I saw a question posted by @Rocketmagnet (Why do I need a Kalman filter?) about the need for a Kalman filter. In that question, he says he's designing an UAV and lists the following sensors he will incorporate into the design:
downward facing ultrasound.
This list made me question my understanding about a few of these sensors:
My questions as a newbie are : 1) do you need a magnetometer if you have a GPS sensor? 2) Do you need a horizon sensor if you have an accelerometer and a gyroscope
Are some of these sensors listed redundant for the purposes of tracking a UAV's position/orientation/navigation?