What is a 3-axis accelerometer (tri-axis)

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What this article covers:
  1. What is an accelerometer? 3-axis accelerometer
  2. construction and design
  3. How does an accelerometer works?
  4. applications
  5. datasheets

1. What is a tri-axis accelerometer?


An accelerometer, as the name suggests, is used to measure the acceleration. A 3-axis accelerometer, also known in the industry as a tri-axis accelerometer, measures acceleration along all 3 axes,namely x, y and z axes.

It is essentially a micro-electromechanical system (MEMs).

2. Construction of a typical accelerometer package:




A simpler diagram of the same:

This diagram shows a single axis accelerometer for lucidity. A tri-axis accelerometer will be more complicated in construction.

3. Working principle:


It must be evident from the diagram that it is based on the spring-mass damper system and usually uses a quartz crystal for the measurement of changes in the form of electric potential by piezoelectric effect.



  • Let us take an example of a tri-axis module, which carries MMA7361 chipset. This is operable in 2 modes of sensitivity, 
 -1.5g to 1.5g &  -6g to 6g
  • Whereas LIS331 module by STMicroelectronics can measure up to +/- 24g
  • ADXL335 is a small sensor, with ±3 g Accelerometer, designed for mobile devices.

  • ADXL001 can measure up to +/- 500g

4. Applications:


3-axis accelerometers find application in wide variety of places such as aviation and missile guidance system, vibration measurement devices and even in smartphones.

Lenovo Thinkpad has a protection system, called as 'air-bag' , based on 3-axis accelerometer sensor.(No actual airbags are involved, it's just that the hard-disk rotation is stopped, when the laptop senses a free-fall , i.e 1g force or even in the event of violent vibration)

5. Datasheets:

http://www.sparkfun.com/datasheets/Components/General/MMA7361L.pdf

http://www.analog.com/static/imported-files/data_sheets/ADXL001.pdf

http://www.analog.com/static/imported-files/data_sheets/ADXL335.pdf

http://www.st.com/internet/com/.../DATASHEET/CD00213470.pdf

Arindra Mishra

A blogger, a photographer and an Engineer. I write about technology, engineering and photogrpahy.

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