Hybrid Positioning and Sensor Integration - Global Navigation Satellite Systems: Signal,Theory and Applications - page 348

GPS/IMU. On the one hand, with an ordinary GPS/IMU, the trajectory becomes notched
because the position is revised forcibly by GPS due to drift error. The platform changes its
attitude rapidly, especially in the corner, so the notched trajectory is very obvious. The drift
error remains in the calculation until the alignment of IMU is complete. On the other hand,
with GPS/IMU/images, the drift error of IMU is aligned by initialization from the bundle
block adjustment. Moreover, the trajectory is very smooth in the corner.

Hybrid position and attitude
200 Hz

IMU
Ve l o c i t y

GPS
Ve l o c i t y

+ ‐
+ ‐

IMU
200Hz

GPS

1Hz

IMU
Position

GPS
Position

Ve l o c i t y E r r o r Position Error

Camera

Kalman
filter
1Hz

Image orientation
(BBA)

Position

0.1Hz

Attitude

Fig. 6. Strapdown navigation diagram with images

GPS/IMU/images GPS/IMU

25670

25665

25660
25655

25650

25645
25640

25635

25630

11220 11210 11200 11190 11180 11170 11160 11150 11140 11130

X （ m ） JGD2000

Fig. 7. Hybrid position

4.4 Evaluation of hybrid positioning
Trajectory tracking by ordinary GPS/IMU integration is compared to the combining of
GPS/IMU and continual digital images, in order to validate this combination. Figure 8 shows