Welcome to the Systems Integration space for how-to mount sensors! Use the following links to navigate to specific pages to learn more about specific sensors!

Blending vs. Switching

Ardupilot commonly offers 2 different sensor modes - blending or switching. Blending blends two sensor sources to create a filtered final result from the two individual inputs, while switching will switch from one sensor to the other dynamically.

For certain sensors, blending is encouraged (gps, gps+barometer, etc). However, certain sensors “blend” algorithms are old and certain sensors may provide measurement accuracy which is better than what will result from a blend of two sensors!

Common items that (currently - 2023-06) aren’t encouraged to be blended include rangefinder + altitude estimates, as well as optical flow + position estimates. This is because rangefinders and optical flow are able to give centimetre level accuracy on their own, while other sources of absolute position (gps+barometers) are only able to give metre-level accuracy. Blending the two sensors worsens the accuracy of the final result and may lead to worse behaviour than switching between sources.

Note that IMU’s and AHRS systems are also switched - there is no blending between IMU’s, ardupilot will dynamically choose a “primary” AHRS+IMU system (AHRS is tied to IMU instance), and use that one. The AHRS system will remain primary until performance degrades and another system must be used.