AHRS sensor (IMU) for outdoor antenna

[-=Hulk=-]

Hello

I have a high directional 4G outdoor dish antenna, and I wanted to fix it on a Diseqc motor to make it rotate horizontally (~150°) and perhaps also add a small linear actuator to optimize the vertical inclination (+/-20°).

But I wanted also to add an IMU in order to get information about the orientation of the antenna.
A +/-2° accuracy is good enough.
Actually, I only need the geographical orientation (like a compass) and possibly the vertical inclination.

Now I have following questions:

1. Do I need a full AHRS sensor (= accelerometer + gyroscope + magnetometer + fusion algorithm) or a magnetometer is enough? Does the accelerometer/gyroscope/magnetometer data adds accuracy to the calculated geographical heading of the fusion algorithm?

2. Since the antenna will only be able to move (slowly) 150°H and 20°V I won’t be able to calibrate the sensors after every power-up of the device. Is that an issue with such device? Is a one-time calibration (before final mounting) good enough?

3. Is this Chinese AHRS (based on a RM3100 magnetometer, which has 3 external coil antennas) module overkill? Or is a BNO055 good enough for my purposes?


Chinese AHRS (HWT901B-RS485):
https://www.aliexpress.com/item/1005002977359131.html

Inside:

The mag sensor inside:

Alternative, the Bosch BNO055 with integrated fusion algorithm:

Thank you for your help

 

[rjenkinsgb]

If it's a fixed unit, I'd have though you would get far better precision just by using good potentiometers for feedback?

If it is mobile, then you would need 3D angular feedback with such as a good accelerometer, plus a digital compass, as the base being off level would offset the inclination.