A new 4 DOF parallel mechanism is proposed in this work. This device consists of four parallel kinematics chains and a foldable parallelogrammic platform that can be used to grasp any large or irregular-shaped object. Thus, out of 4-DOF motion space of the device, the one-DOF is used for gripping an irregular object and the other three-DOF is used for adjusting motion of the grasped object. Particularly, the three-DOF motion is restricted in the decoupled three-dimensional translational motion space in spite of revolute joint-based parallel structure. Thus, it is not only very compact, but also has distinctive feature of both grasping and micro-positioning that are one of important aspects required in real applications. In this work, we carry out the position and kinematic analysis for the mechanism, and develop the mechanism for experimental verification of its performance.
