LIS3DH drift over time

[Arek Arkowski]

Hello

I was asked to build a device which will determine if a box is in either of the three following states: perpendicular to ground, tilted forwards (10° or more), tilted backwards (10° or more). I am attaching a simple drawing for visualization of the three states.

I was ordered to build 10000 of such devices that's why I want to make sure everything will work.

My biggest concern is the drift. For example, based on the accelerometr values I calculate that the box is tilted forwards, let's say 15°. Will this value change over time? Will it drift towards 0° or stay at 15° for years?

I'll be grateful for any help.

[Eleon BORLINI]

Hi @Arek Arkowski​ , please note there are concurrent possible drift in the long time: time offset drift, temperature offset drift (ds value), post solder drift... Taking into account only the time offset drfit, the capability of maintaining a specific tilt value depends also on the accuracy you want to achieve (es. a drift from 14° to 15° is acceptable)? What I would suggest you is to use a threshold (INT1_THS (32h), LSB equals to 16mg) to detect a tilt change and generate an interrupt in case the tilt becomes bigger or lower than the set value. When yuo detect the tilt and you are sure is not due to a movement of your system, you can reset the LIS3DH offset and go on with the monitoring. Regards

[Eleon BORLINI]

I can confirm you from the accelerated life tests performed by our quality that the maximum drift along the "worst" axis (among x, y or z, it depends from the package stress) is below 1 degree in terms of years. Especially the z-axis is stable, so I suggest you to place the board sensing the gravity along z-axis. And especially the drift occurs in case of high environmental humidity, so you can guarantee a proper accuracy in case the environment conditions are stable. Regards

[Arek Arkowski]

Hi Eleon

Thank you for your answer. My plan is to measure the z-axis only so it is good to know it helps a little. Anyway I am much calmer now.