Type Synthesis of 2T1R Planar Parallel Mechanisms and Their Moduling Development Applications

Dongsheng Zhang,Yundou Xu,Yongsheng Zhao,Yu Zheng,Jing Wu,Lei Wei

doi:10.1109/access.2021.3079266

Dongsheng Zhang, Yundou Xu + Show 4 more

Open Access

https://doi.org/10.1109/access.2021.3079266

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Abstract

The two translational degrees-of-freedom (DOF) and one rotational DOF (2T1R) planar parallel mechanisms (PMs) have the characteristics of simple structures, simple kinematic and dynamic models, and ease of control and allow for a variety of application prospects. This paper concentrates on the derivations of the 5-DOF hybrid manipulators based on the synthesized mechanisms. To understand the effect of the constraint on the motion of a rigid body clearly, the method of reciprocal product between the wrench screw (constraint) and the twist screw (motion) is used and the relationships between the constraint and the motion of a rigid body are analyzed as well. The results are extended to the relationships between the limb constraint and the axes of limb joints. Then, limbs are divided into planar motion and spatial motion limbs in view of their motion characteristics, and some common limbs with constraint are listed. After that, based on the type synthesis method, a class of 2T1R planar PMs with common limbs is carried out. Meanwhile, some typical planar closed chains with two same limbs are obtained in the process of type synthesis. Finally, a 2T1R kinematically redundancy planar PM and two 2R1T spatial PMs are derived by making simple changes to the obtained mechanisms, and detailed derivations of three 5-DOF hybrid manipulators with the ability of processing spatial complex surface are given. Proved by the test parts, the accomplishment of deriving novel robot configurations with regard to expectant motion are quite valuable and practical.

Highlights

Industrial robots are most successful in applications like pick and place, motion simulation, and machine processing, etc [1]–[3]
In this paper, the reciprocal product method based on screw theory is used to analyze the effect of the limb constraint on the motion of the moving platform (MP)
To construct 2T1R planar parallel mechanisms (PMs), some common limbs with constraint are classified into planar motion limbs and spatial motion limbs

Summary

INTRODUCTION

Industrial robots are most successful in applications like pick and place, motion simulation, and machine processing, etc [1]–[3]. TYPE SYNTHESIS OF 2T1R PLANAR PMS BASED ON CONSTRAINT FORCE/TORQUE Screw theory as a common mathematical tool has been widely used in the constraint and motion analysis of spatial PMs. Vectors expressed by screws contain the position and orientation information. C. TYPE SYNTHESIS OF 2T1R PLANAR PM For a general 2T1R PM, according to the limb constraint and space geometry theory, we know that the axis of rotational DOF is perpendicular to the axes of translational DOF. There are really certain connections among different types of 3-DOF 2T1R planar PMs. In summary, from the preceding analysis, we know that the type synthesis method based on the limb constraint and space geometry theory is quite intuitive and convenient.

DEVELOPMENT APPLICATIONS OF THE PLANAR CLOSED CHAINS

CONCLUSION