The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints

In the traditional three DOFs (degrees of freedom) PMs (parallel manipulators), the terminal constraints are constraint forces and torques. A recent study showed that the terminal constraints of some three DOFs PMs are screw-type constraints. However, determining the mobility of this class of PMs re...

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Main Authors: Bo Hu, Peng Bai
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/7/3572
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author Bo Hu
Peng Bai
author_facet Bo Hu
Peng Bai
author_sort Bo Hu
collection DOAJ
description In the traditional three DOFs (degrees of freedom) PMs (parallel manipulators), the terminal constraints are constraint forces and torques. A recent study showed that the terminal constraints of some three DOFs PMs are screw-type constraints. However, determining the mobility of this class of PMs remains challenging. In order to solve the above problems, this paper discusses the mobility of PMs having independent screw-type terminal constraints by introducing the principal screws. Firstly, taking a 3-CCR (C: cylindrical joint, R: revolute joint) PM as an example, the problem of identifying the mobility of PMs having screw-type constraints is proposed. Secondly, combined with the analytical expression of the terminal constraint and theory of quadratic curve decomposition, the mobility determination approach is given. Finally, a numerical example for solving the principal screws and determining the mobility of the 3-CCR PM is provided. Furthermore, the axodes of four poses with three helical DOFs and four poses with three rotational DOFs were plotted. The results show that there is a special phenomenon in which three rotational DOFs and three helical DOFs exist alternately in the workspace of this PM. This paper provides a method for directly identifying the independent helical DOFs in parallel manipulators and for studying the distribution of helical DOFs within the workspace.
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spelling doaj-art-aec863aaa4bf4242bb549dc9a93068f22025-08-20T03:08:44ZengMDPI AGApplied Sciences2076-34172025-03-01157357210.3390/app15073572The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal ConstraintsBo Hu0Peng Bai1School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, ChinaSchool of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, ChinaIn the traditional three DOFs (degrees of freedom) PMs (parallel manipulators), the terminal constraints are constraint forces and torques. A recent study showed that the terminal constraints of some three DOFs PMs are screw-type constraints. However, determining the mobility of this class of PMs remains challenging. In order to solve the above problems, this paper discusses the mobility of PMs having independent screw-type terminal constraints by introducing the principal screws. Firstly, taking a 3-CCR (C: cylindrical joint, R: revolute joint) PM as an example, the problem of identifying the mobility of PMs having screw-type constraints is proposed. Secondly, combined with the analytical expression of the terminal constraint and theory of quadratic curve decomposition, the mobility determination approach is given. Finally, a numerical example for solving the principal screws and determining the mobility of the 3-CCR PM is provided. Furthermore, the axodes of four poses with three helical DOFs and four poses with three rotational DOFs were plotted. The results show that there is a special phenomenon in which three rotational DOFs and three helical DOFs exist alternately in the workspace of this PM. This paper provides a method for directly identifying the independent helical DOFs in parallel manipulators and for studying the distribution of helical DOFs within the workspace.https://www.mdpi.com/2076-3417/15/7/3572mobility analysisparallel manipulatorscrew-type terminal constraint
spellingShingle Bo Hu
Peng Bai
The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
Applied Sciences
mobility analysis
parallel manipulator
screw-type terminal constraint
title The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
title_full The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
title_fullStr The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
title_full_unstemmed The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
title_short The Mobility Analysis of a 3-CCR Parallel Manipulator with Three Screw-Type Terminal Constraints
title_sort mobility analysis of a 3 ccr parallel manipulator with three screw type terminal constraints
topic mobility analysis
parallel manipulator
screw-type terminal constraint
url https://www.mdpi.com/2076-3417/15/7/3572
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