Hi @KaiBo, Have you checked these instructions? Instructions Navigator Lib
I presume that you are trying to interface the sensors on Raspberry Pi without using the BlueOS image, is that right?
If this is the case, in order to access i2c/spi/uart on Raspbian, you need to set the overlays (this is done automatically in BlueOS).
If they are set, you will be able to check i2c devices available: please follow this to check.