Kinematic analysis of a plane deployable mechanism assembled by four pyramid cells

A new four pyramid cell mechanism based on a spatial seven-linkage loop mechanism is proposed in this article which can be employed to assemble large deployable mechanisms. The mobility, kinematics and singularity characteristics of this cell mechanism are analyzed and the assembling method is provided. Based on this kind of cells, a new plane deployable mechanism is designed and its retractable ratio calculated. The results show that these cells are easy to be assembled into a large structure of deployable mechanism. The mobility of the assembled mechanism is only one, and thus its fold deployment is well controllable. When the mechanism is wholly deployed, it has good mechanic performance due to its singularity. Large deployable mechanisms can be designed by these cells and they have a good prospect in aeronautic and astronautic engineering.