Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to moni...Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP （circular restricted three-body problem） in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.展开更多
Control moment gyroscopes(CMGs)are a favorable choice for spacecraft attitude control systems thanks to their torque amplification capability.However,their performance is hindered by geometric singularities,which can ...Control moment gyroscopes(CMGs)are a favorable choice for spacecraft attitude control systems thanks to their torque amplification capability.However,their performance is hindered by geometric singularities,which can severely limit control capabilities during attitude maneuvers.This paper proposes a hybrid attitude control system incorporating a single reaction wheel into the standard minimum redundant four-CMG pyramid configuration,providing an additional degree-of-freedom to avoid and escape singularities effectively.A comprehensive mathematical analysis of the system's Jacobian matrix,using row echelon form,is performed alongside a geometrical analysis of the hybrid configuration's momentum envelope.These analyses demonstrate the reflection of a reaction wheel inclusion into the system of four CMGs in the improvement of the system's capacity to avoid/escape singularity.Additionally,an asymptotic control law and an adapted steering law are developed to optimize control performance.The effectiveness of the proposed hybrid system is validated through simulation,which includes a comparative analysis with traditional CMG-only system.The results highlight the superiority of the hybrid system in handling singularities.展开更多
文摘Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP （circular restricted three-body problem） in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.
文摘Control moment gyroscopes(CMGs)are a favorable choice for spacecraft attitude control systems thanks to their torque amplification capability.However,their performance is hindered by geometric singularities,which can severely limit control capabilities during attitude maneuvers.This paper proposes a hybrid attitude control system incorporating a single reaction wheel into the standard minimum redundant four-CMG pyramid configuration,providing an additional degree-of-freedom to avoid and escape singularities effectively.A comprehensive mathematical analysis of the system's Jacobian matrix,using row echelon form,is performed alongside a geometrical analysis of the hybrid configuration's momentum envelope.These analyses demonstrate the reflection of a reaction wheel inclusion into the system of four CMGs in the improvement of the system's capacity to avoid/escape singularity.Additionally,an asymptotic control law and an adapted steering law are developed to optimize control performance.The effectiveness of the proposed hybrid system is validated through simulation,which includes a comparative analysis with traditional CMG-only system.The results highlight the superiority of the hybrid system in handling singularities.
