Some New Parallel Mechanisms Containing the Planar Four-Bar Parallelogram

A parallelogram allows the output link to remain at a fixed orienta-tion with respect to an input link, for which it acts as a unique role in the design of parallel mechanisms. In this paper, the unique role of a parallelogram is used completely to design some new paral-lel mechanisms with two to six degrees of freedom (DoFs). In these mechanisms, some with three DoFs possess the advantage of very high rotational capability and some with two DoFs have the trans-lational output of a rigid body. More than that, the design concept is also applied first to some parallel mechanisms to improve the sys-tems ’ rotational capability. The parallel mechanisms proposed in this paper have wide applications in industrial robots, simulators, micromanipulators, parallel kinematics machines, and any other ma-nipulation devices in which high rotational capability and stiffness are needed. Especially, the paper provides new concepts of the de-sign of novel parallel mechanisms and the improvement of rotational capability for such systems. KEY WORDS—parallel mechanism, degrees of freedom, ro-tational capability, mechanical design, parallelogram 1