Topological Analysis of a Partially Decoupled 3T1R Parallel Mechanism with Zero Coupling Degree

Type Synthesis of 1T2R Parallel Mechanisms Using Structure Coupling-Reducing Method

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-019-0403-1 ◽

2019 ◽

Vol 32 (1) ◽

Author(s):

Haitao Liu ◽

Ke Xu ◽

Huiping Shen ◽

Xianlei Shan ◽

Tingli Yang

Keyword(s):

Explicit Form ◽

Parallel Mechanism ◽

Analytic Solutions ◽

Forward Kinematics ◽

Parallel Mechanisms ◽

Type Synthesis ◽

Real Time Control ◽

Time Control ◽

Topological Characteristics ◽

Zero Coupling

Abstract Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms. Therefore, the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest. Based on this purpose, this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism. With the aid of the theory of mechanism topology, the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented, which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism. Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed, resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree. One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics. The process of type synthesis is in the order of permutation and combination; therefore, there are no omissions. This method is also applicable to other configurations, and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method.

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Topological Design of an Asymmetric 3-Translational Parallel Mechanism With Zero Coupling Degree and Motion Decoupling

Volume 5A: 42nd Mechanisms and Robotics Conference ◽

10.1115/detc2018-85709 ◽

2018 ◽

Author(s):

Huiping Shen ◽

Chengqi Wu ◽

Damien Chablat ◽

Guanglei Wu ◽

Ting-li Yang

Keyword(s):

Parallel Mechanism ◽

Design Theory ◽

Analytical Formula ◽

Inverse Kinematic ◽

Topology Design ◽

Kinematic Chains ◽

Topological Design ◽

Decoupled Motion ◽

Topological Characteristics ◽

Zero Coupling

In this paper a new asymmetric 3-translational (3T) parallel manipulator, i.e., RPa(3R) 2R+RPa, with zero coupling degree and decoupled motion is firstly proposed according to topology design theory of parallel mechanism (PM) based on position and orientation characteristics (POC) equations. The main topological characteristics such as POC, degree of freedom and coupling degree are calculated. Then, the analytical formula for the direct and inverse kinematic are directly derived since coupling degree of the PM is zero. The study of singular configurations is simple because of the independence of the kinematic chains.

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