FAQ: ADIS16228/PCB-ADISUSB Tutorial

Q:

How can I use the ADIS16228 evaluation tools to determine if this product meets my performance needs? 

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A:

This post illustrates an experimental approach of observing the vibration signature associated with a example system, using the ADIS16228 and its evaluation tools. In this example, we decided to find out if we can use the ADIS16228 to determine the operational state of a compressor, which produces cold air in a temperature control chamber. For this compressor, there are three different states, which appear to have different vibration profiles: OFF, IDLE and ON. The combination of the ADIS16228/PCBZ, ADISUSB, a laptop and the ADIS16228 evaluation software provided a convenient platform for analyzing the vibration on the compressor's enclosure. Since we didn't want to drill holes in the enclosure (at least to start with), we attached the ADIS16228/PCBZ to the top side of the enclosure (in the middle), using double-sided tape.  In order to minimize the mass of the sensor, we used a 6" ribbon cable to connect the ADIS16228/PCBZ (J1) to the ADISUSB (J1), as shown below. For complete setup guidelines, please see the ADIS16228-ADISUSB User Guide Wiki. 

Once we secured the ADIS16228/PCBZon the surface of the enclosure, we plugged the ADISUSB in to the PC-USB port and opened the ADIS16228 Evaluation Software package. Under Main Control, we established (or verified) the following settings:

• Click on Interface, then on USB, to make sure that the board was connected.
• Under Main Control, select Manual for the Rec Mode
• Under Main Control, select Hanning for the Window
• Under Main Control, select None for Storage Options.
• Check the box for Auto Plot
• Under Sample Rate, make sure that the check box next to SR0 is selected and that the check boxes next to SR1, SR2, and SR3 are not selected.
• Keep FFT AVGs equal to 1 and the Range equal to 0 to 20g.
• Click on Null and wait ~1 second for it to complete
• Click on Start, which will trigger data collection, processing and a plot.

The following plot showed us that there appears to be vibration, but at levels that are much lower than the 20g range.

After reviewing this plot, we clicked on the Scale(g)button to scroll down to a range, which better represented the FFT data.

After observing that the peak vibration energy was at lower frequencies, we changed to the the Sample Rate setting of SR1 and selected a Range of 0 to 5g for this Sample Rate. From the following plot, we can observe the impact of finer frequency resolution.

We also experimented with using a Sample Rate setting of SR2, a Range of 0 to 5g and 8 FFT Averages, in order to reduce some of the variation in the vibration signature. Again, after all settings were complete, we hit Startto trigger the capture/FFT analysis process. In the plot, we observed a large peak at bin 193, which was ~0.1288g (see marker).

Using the same settings, we put the compressor into IDLE mode and ran another FFT (observed a large change in the peak energy. As we can see, the energy at bin 193 was greatly reduced. From this information, we have a clear difference in FFT signature, between the ON and IDLE states.

In order to find a signature difference between the IDLE and OFF modes, we used the Scale(g) button to scroll down to a lower range option. In doing this, we found "peaking" at bin 80, which was ~0.0277g.

When the compressor was in an OFF state, we hit Start again and found that the energy at bin 80 reduced by a large amount.

From this simple experiment, we can conclude the following:

• While we expect that most applications will require a more thorough investigation of potential behaviors and performacne threats, the ADIS16228's noise, bandwidth and range appear to be sufficient for the stated goal of discerning a vibration difference betwween OFF, IDLE and ON states. 

In concluding this post, we also want to note that using double-sided tape was helpful for this quick demo, but would expect that a complete investigation would want to consider a more rigid attachment approach. The next step in this process will be to determine the appropriate spectral alarm settings for detecting these conditions.  More on that in our next post!