Fig. 1. Schematic diagram and three-dimensional diagram of main optical terminal of networking laser communication

Fig. 2. Composition of servo subsystem

Fig. 3. Optical closed loop with velocity loop as inner loop

Fig. 4. Optical closed loop with position loop as inner loop

Fig. 5. Posture, velocity, and acceleration curves of six axis swing table. (a) Posture; (b) velocity; (c) acceleration

Fig. 6. Tracking miss distance obtained by optical closed loop. (a) Based on position loop; (b) based on speed loop

Fig. 7. Simulation block diagram of Simulink optical closed loop based on velocity loop

Fig. 8. Simulation block diagram of Simulink optical closed loop based on position loop

Fig. 9. Tracking miss distance of Simulink optical closed loop. (a) Based on speed loop; (b) based on position loop

Fig. 10. Position curves of motor starting at velocity of 0.01 (°)/s. (a) Low speed starting based on position loop; (b) stable motion based on position loop; (c) low speed starting based on velocity loop; (d) stable motion based on velocity loop

Fig. 11. Tracking error under different feedforward gains