Need Help With my Blood Pressure Monitor VI Please!

[VeronicaL]

I am building a blood pressure monitor as well.  I have so far an Iworx, DAQ board and am measuring blood pressure using cuff pressure.  So far my VI shows the original signal in a graph and I have two more graphs which separate the DC signal and gives an AC signal of the oscillations using a bandpass filter.  The next step I'm having trouble with is displaying what the systolic and diastolic pressures are from my AC signal comparing it to the DC signal and hopefully getting the pressure value out of it.  My graphs are all on autoscale because that's the only way I could get my signal.  So, I don't have the blood pressure values correctly displayed.  It's an inverse signal because of the cuff.  How do I combine my DC and AC signal into one graph to show the actual blood pressure values into a graph.  I've been dealing with peak detectiona and arrays and have attached a copy of my VIs and images of what i'm trying to get.  Please help me.  I have senior project on Wed. June 11 and need to have this completed by Monday, at most.

P.S.  I am trying to get my array of locations and convert them into time locations so I know the values of the peaks on my AC signal.  The equation given is (t0 + dt * locations) = time locations  I don't know what to do...please help

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Message Edited by VeronicaL on 06-07-2008 02:13 PM

Message Edited by VeronicaL on 06-07-2008 02:17 PM

[Wallace_F]

Hi VeronicaL,

You can combine your AC and DC signals for display on one waveform graph by using the Merge Signals function which you can find in the Express>>Signal Manipulation palette of your block diagram. The AC and DC signals will be the inputs, and the output should be wired to a waveform graph.

Properly displaying two waveforms of different ranges on a single graph can be tricky.  I recommend disabling auto-scaling for both the x and y axes, and manually setting them so that you can select the range of signals that you want to see. To select the minimum and maximum y values, simply disable auto-scaling for the y axis, and then double click on the maximum y value and type in the value that you wish to specify.  Do the same for the minimum y value. The last thing I would recommend is to make the graph palette visible so that you can use the zoom in capability. To do this, right click on the waveform graph, select Visible Items, and put a check next to Graph Palette.

To convert your Locations array to the Time Locations, you can create an array of equal length and simply multiply the two arrays.  The first entry of the array should be t0, the second should be t0 + dt, the third element should be t0 + 2dt, etc. This will only work if dt is a fixed value.  I’ve modified the VI that you included in your forum post to illustrate what I’ve posted in reply.

Best wishes,                                                                                                                                                                                                        

Wallace F.