Fig. 1. Block diagram of vision position system of drones

Fig. 2. Transform relationship of the frame between vehicle and vision positioning system in the ground test

Fig. 3. Setup of sign point in the vehicle

Fig. 4. Accumulated schematic diagram of vehicle positioning error

Fig. 5. Graph optimal model of vehicle pose estimation with a circle trajectory motion

Fig. 6. Error statistical of linear posture estimation algorithm

Fig. 7. Error statistical of nonlinear optimal posture estimation algorithm

Fig. 8. Mean error distribution of relative 3D localization error of estimation algorithm before and after nonlinear optimization

Fig. 9. Actual posture estimation accuracy verification experimental device

Fig. 10. Result of pose estimate based on linear algorithm

Fig. 11. Result of pose estimate based on nonlinear algorithm