Sensitivity of an accelerometer defines at what rate the sensor converts mechanical energy into an electric signal (the output) and this will define the acceleration measurement range of the accelerometer. They are also the result sometimes of low-pass filtering used to prevent aliasing. The frequency response of a sensor is typically governed at the high frequency end primarily by the mechanical resonance of the sensor. They can however be used to determine velocity or displacement amplitude of higher frequency (above 5 hertz) periodic motion, or simple harmonic motion (check out Mide's simple harmonic motion calculator for more information - Note: enDAQ is a division of Mide). Accelerometers that do not have a DC response will have an intrinsic decay function that will result in significant error during numeric integration, especially over long duration events. DC-response accelerometers are also required for applications where velocity (by integrating the acceleration data), or displacement (double integrated) is of interest. If the lower range of the bandwidth doesn't go to 0 Hz (called DC-response) the accelerometer won't be able to measure static accelerations like gravity or slow vibrations (< 2 Hz) like those seen in marine environments. ![]() The enDAQ sensor's (formerly Slam Stick) frequency response is shown below as an example (taken from the datasheet) it conveniently compares decibel to percentage deviation also.īandwidth information tells the user if the accelerometer can measure slow or static accelerations and also defines the upper frequency limit where the accelerometer will still be accurate. Most data sheets will have a typical frequency response curve to assist the user. The tolerance band can be specified in percentage and/or dBs with typical bands being ±5%, ☑0%, ☑ dB, and even ☓ dB. The bandwidth is usually specified as a tolerance band, relative to the reference frequency sensitivity (usually 100 Hz). The frequency response specification shows the maximum deviation of sensitivity over a frequency range. You won't get accurate results if the bandwidth of the accelerometer doesn't include the frequency of the motion, vibration, or shock you are hoping to measure. Frequency Response or Bandwidthīandwidth, or frequency response, is the most important parameter in accelerometer selection. Check out my blog post on accelerometer selection for a more in depth discussion and breakdown between the different types. ![]() Generally a capacitive MEMS accelerometer is best for motion sensing applications (think human motion which is relatively slow/low frequency) piezoelectric is best for vibration and piezoresistive is best for shock testing. ![]() The accelerometer's datasheet will, or should, tell you exactly what type it is because picking the right accelerometer type for your application can make all the difference. There are three main types of accelerometers: capacitive MEMS, piezoelectric, and piezoresistive. Accelerometer Type - Capacitive MEMS, Piezoelectric, or Piezoresisitve In this post I will provide brief descriptions of 10 specifications often listed on accelerometer datasheets that you can use as a reference for whenever you are shopping around for accelerometers - the sensor that tells us how the world moves! I've also included a one page cheat sheet for quick reference - the link is at the bottom of the page.Īccelerometer Specifications 1. And this makes shopping for an accelerometer an even more difficult task than it already is! I frequently talk with customers who don't fully understand the different specifications used on an accelerometer's datasheet. Accelerometer companies, understandably, try to position their products in the best light possible, and they often do so by using complicated terminology and units for the accelerometer's specifications. Why, why, why are accelerometer datasheets so confusing? There's a reason.
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