Effect of GPS Antenna mounted to Non-Rigid Body?

Hi folks! I’ve got a strange ask here.

I’m working with a drone (freefly Alta X w/ RTK GPS) and a large custom payload mounted to the vibration isolation system. The payload extends several feet above the drone and due to a combination of mechanical occlusion and EMI, GPS performance has been reduced significantly. Locks sometimes take upwards of 10 minutes.

I’ve confirmed on the ground that moving the GPS antenna to the top of the custom payload greatly improves lock speed and uncertainty, however this has some interesting ramifications:

  • the payload connects to the drone through the vibration isolation system
  • at full extents of motion, the antenna could move 3-5 inches side to side relative to the flight controller’s IMU
  • the drone is always flown in position-mode

Does anyone have any insight into how this GPS antenna mounting could effect behavior in p-mode? I’m worried that gps vs IMU “disagreement” fed into the EKF2 could lead to strange and possibly unsafe behavior.

Adam Weld