Abstract: In order to reveal kinematic characteristics of spherical deployable mechanisms composed of any number of spherical scissors elements, the degree-of-freedom characteristics and method of kinematics analysis for such mechanisms are studied. Based on screw theory, degree-of-freedom characteristics of spherical scissors deployable mechanisms are analyzed, which are a spherical scissors element, its serial kinematic chain and multiple branch chains. On the basis of analysis results, the degree-of-freedom characteristics of spherical scissors deployable mechanisms which consist of spherical scissors elements are obtained. According to this, the 1-DOF mechanisms with any number of spherical scissors elements and branch chains are constructed. Based on spherical geometry, kinematics analysis of the spherical scissors deployable mechanism with two serial spherical scissors elements is given, so does the spherical scissors deployable mechanism with any number of m serial spherical scissors elements. On this basis, kinematic characteristics of spherical scissors deployable mechanisms with n branch chains are analyzed. To this kind of mechanism, the universal method of kinematics analysis is presented, and the numerical examples are given to prove the validity of the method. The software of kinematics analysis of spherical deployable mechanisms which consist of any number of spherical scissors elements is developed, which achieves automatic kinematics analysis and calculation for such mechanisms. It has the important application value and the practical significance in engineering fields.

Key words: Deployable mechanism, Kinematics analysis, Scissors mechanism, Screw theory, Spherical mechanism