For the large-angle attitude maneuver of spacecraft under complex constraints, a efficient maneuver path planning for attitude and time scaling method on 3-dimensional special orthogonal group was proposed. Aiming at handling the attitude constraints during maneuvering, a gradient-based obstacle avoidance methodology was designed and the attitude routes and desired angular velocity trajectory was obtained on the virtual time domain. Considering the maximum output torque of the actuator, an iterative nonlinear time scaling method was proposed to adjust the angular velocity/control torque. Simulation results show that the proposed method not only satisfies the attitude constraints and the control torque constraints during the spacecraft maneuver process, but also significantly shortens the maneuver time comparing with existing methods. Novel results provide a new insight for efficient constrained attitude planning and controller design.

As the constellation scale expands, the traditional constellation management mode imposes a substantial burden on ground stations. In order to construct a high-efficiency management mode for the low earth orbit (LEO) mega-constellation and to respond to the mission rapidly, a management strategy using distributed management domains as well as their dynamic evolution and maintenance methodology is proposed. In this paper, the distributed management domain is described as a variable topology consisting of groups of categorized satellites. The mega-constellation management topology is divided into a limited number of sub-topologies, determined by minimizing the average transmission latency and the frequency of management updates. Considering the dynamic of constellation, a method for predicting satellite management switching time is proposed, and a fast management maintenance strategy is designed to reassign satellites into new sub-topologies, ensuring a low overall update frequency of the management domain structure. Simulation validates that the management strategy divides the mega-constellation into dozens of management sub-topologies with similar structure and low-frequency management updates. Throughout the management period, each satellite remains under management with low transmission latency, and the overall management topology maintains long-term stability.

The increasing complexity of on-orbit tasks imposes great demands on the flexible operation of space robotic arms, prompting the development of space robots from single-arm manipulation to multi-arm collaboration. In this paper, a combined approach of Learning from Demonstration (LfD) and Reinforcement Learning (RL) is proposed for space multi-arm collaborative skill learning. The combination effectively resolves the trade-off between learning efficiency and feasible solution in LfD, as well as the time-consuming pursuit of the optimal solution in RL. With the prior knowledge of LfD, space robotic arms can achieve efficient guided learning in high-dimensional state-action space. Specifically, an LfD approach with Probabilistic Movement Primitives (ProMP) is firstly utilized to encode and reproduce the demonstration actions, generating a distribution as the initialization of policy. Then in the RL stage, a Relative Entropy Policy Search (REPS) algorithm modified in continuous state-action space is employed for further policy improvement. More importantly, the learned behaviors can maintain and reflect the characteristics of demonstrations. In addition, a series of supplementary policy search mechanisms are designed to accelerate the exploration process. The effectiveness of the proposed method has been verified both theoretically and experimentally. Moreover, comparisons with state-of-the-art methods have confirmed the outperformance of the approach.

The safety of a space station under normal and abnormal conditions can be ensured only by comprehensively identifying various hazards of the space station during its whole mission cycle and formulating control measures against each hazard. This paper describes the safety design process of the China Space Station, as well as detailed safety design measures for general hazards, fault hazards, dangerous events, and critical missions, so as to achieve safety goals as far as possible under the circumstances of limited resources and transportation capacity of the space station. The key work of safety design includes identification of hazard sources and dangerous events, formulation of safety control measures, and design of safety safeguard measures. Identification of hazards and hazardous events is based on both defined content in design schemes and previous on-orbit flight experience of manned spacecraft. The formulated safety control measures are based on analyzing each hazard to determine key links of safety control and formulate corresponding control measures for effective hazard control under minimum resource cost. In the case of a serious failure, the space station can remain safe within a certain time by its autonomous hazard disposal.

This study investigates the optimization configuration problem of control moment gyroscopes for flexible vibration suppression of large space structures. First, the structural dynamic model of an unconstrained plate-like flexible spacecraft with control moment gyroscopes is established using the Lagrangian method and the finite element method. Second, an optimization problem is established with the positions of control moment gyroscope array as variables and the linear quadratic index of mechanical energy during vibration process as the objective function. Additionally, an improved gray wolf optimizer is used to solve the optimization problem. The optimization results show that the control moment gyroscopes should be primarily placed on the corners of the spacecraft in a symmetrical manner. Finally, the priority of control moment gyroscope installation positions was studied using topological iteration. The results indicate that the control moment gyroscopes should be primarily installed on the corners, followed by the central positions, and then gradually expanded outward.

The contact point configuration should be carefully chosen to ensure a stable capture, especially for the non-cooperative target capture mission using multi-armed spacecraft. In this work scenario, the contact points on the base and on the arms are distributed on the opposite side of the target. Otherwise, large forces will be needed. To cope with this problem, an uneven-oriented distribution union criterion is proposed. The union criterion contains a virtual symmetrical criterion and a geometry criterion. The virtual symmetrical contact point criterion is derived from the proof of the force closure principle using computational geometry to ensure a stable grasp, and the geometry criterion is calculated by the volume of the minimum polyhedron formed by the contact points to get a wide-range distribution. To further accelerate the optimization rate and enhance the global search ability, a line array modeling method and a continuous-discrete global search algorithm are proposed. The line array modeling method reduces the workload of calculating the descent direction and the gradient available, while the continuous-discrete global search algorithm reducing the optimization dimension. Then a highly efficient grasping is achieved and the corresponding contact point is calculated. Finally, an exhaustive verification is conducted to numerically analyze the disturbance resistance ability, and simulation results demonstrate the effectiveness of the proposed algorithms.