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I've noticed that a lot of flight controllers have multiple IMUs and Barometers, which makes sense from a redundancy standpoint. But the interesting thing is that they use different models of IMUs. For example, the Pixhawk 6x has an ICM-20649 AND an ICM-42688-P AND an ICM-42670-P.

What is the purpose of having different IMU models on the same board? Is there some sort of signal processing advantage? If so, how does that work, and how measurable is the advantage?

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As far as I can see from the datasheets, the 20649 supports 4 - 30 g and the second one supports 2 - 16 g. So it may be just a way to have a wider range of measurement.

https://www.mouser.de/ProductDetail/TDK-InvenSense/ICM-20649?qs=u4fy%2FsgLU9OPqPg7X9Rk3A%3D%3D

https://www.mouser.de/ProductDetail/TDK-InvenSense/ICM-42605?qs=gZXFycFWdAO0MPgeewGYjQ%3D%3D

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In some cases, this may be a form of "dissimilar redundancy."

By using different models of IMU, if one has a fault or bug in the design/software the other should remain unaffected. Sometimes three sensors will be used so that the controller can also determine which sensor is faulty, on the assumption that the two that still agree are working, but two-sensor implementations are able to identify a fault and warn the operator.

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