

Need to measure current on DC servo motor. What is the best way to measure the current on the motor as it moves to position? Using PXI-7344 controller and MID-7654 drive unit.

This is not an easy task. Here are some ideas:
Direct current measurement:
Add shunt resistors into the motor cabling and measure the voltage over the resistors. As the 7654 doesn't provide DC current but PWM current (32 kHz) you will have to acquire the data pretty fast (at least with 200 kHz). This could be done with a DAQ-board like the PCI-6220. Additionally you will have to do some math to calculate the RMS value of the current.
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How to control steps of a step motor using labview?

Hi, I'm really beginner on labview and I need to make a VI to control a step motor. For each n steps, a sensor must observe the position of a mechanism and save in a table based on the number of steps taken. I've already have the sensor's driver, but I don't know how to comunicate labview with the step motor.
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I need to measure high currents accurately. I have only a FPGA board and TBX 68 terminal block. Do I need any other NI hardware?

The answer will depend on your specific situation, such as the voltage levels you are working with, the source of the current, the influence some additional components such as a shunt resistor may have, etc. Can you provide more details about the application, the source of the current, the voltage levels, how quickly the current will change, the stimulus for a current change, etc.
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This is probably the simplest approach. If this setup is not feasible (e.g. the voltage in not within the 7831R input range) then you will need some additional signal conditioning. There are some off-the-shelf components for measuring larger currents that would translate the current into a voltage that you can measure with the FPGA board. Look at the following component as a place to get started.
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http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=102&M=SCD20PUN
Christian L
NI Consulting Services
Christian Loew, CLA
Principal Systems Engineer, National Instruments
Please tip your answer providers with kudos.
Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system,
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How to do Torque mode(position-velocity disabled)using 7344 & torque xdcr signal to 7344 ANI chan ?

Seeking advice on a preferred method to do a torque control application using a PXI-7344, a brushless DC servo motor, digital servo drive/amplifier, a torque transducer as the feedback device connected to one of the 7344's analog input channels.
I have several torque testing applications and would appreciate comments from anyone who has done torque control using NI Motion.

There are really two ways that this can be accomplished using the 7344. It can be done manually by reading the value of the ADC and then outputting a corresponding value on the DAC. This is all done in software and is not as fast as the onboard PID loop. This method could also be implimented with a DAQ card.
The second method would be to set the Primary Feedback for that axis to the correct ADC Channel. Since the ADC is 12 bit, this maps the axis to -2048 to 2047 in counts. Then you could tell the axis to move to a certain target position in counts and it would actually be a torque target value, not position since counts is now in torque. I have not done this but theoretically it should work, however tuning the system may be problematic depending on it's linearity
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Many thanks in advance
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Hi ZYuan,
To measure the frequencies simultaneously, you would need to duplicate the code for the single counter example twice and link the error cluster from one set to the next. I don't have a specific example but the following example can be used as a guide.
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http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DC9F56A4E034080020E74861&p_node=DZ52325&p_source=External
Hope that helps. Have a good day.
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Hello everyone,
I have a solar panel, controller, battery and load. I need to measure their voltages and currents.
The tensions are higher than 10V DC.
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thank you

In the past, we've used simple resistor dividers. More recently, we added op-amps to the circuit so that the DAQ impedence didn't mess with our signals. But the simple resistor dividers work just fine.
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Frequency measurement using multisim

Hi all
i'm new to multisim and i want to ask about how can we measure frequency of analog signal(ecg) using multisim oscilloscope
I will be waiting for you reply
thnx

Hi Rahul,
OK, for a bandpass filter, you should use the AC Analysis under the Simulate menu. Another method is to drag a Bode Plotter and connect it to your circuit.
For the AC Analysis of the filter respnse, this following link might help you.
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http://www.ni.com/white-paper/12690/en/
NI Multisim: AC Analysis frequency response
http://www.youtube.com/watch?v=tgCPDBtRcso
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MultiSim Bode Plotter
http://www.circuitsmadeeasy.com/index.php?option=com_content&task=view&id=105&Itemid=74
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National Instruments
Attachments:
14Pin_Chip.ms13 ‏87 KB

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I don't see anything wrong with your approach; however, I'll throw out a few thoughts:
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How to measure the baseline of a noisy, pulsed signal

Hi
I am measuring the torque exerted by a large motor on a shaft using a load cell and lever arm. The shaft runs at approx 150 rpm. I have attached a drawing that shows the output I get. This is a test rig.
I have written some code that measures the maximum peak out of a group of approx 5 peaks and writes this to a shift register. This gives me an idea of the maximum torque "spike".
I also wish to measure the baseline torque (due to the bearings in the machine). Even when highly filtered (my noise filter is set to 49Hz) the signal exhibits this noise which is probably due to vibration in the system. The signal is zeroed when the motor is not running.
Does anyone have an ideas on how to measure the "baseline" torque? The large spike in torque prevents me from doing a running average. Can anyone think of a way of averaging just the noisy part of the signal to get an average value? I aim to to subtract the average baseline torque from the peak value to get an idea of the torque due to the event which causes
the spike.
Any help would be greatly appreciated.
Many thanks.
Attachments:
drawing of torque signal.gif ‏26 KB

