Abstract: Aiming at the strong kinematic coupling problem of parallel mechanism, a novel uncoupled rotational parallel mechanism with two degrees of freedom was proposed. Its kinematical output characteristics were analyzed and mobility was calculated in terms of the position and orientation characteristics method. According to the actuated wrench screw theory and the closed vector approach, mathematical models of the posture and the angular velocity of the mechanism were established. Singularity analysis was performed based on the linear dependence of the kinematic screw system and constraint screw, respectively, and all singular configurations were given as well. The expression mapping the kinematical conditioning index and the structural factor, the input angular displacement was deduced. Structural condition of the fully-isotropic performance for the mechanism was discussed in detail. Finally, kinematical simulation of the mechanism was carried out. The results indicate that the mechanism has the uncoupled kinematics characteristics. Especially, when the structure size of the mechanism meets certain requirement, the velocity Jacobian is an identical matrix, therefore, the mechanism will show the fully isotropic performance.
Key words: parallel mechanism; kinematics analysis; singularity; screw theory; uncoupled