Space truss construction modeling based on on-orbit assembly motion feature

More space truss construction has been planned to develop and utilize space resources.These trusses are designed in the way of large-scale,complex,modular,and on-orbit assembly.To meet the upcoming challenge of large-scale space infrastructure construction,it is necessary to study space truss automation design and robotic construction.This paper proposes an ordinal finite screw adjacency matrix model(OFSAMM),focusing on the relationship between assembly motions,to express and compute a space truss structure.In this model,a space truss is abstracted as a set of ordered assembly motions,each of which is recorded as a finite screw as the basic element of the truss and its assembly.The operation of truss transformation is also derived under this model.Therefore,the truss configuration,the assembly sequence,the truss sub-assembly,the truss components,and the on-orbit assembly task can be expressed and calculated in a unified model,which is calculated and stores the truss topology and assembly with the minimum storage cost.At the end of this paper,we introduce how to synthesize and optimize space truss design through two cases.The study will help to improve design efficiency.Furthermore,it provides a theoretical basis for the automatic construction of space truss structures,especially in the next stage.

Conceptual design and analysis of legged landers with orientation capability

The lander with orientation capability is of fundamental importance for the“Returning”mission because its body can be the base with a suitable launching angle for the ascender lifting off.This paper proposes the conceptual design and verification of Landers with Orientation Capability(LOCs).Firstly,the topological composition of the lander is analyzed and expressed in the form of Lie group,which provides the fundamental principle for the type synthesis of LOCs.Then,the type synthesis approach for designing LOCs is proposed,which includes designing the Equivalent Parallel Mechanism(EPM)and the auxiliary limbs.Numerous mechanisms of LOCs with twodimensional rotational motions are obtained based on the type synthesis approach by developing and combining the EPMs and auxiliary limbs.Afterward,kinematics and Jacobian matrix of a typical legged lander are developed,the workspace is analyzed,singularity configurations are analyzed based on the wrench graph method,and finally,the orientation capability is analyzed.The pitch and yaw angle reach 17.5°,considering the permissible range of joints.The proposed types of LOCs offer potential candidate for the“Returning”mission of the exploration mission.