Shaker Synchronized Serial Acquisition Template (with NI-DAQmx)

The control palette provides buttons for controlling the flow of the program. Specifically we have:

• Configure Aquisition - this will make the Configuration tabs of the other two palettes active so that the user provide experimental information.
  • The "Start" and "Stop" buttons below this can be used to run and terminate the experiments respectively.
• Live Signals - this will open up the "Active Nodes" and the "Live Signals" tabs in the other two panels respectively.
• All Data - this will open up the "State" and "Recorded Data" tabs in the other two panels respectively.
• Frequency Responses - this will open up the "State"and Äveraged FRFs" tabs respectively.
• Nyquist Graph - this will open up the "Nyquist Range and Cursor" and "Nyquist Plot" tabs.
• The Help button opens up this page.
• The Delete Data… button opens up a prompt asking which data to delete from current acquisition.
• The Exit button exits the VI application .

The data palette has 5 tabs:

1. Configuration: Set the file names to save here. Controls are also provided for FRF averaging and windowing parameters.
2. Active Nodes: This lists out the node that is taken as reference along with the nodes that have been taken as responses. It also indicates the number of averages that have been completed for the FRF analysis. (see fig. 2).
3. State: This lists out a summary of the data that is current stored. This allows one to choose which of the saved datasets to visualize, etc. (see fig. 3).
4. Nyquist Range and Cursor: This lists out parameters helpful for the Nyquist plot visualization (see 4).

The display palette has 6 tabs. The last tab, named "Scratch Space", is merely for development purposes and can be used for monitoring the program. Other than this we have,

1. Configuration: (see fig. 1) Provide all the information necessary for conducting the tests.
   • The "Reference Channel" is used for the FRF estimates.
   • The "Control" cluster sets the parameters for the control.
     • If Type is set to None, then each realization of the random excitation is repeated as many times as Dwell Blocks (4 by default) and the response to the last one is saved.
     • If Type is set to RMS, then a channel must be selected along with a target RMS (in its own engineering units). The tolerance signifies how close we need to come to the target to deem the responses as converged. Max Iters specifies the maximum number of iterations to look for convergence (each iteration involves dwelling before update).
       • A secant based update is employed for the "solve".
   • The "Excitation" cluser sets the parameters for excitation.
     • If _Type is "Uniform Random", then the excitation is chosen by taking voltage values between -Amplitude and +Amplitude .
     • If Type is "Gaussian Random", then samples from a Gaussian distribution with zero mean and "Amplitude" standard deviation are provided.
     • If Type is "MultiSine Random", then the excitation is a band limited multisine periodic random signal with the band to be selected in the "Frequency Range (Hz)" control below it.
2. Live Signals: Merely plots out the reference as well as all the channels as they are running (without requiring convergence, just for visualization).
3. Recorded Data: Plots the recorded data in the time domain (different sets can be chosen in Data Palette->Active Nodes) .
4. Averaged FRFs: Plots the averaged FRFs along with Coherence and Phase.
5. Nyquist Plot: Provides the Nyquist Diagram.