دانلود رایگان مقاله بهینه سازی یک ماموریت طولانی مدت مداری

ABSTRACT

The phasing segment of the rendezvous mission between a cargo spacecraft and a space station usually lasts for several weeks, and actually presents an orbital long-duration problem. In this study, this orbital long-duration problem is formulated as a mixed integer nonlinear programming (MINLP) problem in which the maneuver revolution numbers (integers), maneuver arguments of latitude and impulse magnitude are used as design variables at the same time. A hybrid approach is then proposed to solve this MINLP problem. First, a linear dynamics model considering the J2 term of the Earth non-spherical gravity is employed to formulate an approximate phasing problem, which is optimized using a genetic algorithm. Second, a shooting iteration process considering the coupling effect between the in-plane and out-of-plane maneuvers is proposed to improve the approximate solution to satisfy the terminal conditions of the high-precision problem. The proposed approach is demonstrated for a typical two-week rendezvous phasing mission. The results show that the proposed approach can stably obtain the near optimal high-precision solution by integrating the perturbed trajectory only a few times. Furthermore, a long-duration rendezvous phasing plan is compatible with any initial phase angles that the in-plane velocity increment remains almost unchanged when the initial phase angle changes. However, under the same conditions, the out-of-plane velocity increment has considerable variations. Compared with a two-day rendezvous phasing plan, a two-week plan could have several successive coplanar launch opportunities for the chaser by aiming different terminal revolution numbers.

5. Conclusion

This paper has presented a hybrid optimization approach for long-duration rendezvous phasing missions and then has demonstrated it for a typical two-week rendezvous phasing mission. The results show that the proposed approach can stably obtain the near optimal high-precision solution by integrating the perturbed trajectory only a few times.A long-duration rendezvous phasing plan is compatible with any initial phase angles that the in-plane velocity increment remains almost unchanged when the initial phase angle changes. However, under the same conditions, the out-of-plane velocity increment has considerable variations, which is caused by the coupling effect between in-plane and out-of-plane maneuvers. For a typical two-day rendezvous phasing plan, or plans with shorter mission duration, the total velocity increment has only one local minimum when the initial right ascension of ascending node (RAAN) of the chaser changes, and that local minimum corresponds to a quasi-coplanar launch opportunity of the chaser. However, for a long-duration rendezvous phasing plan, such as the plan with two-week mission duration, the total velocity increment has multiple local minimums as the initial RAAN of the chaser changes, and different local minimums correspond to different terminal revolution numbers. By aiming different terminal revolution numbers, a two-week plan could have more successive quasi-coplanar launch opportunities for the chaser (cargo spacecraft) than a two-day rendezvous phasing plan.