Original Article

A novel 4-RRCR parallel mechanism based on screw theory and its kinematics analysis Sheng Guo, Congzhe Wang, Haibo Qu and Yuefa Fang In this article, a novel 4-RRCR parallel mechanism is introduced based on screw theory, and its kinematics and singularity are studied systematically. First, the degree of freedom analysis is performed using the screw theory. The formulas for solving the inverse and direct kinematics are derived. Second, a recursive elimination method is proposed to solve the Jacobian matrix based on the algebra operation of reciprocal product. Then, three kinds of singularity, i.e. limb, platform, and actuation singularities are analyzed. Finally, the analysis proves that the proposed mechanism possesses two advan-tages of simple forward kinematics and no platform singularity