Abstract: Kinematic analysis of forging manipulator is the basis for motion control of the forging manipulator. As most scolars only analyzed kinematics of the main-motion mechanism of the typical DANGO & DIENENTHAL(DDS) forging manipulators, kinematic analysis of the whole mechanism of a typical DDS forging manipulator is carried out. The whole mechanism is a hybrid serial-parallel mechanism, composed of a parallel four-bar mechanism and a parallel mechanism. The degree of freedom of the parallel mechanism is calculated by using the modified Grübler-Kutzbach criterion, the result shows that the parallel mechanism’s degree of freedom is greater than the number of the active inputs, so the motion of the parallel mechanism can not be determined directly. The reason is that the yawing motion law of the 4S closed-loop within the mechanism is not unique, so optimization analysis of the 4S closed-loop is performed. Using rotation similarity transformation, the orientation of the output link of 4S closed-loop after the yawing motion can be described by yzy Euler angle, and the motion of the parallel mechanism is thus determined. yzyy Euler angle is used to describe the orientation of the gripper carrier, resulting in that the first three angles just describe the orientation of the output link of 4S closed-loop after the yawing motion, the relation between the active inputs and the pose of the gripper carrier is then established easily. Velocity analysis of the whole mechanism is also constructed based on the position equations, and the mechanism is simulated by ADAMS software to testify the correctness of the position and velocity analysis.

Key words: Degree of freedom, Euler angle, Forging manipulator, Position analysis, Parallel mechanism