Simple Measures

The 3-axis accelerometer works with a 9 V supply and provides 3 outputs, one per axis, with 333 mV per g.

Installation

Three analog inputs are required.

First Measures in mV

First project consists just on reading and monitoring the values read by the accelerometer. 

On the example provided, results are 
  • X-axis = 1707 mV
  • Y-axis = 1677 mV
  • Z-axis = 2263 mV
Picture

Second Measures in g

Now, let's convert the mV into g. 1 g ≈ 9,80665 m.s-2

For each axis, calculation consists on:
  • read value,
  • convert from integer to real,
  • rest a base value, corresponding to the origin 0 g (or optionally to the Normal Earth attraction 1 g to skip it) 
  • divide by the gain, 333 mV / g
  • use the Text instruction for formatting
  • display

The base values here are: 
  • 1660 mV for X- and Y-axis, 
  • 2330 mV for Z-axis.
Picture

First Discoveries

This test is highly recommended to identify the X-, Y- and Z-axis.

Then, the Earth attraction could be measured by rotating the sensor by 90°.

Another test is to move the sensor at constant pace on a table and watch what happens.

First conclusion is an accelerometer measures acceleration, that is, a change of speed.

Earth attraction is just one acceleration.

Next

Self-Positioning Horizontal Device