scholarly journals Analysis of rotation capacity of a novel 2R1T mechanism based on origami of thick panels

2021 ◽  
Vol 2125 (1) ◽  
pp. 012044
Author(s):  
Boyan Chang ◽  
Jifu Zhang ◽  
Dong Liang ◽  
Yang Zhou
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Engineering Application ◽  
Base Plate ◽  
Rotational Angle ◽  
Rotation Capacity ◽  
Structural Variables ◽  
Lower Mobility ◽  
Translational Degree ◽  
Moving Platform

Abstract A foldable and symmetrical lower-mobility parallel mechanism was proposed based on Waterbomb origami of thick panels. It consists of a moving platform, a base plate and three deployable foldable legs between moving platform and base plate. Firstly, constraint wrenches of each leg were formulated based on screw theory and the results illustrated that the moving platform is in possession of two degrees of orientation freedom and one translational degree of freedom. Secondly, it was approved that base and moving platform are always symmetrical about a middle plane and the moving platform can rotate continuously about any axis chosen freely on this plane. Solving models including forward and inverse position problems were established to determine the maximum rotational angle and workspace. Finally, performance indexe of maximum rotational angle of the PM was analyzed, and effects of two structural variables to the performance were summarized. Conclusions obtained can provide a theoretical basis for the structural design and engineering application of this 2T1R parallel mechanism.

Actuating Input Selection of 5-UPS/PRPU Parallel Machine Tool

2005 ◽  
Author(s):  
Jian-She Gao ◽  
Ren-Cheng Zheng ◽  
Yong-Sheng Zhao
Keyword(s):  
Parallel Mechanism ◽  
Basic Problem ◽  
Screw Theory ◽  
Parallel Machine ◽  
Condition Numbers ◽  
Constraint Matrix ◽  
Input Selection ◽  
Moving Platform ◽  
Parallel Machine Tool ◽  
Selection Of

The actuating input selection is an important basic problem for the parallel mechanism. Based on the screw theory, the constraint screw can be got after locking a kinematic pair in any limb, which can be taken as actuating wrench acted on the moving platform of the parallel mechanism. The constraint screw matrix is composed of the structure constraint screws and the constraint screws of the actuating pairs. The reasonableness of input selection can be judged by the rank of the constraint matrix. The performance of the combinations of actuating inputs is evaluated by the condition numbers of the force constraint matrix and the torque constraint matrix respectively. The theory presented is validated by the simulation and the maching test.

Analysis and Design of Lower-Mobility Parallel Mechanism of Non-Symmetrical Based on Variable Topology Theory

2011 ◽  
Vol 201-203 ◽  
pp. 1907-1912
Author(s):  
Rong Jiang Cui ◽  
Zong He Guo ◽  
Zi Xun Yin ◽  
Song Song Zhu
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Basic Variable ◽  
Analysis And Design ◽  
And Topology ◽  
Variable Topology ◽  
Lower Mobility ◽  
Branched Chain ◽  
Mechanism Theory

First, the branched-chain of parallel mechanism was Classified according to reciprocal screw theory. Then, the introduction of variable topology mechanism theory, with the characteristics of parallel mechanisms themselves, the definition and basic variable topology means of variable topology parallel mechanism were given. With evolutionary theory, the method to design lower-mobility parallel mechanisms of non-asymmetric was proposed based on variable topology mechanism theory .Taking 3-RPS as ideal mechanism and topology synthesis was carried out, besides 2-RPS mechanism were analyzed. The introduction of variable topology mechanism theory provided a theoretical basis and innovative approaches for the synthesis configuration of Lower-mobility parallel mechanisms of non-asymmetric.

Motion/Force Transmission Analysis of Parallel Mechanisms With Planar Closed-Loop Subchains

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Kristan Marlow ◽  
Mats Isaksson ◽  
Jian S. Dai ◽  
Saeid Nahavandi
Keyword(s):  
Performance Measures ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Force Transmission ◽  
Six Degrees Of Freedom ◽  
Lower Mobility ◽  
Transmission Ability

Singularities are one of the most important issues affecting the performance of parallel mechanisms. A parallel mechanism with less than six degrees of freedom (6DOF) is classed as having lower mobility. In addition to input–output singularities, such mechanisms potentially suffer from singularities among their constraints. Furthermore, the utilization of closed-loop subchains (CLSCs) may introduce additional singularities, which can strongly affect the motion/force transmission ability of the entire mechanism. In this paper, we propose a technique for the analysis of singularities occurring within planar CLSCs, along with a finite, dimensionless, frame invariant index, based on screw theory, for examining the closeness to these singularities. The integration of the proposed index with existing performance measures is discussed in detail and exemplified on a prototype industrial parallel mechanism.

