1. GPS Attitude Determination Under Antenna Array Geometry Deformation Alexander Kozlov, Alexey Nikulin, Andrei Golovan, Ali Cepe, Vladimir Chemodanov RAST 2015 Moscow State University, Russia Navigation and Control lab.

2. Attitude determination using GPS

3. Attitude determination accuracy

4. Antenna array deformations  undeformed state, no rotation  observable deformation  ambiguous deformation

5. Antenna array deformation types  Single baseline/multiple baselines are deformed  Constant/varying deformations  Stochastic/determined deformation model  Coordinated/arbitrary deformations (multiple baselines)

6. Math behind the scene  Baseline deformations  S defines which directions are allowed for deformations  If no inertial measurement unit (IMU) is present, the quantitive effect of deformation on attitude determination is fully defined by S and antenna array geometry  If IMU measurements are available, the effect depends on S, and antenna array geometry, and gyro measurement quality and satellite motion

7. No IMU, 2 antennas

8. No IMU, 3 antennas

9. No IMU, 4+ antennas

10. GPS/IMU data fusion, 2 antennas

11. GPS/IMU data fusion, 3 antennas

12. GPS/IMU data fusion, 4 antennas

13. Summary  Antenna array geometry deformations can be observable or ambiguous in terms of attitude determination  If observable, without IMU geometry of antenna array and geometry of deformation both define the accuracy of attitude determination  IMU measurements allow some antenna array geometry deformations to become observable  With IMU, satellite motion is also significant