Error Analysis of a Deployable Scissor-Like Mechanism with Joint Clearances

The positioning and orienting errors of a deployable mechanism used for supporting antennas directly affects the performance of the satellite. This paper focuses on the error analysis of a deployable scissor-like mechanism considering joint clearances. Firstly, kinematics of the deployable mechanism without clearances is analyzed. Then, the joint clearance is equivalent to an RPR serial chain. Motion mode analysis of adjacent units with different number of clearances are developed. Possible motion modes of the deployable mechanism regarding clearances are obtained. On this basis, error models of adjacent units and the deployable mechanism are established, which reveals the relationship between the positioning and orienting errors and clearances. Influences of joint clearances on errors are conducted. The variations of errors with respect to clearances are investigated. The maximal positioning and orienting errors corresponding to the deployable scissor-like mechanism with different distributions of joint clearances are calculated. The proposed error analysis method could also be utilized to other deployable mechanisms.