Acquiring EMG signal in real time using cRIO9073 and NI9201

[Illa]

Hi

i am aquiring emg signals through instrumenattion amplifier to cRIO,i am using scan mode for aquiring signals ,i am able to see the changes but not in real time a slight time gap is there,please help me ragrding this,and moreover on the x axis the signals start from 0 and it goes on, when i stop my vi i want to check  the signals from 0 on waveform chart.

please guide me regarding the above two issues.......

[Steve.J]

Hi illa,

Scan mode is not intended for doing waveform acquisition - it is really meant for simplifying the use of the cRIO system when you only need to do single-point read and writes to I/O channels at moderate rates...maybe a few hundred Hz.  For waveform reads, you should setup the cRIO system in the normal mode which requires you to use the LV-FPGA module to develop a VI that does the acquisition and then develop a LV-RT program that runs on the controller that reads the waveforms (arrays) from the VI running on the FPGA.  This is a very simple cRIO application to develop and you should be able to find example programs that you can build on.

Start here to get an overview of the process:  http://zone.ni.com/devzone/cda/tut/p/id/8167#toc1 - look for the video titled "Creat Custom Hardware with LabVIEW FPGA for High Performance Applications".

Steve

[Illa]

1)Ok sir i did FPGA programming for acquiring signal  but still i couldnt get  the signal sync when i  apply force on muscles. please look in to my attached VI's.

2)after creating  FPGA VI we deploy in to cRIO and we create FPGA host for running code our code,once FPGA Host is created do we need to run both the VI's or only FPGA Host is  sufficient.

Please help me regarding this

[ZJ.Gu]

Hi illa,

What's the real problem? Could you please have some screenshots?

Thanks!

ZJ Gu

[Illa]

1. sir,i am attaching my code screen shot (actually i modified the example program ),but  I  couldnt know why sampling rate  is used when i dont need sampling ( the block i higlighted in my screen shot with red colour )are using.please tell me what parameters i need to assign for AI sampling rate and software loop time. if i need to see the changes in EMG waveform according to my muscle variation.

[ZJ.Gu]

Hello,

Can you please not connect to filter and just wire out to a waveform graph or chart to see whether the analog input is right? and what is your front panel showing? I am afraid that you just wiring one point to a Filter block will pose some problem.

Thanks!

ZJ Gu

[Illa]

i am attaching my front panel graphs .

and also  i tied connecting  my AI directly to garph which you told me to do but i couldnt connect i am uploading those snapshots

please guide me where i did mistake i want to do filtering and rectifieing in real time and want to caluclate RMS with that RMS i need to do comparison wih some threshold value and enable the Motor,My Hardware set up with Driver(LM293D) is ready,which i connecetd it to Ni 9401 but i am stuck with this EMG aquisition and enabling 9401 digital ports as output.

[ZJ.Gu]

Hi,

From your pic, it doesn't look like a muscle contraction. Did you acquire the signal when a muscle contraction happens? And for the software loop 100ms, it means you only read the AI every 100ms. That is only 10Hz. For EMG, usually you should use 1K ~ 5KHz or above. Try to change your software loop time and the AI sampling rate.

I think this could be a good call support. You could call your local NI support. I think this will give you prompt response and guide.

Thanks!

ZJ Gu

[Illa]

i changed the software loop  time and sampling rate now it is working and i am able to see the variations in my raw signal when i contract and relax,but you told me there is aproblem with my  filter even i am unable to get time axis syn with my raw data and filtered data.please help me how to over come this problem,

i am attaching my snapshot of obtained EMG  rawsignal and my  block diagram,please let me know wheather my EMG is correct or not. and also i want to calculate power spectrum,when i connec my raw signal directly to spactral VI,there is no output in the graph .

[Illa]

i changed the software loop  time and sampling rate now it is working and i am able to see the variations in my raw signal when i contract and relax,but you told me there is aproblem with my  filter even i am unable to get time axis syn with my raw data and filtered data.please help me how to over come this problem,

i am attaching my snapshot of obtained EMG  rawsignal and my  block diagram,please let me know wheather my EMG is correct or not. and also i want to calculate power spectrum,when i connec my raw signal directly to spactral VI,there is no output in the graph .