Design and analysis of a class of two-limb non-parasitic 2T1R parallel mechanism with decoupled motion and symbolic forward position solution - influence of optimal arrangement of limbs onto the kinematics, dynamics and stiffness

Abstract

The two-limb11Throughout this paper, the two-limb parallel mechanism means that the base and moving platforms of a parallel mechanism are directly connected with two independent limbs, despite the existence of closed sub-loop in one limb (i.e., in this work, it is named as hybrid-single-ordered-chain, and HSOC for short). parallel mechanisms (PMs) can have the advantages, in terms of avoidance of mechanical collision, simple architecture, rapid configuration transformation and large workspace volume. This paper consists of two major contents. The first aspect pertains to the design of a class of two-limb PMs with two translations and one rotation (2T1R), where a family of PMs featuring two translations actuated by sliding units are proposed, with decoupled position and orientation as well as symbolic forward position solution, without parasitic motions. The second aspect is to analyze the influence of the arrangement of limbs onto the kinematic, dynamic and stiffness performance of the PMs. Using the kinematic modeling method based on topological characteristics, the unified symbolic forward and inverse position solutions of the PMs are derived, together with the workspace, rotational capacity and singularity. Finally, a comparative study regarding the kinematics, dynamics and stiffness of the two PMs is carried out to find the optimal PM configuration. This paper presents a systematic analysis for the synthesis, optimal design and performance evaluation of two-limb parallel mechanisms.