Tham khảo tài liệu 'autonomous underwater vehicles part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Real-Time Optimal Guidance and Obstacle Avoidance for UMVs 89 geometry of the MURS allows the planner to construct a keep out zone corresponding to the MURS propeller and aft control surfaces. The UUV rendezvous trajectory must avoid this area. Once the rendezvous plan has been agreed upon and acknowledged both the UUV and the MURS proceed to position 3 for rendezvous stage B . Finally at position 4 the recovery operation stage C is completed. MURS Holding Pattern Fig. 19. Manifold of initial and final conditions Fig. 20. Proposed rendezvous scenario The simulated rendezvous scenario assumes three stages communication A execution B and recovery C respectively. From the trajectory generation standpoint we are primarily concerned with optimizing the path that would bring the UUV from its current position point 2 to a certain rendezvous state point 3 in the preset time Tr proposed by the MURS while obeying all possible real-life constraints and avoiding the MURS keep out zone. Figures 21 and 22 present a computer simulation in which a MURS is moving due east at 1m s with the docking station at a depth of 15m. A UUV is located 800 meters away. The MURS wishes to conduct a rendezvous operation Tr minutes later and sends the corresponding information to the UUV. This information includes the proposed final position Xf y f Zf rendezvous course speed and time. Figure 21 shows several generated trajectories which meet the desired objectives for this scenario and also avoid an obstacle located along the desired path to MURS. These trajectories differ by the arrival time Tr. During handshaking communications with the MURS the UUV determines whether the suggested Tr is feasible. Of the four trajectories shown the trajectory generated for 90 Autonomous Underwater Vehicles Tr 450s happens to be infeasible the constraints on controls are violated . The solution of the minimum-time problem for this scenario yielded 488 seconds as the soonest possible rendezvous time. The .