Design and Kinematics Analysis of a Novel Planar Parallel Mechanism

2014 ◽  
Vol 568-570 ◽  
pp. 904-910
Author(s):  
Yan Bin Zhang ◽  
Hui Ping Wang
Keyword(s):  
Condition Number ◽  
Parallel Mechanism ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Kinematics Analysis ◽  
Moving Platform ◽  
One To One ◽  
Actuated Joints

A novel 3-dof planar parallel mechanism, which is composed by three different limbs, is designed. The moving platform can translate along two directions and rotate around one axis with respect to the base. Mobility of the mechanism is discussed and calculated based on the screw theory. The forward and the inverse analytical position equations are derived and the veloctiy analysis is addressed too. The Jacobian matrix is an identical one, so there exists one-to-one corresponding linear controlling relationship between one of the actuated joints and one of the outputs of the platform. Moreover, the condition number of the Jacobian matrix is constantly equal to one and the mechanism shows fully-isotropic throughout entire workspace.

scholarly journals A New Metamorphic Parallel Leg Mechanism with Reconfigurable Moving Platform

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yong Xu ◽  
Zheng Liang ◽  
Jiali Liu
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Walking Robots ◽  
Metamorphic Mechanism ◽  
Parallel Leg Mechanism ◽  
Moving Platform ◽  
Configuration Synthesis

This paper proposes the concept of full configuration state of metamorphic mechanism. Based on the concept, the configuration synthesis principle of metamorphic parallel mechanism is put forward. Firstly, a metamorphic parallel mechanism in full configuration state is synthesized, and then full configuration state evolves into a specific configuration state by increasing constraints or decreasing degrees of freedom. A reconfigurable moving platform based on the triple symmetric Bricard spatial closed-loop mechanism with a single degree of freedom is proposed. Based on this, a new method for switching motion configuration states of the metamorphic parallel mechanism is constructed. According to the configuration synthesis principle presented above, a novel metamorphic parallel mechanism that can switch between three- and four-degree-of-freedom is synthesized, and then the triple symmetric Bricard spatial closed-loop mechanism is used as the reconfigurable moving platform (that is, the reconfigurable foot of a walking robot) of the metamorphic mechanism, and thus, a novel metamorphic parallel leg mechanism is created. The screw theory is used to verify the degrees of freedom of the new type of metamorphic parallel leg. The proposed metamorphic parallel leg mechanism is expected to improve flexibility and adaptability of walking robots in unstructured environment.

scholarly journals Kinematic analysis of a novel 3-CRU translational parallel mechanism

2015 ◽  
Vol 6 (1) ◽  
pp. 57-64 ◽  
Author(s):  
B. Li ◽  
Y. M. Li ◽  
X. H. Zhao ◽  
W. M. Ge
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Structural Characteristics ◽  
Parallel Mechanisms ◽  
Reachable Workspace ◽  
Potential Applications ◽  
Moving Platform ◽  
And Performance

Abstract. In this paper, a modified 3-DOF (degrees of freedom) translational parallel mechanism (TPM) three-CRU (C, R, and U represent the cylindrical, revolute, and universal joints, respectively) structure is proposed. The architecture of the TPM is comprised of a moving platform attached to a base through three CRU jointed serial linkages. The prismatic motions of the cylindrical joints are considered to be actively actuated. Kinematics and performance of the TPM are studied systematically. Firstly, the structural characteristics of the mechanism are described, and then some comparisons are made with the existing 3-CRU parallel mechanisms. Although these two 3-CRU parallel mechanisms are both composed of the same CRU limbs, the types of freedoms are completely different due to the different arrangements of limbs. The DOFs of this TPM are analyzed by means of screw theory. Secondly, both the inverse and forward displacements are derived in closed form, and then these two problems are calculated directly in explicit form. Thereafter, the Jacobian matrix of the mechanism is derived, the performances of the mechanism are evaluated based on the conditioning index, and the performance of a 3-CRU TPM changing with the actuator layout angle is investigated. Thirdly, the workspace of the mechanism is obtained based on the forward position analysis, and the reachable workspace volume is derived when the actuator layout angle is changed. Finally, some conclusions are given and the potential applications of the mechanism are pointed out.

