Type synthesis of single-loop 3T1R-parallel mechanisms with a multi-DOF drive system

Abstract

This paper systematically develops the type synthesis of single-loop parallel mechanisms (PMs) with three translations (T) along three independent directions and one rotation (R) around one fixed direction (3T1R-PMs). Each limb is driven by a multi-degree of freedom (DOF) drive system, and the output link can generate large rotational angle. Based on previously presented multi-DOF drive systems (DSs), a novel systematic method is proposed to synthesize single-loop 3T1R-PMs based on Lie group theory. To improve the rotation function of the single-loop 3T1R-PM, two types of connecting styles between the output link and the ends of two limbs are introduced to construct the single-loop 3T1R-PM with a full circle rotation function. A class of single-loop 3T1R-PM with two serial limbs driven by a 2-DOF driver and a class of single-loop 3T1R-PM with a hybrid limb driven by a 3-DOF DS and a serial limb driven by a 1-DOF joint are constructed. Moreover, the simulations are implemented to display large pose operation capability of two examples of presented 3T1R-PMs.