Accelerometer calibration

Reading through the wiki pages I’v been unable to get a firm grasp of how accelerometer calibrations work. I have all our trackers set to calibrate continuously and with gravity filter applied. We display all accelerometer data visually and can see that several vehicles display high values on some axis, even while vehicle is stationary and switched off. We use FMB920’s, FMC125’s, FMC920’s.

Doesn’t auto calibration mean that these lines would all hover around zero whenever the vehicle is stationary? See attached example, when the lines are more or less flat is when vehicle was not moving. These exaggerated values end up raising false alarms, as can be seen from all the triangles in the chart.

Is it possible to force an actual calibration remotely to get these lines to zero correctly?

Hi Heinburgh,

Good day, The values of the x, y, and z axis on an accelerometer when it’s idle aren’t always precisely the same and can vary depending on several factors

  • Gravity: In most cases, one axis will read close to 1g (+/- 9.81 m/s²) due to the Earth’s constant gravitational pull. This axis typically aligns with the direction of gravity, usually pointing downwards.

  • Sensor orientation: The specific axis that reads close to 1g depends on how the accelerometer is positioned. For example, if it’s lying flat on a table, the z-axis might read near 1g, while the x and y axes read close to 0g.

  • Sensor noise: Even when idle, accelerometers experience internal noise from electronics and other factors. This noise can cause small fluctuations around the expected values.

Therefore, you can’t expect a single, universal set of values like 0 when idle for an idle accelerometer

For the Auto Calibration, if you are using firmware above 03.28.07.Rev.02 There is a new New Auto Calibration Algorithm that is available through our HD. If you need more information about this, you can create an HD ticket or contact your sales manager, If you don’t have any contacts with our Sales managers, please contact them on our official website and click on the “Contact Us” button. When you click, please fill out the form and submit it. Note: as a topic, please choose “Vehicle telematics”. Or you can send an e-mail with a description of your situation to

Best Regards
Maynard C,

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