Abstract: Among the branches of the traditional three degrees of freedom (3-DOFs) rotational parallel mechanism, there are multi revolute joint axes intersecting at one common point. This strict geometric requirement brings much difficulty to the manufacturing, which will increase the manufacturing cost and make it hard to ensure the machining accuracy. So, the applications of this kind of parallel mechanisms are severely restricted. To solve the above-mentioned problem, a new kind of 3-DOF rotational parallel mechanism without intersecting axes is proposed. The moving platform of this kind of parallel mechanism has three rotational freedoms and can realize any given three dimension rotations. Because there are no intersecting axes among the branches, this new kind of rotational parallel mechanism has the advantages of easy manufacturing and the accuracy can be easily ensured. The kinematic solutions and orientation workspaces of two cubic parallel mechanism of this kind are studied which shows that this kind of parallel mechanism can realize the expected 3-DOF rotations and has large rotation workspace. This new kind of rotational parallel mechanism can be used as attitude control device.

Key words: 3-DOF;cubic parallel mechanism;rotational workspace;attitude contro