交会对接技术是我国载人航天工程二期需要掌握的关键技术，而接近段轨道转移又是交会中一个重要环节。论文以空间交会接近段转移为背景，研究了接近段联合机动下的最优控制，分析了主要误差项对终点位置和速度精度的影响，并提出了在短时间内使C-W方程误差尽可能小的参数设计方法，这些研究可为工程中接近段转移轨迹的规划问题提供重要参考。主要研究成果如下：研究了接近段联合机动下的最优控制问题。（1）根据最优控制下有限推力的作用规律，制定了联合机动的具体策略：滑行-推进模式和滑行-推进-滑行-推进模式；针对不同的机动策略提出了相应的优化方法，对滑行-推进模式，可通过数值计算、结果比较直接得到燃料最优解；对滑行-推进-滑行-推进模式，可使用优化方法求解，为此，建立了相应的优化模型，采用了PSODE优化算法，通过数值计算得到了燃料最优解。（2）比较了双冲量机动、最优控制下小推力机动、滑行-推进模式和滑行-推进-滑行-推进模式四种机动方案下的燃料消耗等情况，小推力机动最省燃料，但轨迹视界角最大，滑行-推进-滑行-推进模式轨迹视界角最小；研究了滑行-推进-滑行-推进模式下，不同比冲比对燃料消耗的影响，结果表明比冲比越大，小推力机动燃料消耗少的优势越明显。研究了主要误差项对终点精度的影响。（1）建立了导航误差、控制误差和轨道模型误差仿真模型，并使用Monte-Carlo方法进行数值仿真，分析了误差项对终点位置和速度精度的影响，仿真结果表明Y向状态对误差项比较敏感，速度导航误差对终点平面内状态的影响比较大，小推力机动误差对终点平面内速度的影响比较大。（2）通过比较C-W、二体、J2、HPOP四种轨道模型下终点位置和速度可知，Y向状态对轨道模型比较敏感，J2项摄动对轨迹影响比较大，而且C-W模型的非线性误差、非零偏心率误差与摄动误差在接近段转移过程中会相互抵消一部分，减小了C-W模型的误差。（3）建立了修正C-W方程，引入了J2项摄动一阶项和引力二阶项；研究了在短时间内，使C-W方程误差尽可能小的参数设计方法；通过数值仿真算例，验证了参数设计方法的有效性。
In the second phase of China’s manned space program, rendezvous and docking technology is a key technology to grasp, in which orbital transfer in approach phase plays an important part. This dissertation bases on orbital maneuver in approach phase. It studies optimal control problem on joint maneuver, analyzes the main errors’ influence on the terminal position and velocity accuracy, and also presents a parameter-design measure to decrease the error of C-W equation. These studies provide important reference to orbital design and control problem in approach phase for engineering application. The main results are summarized as follows.Optimal control problem on joint maneuver in approach phase is studied. (1) According to optimal control law on finite thrust, specific maneuver strategies on joint maneuver are established, including coasting-propulsion mode and coasting-propulsion-coasting-propulsion mode. For coasting-propulsion mode, fuel optimal solution can be directly obtained by numerical computation and results comparison; for coasting-propulsion-coasting-propulsion mode, optimization method must be used, including creating optimization model and adopting PSODE optimization algorithm. (2) Comparing fuel consumption and others of four different maneuver strategies - two-impulse, low-thrust, coasting-propulsion mode and coasting-propulsion-coasting-propulsion mode, low-thrust maneuver consumes least fuel, but gets largest horizon angle; the horizon angle of coasting-propulsion-coasting-propulsion mode is the smallest. The impact of specific impulse ratio on fuel consumption is also studied. The results show the higher the ratio of specific impulse, the more obvious continuous thrust’s advantage of low fuel consumption.The main errors’ influence on the terminal position and velocity accuracy is studied. (1) The navigation error, control error and trajectory error model are established. Besides, Monte-Carlo simulation method is used to analyze the precision. Simulation results show the state in Y direction is more sensitive to errors; the impact of velocity navigation error is greater on the state in plane; the impact of continuous thrust control error is greater on the velocity in plane. (2) Comparing terminal position and velocity under four different orbital model- C-W, Two-body, J2, HPOP, the state in Y direction is more sensitive to orbital model; J2 perturbations have a bigger impact on transfer orbit; the nonlinear error, non-zero eccentricity error and perturbation error of C-W model cancel out each other a lot and the error of the model is reduced. (3) A modified C-W equation is established, introducing J2 perturbation first-order item and gravitational second-order item. A parameter-design measure is studied to decrease the error of C-W equation in a short time and the measure is proved to be effective by examples.