Thanks for the reply. I understand what you are saying. However, I might have to modify my method for measuring the peaks if I choose to implement your idea. I have taken a screenshot of my "peak finder" code and attached it.
Bascially, the reset terminal is wired to a timer which outputs a pulse every few seconds. This resets the vi (a standard NI one I think) and sets the peak magnitude back to zero. This way, I am windowing the signal and measuring the maximum peak in every window. This is what I need to do.
So I could use a logical filter to feed data to the running average only if;
the amplitude of the signal is less than a certain threshold
and if the current value has similar low peaks either side of it
How would you construct the code to delay the evaluation so that the values in front and behind of the current data point can be analysed?
thanks again
Attachments:
peak_find_screenshot.jpg ‏45 KB

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I need to run bipolar stepping motor using LabVIEW 6.1. Would anyone please guide me how to do that.
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Hi,
I am developing a data acquistion and control system for an engine dynamometer using the fieldpoint modules and Labview. One of the most important signals is the engine speed, measured in RPM. The RPM signal is a 0-12V pulse where one pulse equals one revolution of the engine. As well as being an important piece of data for later analysis, engine RPM will also be in the input into a PID controller, so the signal must be both accurate and have a high measurement frequency.
Currently I am using the FP-CTR500 modules to measure the frequency of the signal. I am already aware of the included frequency measurement VI example, as well as the one posted before for low frequency measurements, and I have gotten both to work with my setup. I would be using the low frequency VI becuase the max frequency measurement would be in the 200Hz range.
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2321
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I can post my VI if this help.
Thanks,
Huang

Thanks for your reply.
I should probably describe my current setup before I go into anymore details with the problem. As for my specific setup, I am using an FP-1000 connected with an AIO600, AI110, CTR500, and TC120 all running through the RS232 line to a desktop running labview 8. The actual counter module is reading a tachometer signal output from a separate engine controller. THe output is a 0-12V ON 50% duty cycle signal. As for data logging, i am simply using a "write to measurement file" Express VI. I have a while structure which holds all of the express VIs which access the fieldpoint IO, and these are all routed to the "write to" VI.
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I was able to solve the problem of calling the frequency variable from the case structure by using a local variable which is called outside the case structure.
And now I have been having a lot of problems with reading the actual frequency from my engine controller. THe actual signal will only range from 0 to around 200Hz. I noticed, by comparing the actual signal to what was being read in my labview program, that after around 80Hz the signal increases by around 1.5times more than the actual signal. ie. Actual signal = 100hz, Read Signal = 150Hz. After trying to figure out what was the problem, I decided to change the Noise Filter settings to 200Hz. It actually worked for all the frequency ranges up to around 150Hz but after that the filter attenuates the signal to the point where the actual signal is 160Hz, but is being read at 100Hz. My question is if there is a way to change the actual filter setting outside of the 2 given setpoints (200hz and 40khz) or if you have any other suggestions on how to fix this problem? I was thinking of creating a noise filter input in MAX so that i could play with the values in Labview, but am i only limited to those two filters?
Thanks again for your help,
Huang

How to measure the performance of Extractor

Hi,
How to measure the time taken to by the extractor when executed from rsa3 for a given selection?
Lot of threads speak about ST05... but these transactions are too granular to analyse.
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Thanks,
Balaji

Maybe SE30 can help you....
Regards,
Fred

How to measure the performance of sql query?

Hi Experts,
How to measure the performance, efficiency and cpu cost of a sql query?
What are all the measures available for an sql query?
How to identify i am writing optimal query?
I am using Oracle 9i...
It ll be useful for me to write efficient query....
Thanks & Regards

psram wrote:
Hi Experts,
How to measure the performance, efficiency and cpu cost of a sql query?
What are all the measures available for an sql query?
How to identify i am writing optimal query?
I am using Oracle 9i... You might want to start with a feature of SQL*Plus: The AUTOTRACE (TRACEONLY) option which executes your statement, fetches all records (if there is something to fetch) and shows you some basic statistics information, which include the number of logical I/Os performed, number of sorts etc.
This gives you an indication of the effectiveness of your statement, so that can check how many logical I/Os (and physical reads) had to be performed.
Note however that there are more things to consider, as you've already mentioned: The CPU bit is not included in these statistics, and the work performed by SQL workareas (e.g. by hash joins) is also credited only very limited (number of sorts), but e.g. it doesn't cover any writes to temporary segments due to sort or hash operations spilling to disk etc.
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Note that "statistics_level=all" adds a significant overhead to the processing, so use with care and only when required:
http://jonathanlewis.wordpress.com/2007/11/25/gather_plan_statistics/
http://jonathanlewis.wordpress.com/2007/04/26/heisenberg/
Regards,
Randolf
Oracle related stuff blog:
http://oracle-randolf.blogspot.com/
SQLTools++ for Oracle (Open source Oracle GUI for Windows):
http://www.sqltools-plusplus.org:7676/
http://sourceforge.net/projects/sqlt-pp/

How to measure torque on a DC motor using Multisim?

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