Help in design for a recoil recording device

I am currently testing different ways to record the difference in recoil of rifles with and without muzzle breaks. I've tried spring resistance on a sled on rails. And a weighted sled without the spring. Both leave me with too much variation shot to shot. I've located this ADXL377BCPZ-RL7  accelerometer that seems to be able to measure these kinds of forces. I have also looked for schematics on how to construct a simple recording circuit to no avail. It need not be really elaborate or expensive as I have very shallow pockets. I have a hand held o-scope that I believe can record the output but no expertize in design.

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    •  Analog Employees 
    on Nov 18, 2014 9:17 PM

    For any future reviewers, this was unfortunate. While I didn't appreciate the communication approach, I do hate it when we miss a chance to help someone, especially when they are making a genuine attempt to learn something new.  Most of the contributors to this forum have full time commitments outside of supporting these requests, so we are not always able to respond as quickly as we would like. Anyway, we do want to help so let me offer some thoughts on this.

    The ADXL377 provides three analog output signals, which represent the acceleration that it experiences with respect to time. In this particular application, the recoil of the gun comes from an event that releases a lot of energy in a very short time period, so the peak acceleration values could be high.  The short duration of this burst would be what some would call an impulse. This is an important piece of information, because it will drive selection of the sensor and the data acquisition system that captures its signals for observation.  There are two key attributes that will warrant early consideration: dynamic range and bandwidth:

    The impact of both dynamic range and bandwidth can be seen in this figure (ADIS16204 datasheet)

    In the following figure (ADIS16204 datasheet), the impact of the 400Hz filter is obvious: peak information is not available from the slower response. 

    REFERENCE:

    http://www.analog.com/static/imported-files/data_sheets/ADIS16204.pdf

    Having offered this, the ADXL377's 200g range and 1300 Hz of bandwidth are better suited for gun recoil, in comparison. However, I am not sure that it will suffice for capturing the peak acceleration.  The following reference asserts that a 25-50kHz sensor is needed (see page 11)

    http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1206&context=mesp

    While we could debate the impact of their mechanical fixture and other influences,  the dependence on higher bandwidth for peak resolution is noteworthy by itself. This reference also offers some nice ideas on data acquisition systems as well.

    In addition, the following web site has a nice tutorial on data acquisition systems as well.

    What Is Data Acquisition? - National Instruments

    The bottom line is that this is a pretty vast topic, which may require a little more definition in requirements but I hope that this helps start the discussion.  I am happy to continue the discussion, but please note that we are all very busy and tend to work on things that are well defined first, then move to things that need help in the definition process.  That is just based in a common desire to help as many people as we can, not an indictment of anyone's ability or of their perceived value.  We appreciate your business and hope that we can help you get where you need to go, even if you determine that you need to user a higher bandwidth sensor approach. 

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  • 0
    •  Analog Employees 
    on Nov 18, 2014 9:17 PM

    For any future reviewers, this was unfortunate. While I didn't appreciate the communication approach, I do hate it when we miss a chance to help someone, especially when they are making a genuine attempt to learn something new.  Most of the contributors to this forum have full time commitments outside of supporting these requests, so we are not always able to respond as quickly as we would like. Anyway, we do want to help so let me offer some thoughts on this.

    The ADXL377 provides three analog output signals, which represent the acceleration that it experiences with respect to time. In this particular application, the recoil of the gun comes from an event that releases a lot of energy in a very short time period, so the peak acceleration values could be high.  The short duration of this burst would be what some would call an impulse. This is an important piece of information, because it will drive selection of the sensor and the data acquisition system that captures its signals for observation.  There are two key attributes that will warrant early consideration: dynamic range and bandwidth:

    The impact of both dynamic range and bandwidth can be seen in this figure (ADIS16204 datasheet)

    In the following figure (ADIS16204 datasheet), the impact of the 400Hz filter is obvious: peak information is not available from the slower response. 

    REFERENCE:

    http://www.analog.com/static/imported-files/data_sheets/ADIS16204.pdf

    Having offered this, the ADXL377's 200g range and 1300 Hz of bandwidth are better suited for gun recoil, in comparison. However, I am not sure that it will suffice for capturing the peak acceleration.  The following reference asserts that a 25-50kHz sensor is needed (see page 11)

    http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1206&context=mesp

    While we could debate the impact of their mechanical fixture and other influences,  the dependence on higher bandwidth for peak resolution is noteworthy by itself. This reference also offers some nice ideas on data acquisition systems as well.

    In addition, the following web site has a nice tutorial on data acquisition systems as well.

    What Is Data Acquisition? - National Instruments

    The bottom line is that this is a pretty vast topic, which may require a little more definition in requirements but I hope that this helps start the discussion.  I am happy to continue the discussion, but please note that we are all very busy and tend to work on things that are well defined first, then move to things that need help in the definition process.  That is just based in a common desire to help as many people as we can, not an indictment of anyone's ability or of their perceived value.  We appreciate your business and hope that we can help you get where you need to go, even if you determine that you need to user a higher bandwidth sensor approach. 

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