scholarly journals Screw Theory Based Singularity Analysis of Lower-Mobility Parallel Robots considering the Motion/Force Transmissibility and Constrainability

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Xiang Chen ◽  
Xin-Jun Liu ◽  
Fugui Xie
Keyword(s):  
Screw Theory ◽  
Mathematical Problem ◽  
Engineering Application ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
Input And Output ◽  
Lower Mobility ◽  
Force Transmissibility ◽  
Output Constraint

Singularity is an inherent characteristic of parallel robots and is also a typical mathematical problem in engineering application. In general, to identify singularity configuration, the singular solution in mathematics should be derived. This work introduces an alternative approach to the singularity identification of lower-mobility parallel robots considering the motion/force transmissibility and constrainability. The theory of screws is used as the mathematic tool to define the transmission and constraint indices of parallel robots. The singularity is hereby classified into four types concerning both input and output members of a parallel robot, that is, input transmission singularity, output transmission singularity, input constraint singularity, and output constraint singularity. Furthermore, we take several typical parallel robots as examples to illustrate the process of singularity analysis. Particularly, the input and output constraint singularities which are firstly proposed in this work are depicted in detail. The results demonstrate that the method can not only identify all possible singular configurations, but also explain their physical meanings. Therefore, the proposed approach is proved to be comprehensible and effective in solving singularity problems in parallel mechanisms.

The Nonexistence of Three Degrees of Freedom Rotational Fully Decoupled Parallel Mechanism

2013 ◽  
Vol 284-287 ◽  
pp. 1951-1955 ◽  
Author(s):  
Yu Lei Hou ◽  
Da Xing Zeng ◽  
Yan Bin Duan ◽  
Yong Sheng Zhao
Keyword(s):  
Control System ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Structure Design ◽  
Theoretical Significance ◽  
Moving Platform ◽  
Configuration Synthesis ◽  
Three Degrees Of Freedom ◽  
Serial Mechanism

The existence of coupling makes the parallel mechanism possess some special advantages over the serial mechanism, while it is just the coupling that brings about the parallel mechanism some difficulties in kinematics and dynamic analysis, the development of control system, and the trajectory planning. Therefore the research on the decoupled parallel mechanism becomes one of the hot of the mechanism fields. While whether the parallel mechanism can realize decouple is the premise for synthesis and analysis of the parallel mechanism. Based on screw theory, the existence of the three degrees of freedom (3-DoF) rotational fully-decoupled parallel mechanism is distinguished. Then taking the 6-PUS/UPU parallel mechanism as example, the rotation angles of the moving platform are measured, which is verified the impossibility of the 3-DoF rotation decoupling. The contents of this paper should possess theoretical significance for the innovative configuration synthesis and structure design of rotational decoupled parallel mechanism.

Coupling 3-PSR/PSU 5-axis compensation mechanism for stabilized platform and its analysis

2012 ◽  
Vol 227 (7) ◽  
pp. 1619-1629 ◽  
Author(s):  
Xiao Liu ◽  
Tieshi Zhao ◽  
Erjuan Luo ◽  
Weiwei Chen ◽  
Qiuyue Pan
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Ship Motions ◽  
Equivalent Transformation ◽  
Coupling Force ◽  
Coupling Dynamics ◽  
Lower Mobility ◽  
Coupling Characteristics ◽  
Stabilized Platform

This article presents a coupling 3-PSR/PSU parallel mechanism for ship-based stabilized platform based on the coupling characteristics of the ship motions. With coupling characteristics, the goal of 3-axis drives and 5-axis compensation of the moving platform is achieved. From the screw theory, degrees-of-freedom and coupling kinematic characteristics of the mechanism are analyzed. A method for equivalent transformation of motion parameters is proposed. This presents a mapping relationship between the independent degrees-of-freedom and the coupling degrees-of-freedom. The investigations are further extended to the coupling dynamics characteristics of the mechanism. In particular, the effects produced by the coupling force/torque to the system are analyzed. Hence, taking minimum system driving force as the optimization goal, the coupling dynamic equation of the parallel mechanism is established. The numerical example reveals that this coupling parallel mechanism can be applied to the multi-axis compensation of ship-based stabilized platform. The study also enriches the application area of lower-mobility parallel mechanism.

Kinematics Simulation of Parallel Mechanism Based on ADAMS

2012 ◽  
Vol 538-541 ◽  
pp. 479-482
Author(s):  
Xin Yu Du ◽  
Hong Wei Liu
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Virtual Prototype ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
Kinematics Simulation ◽  
Spatial Parallel Mechanism ◽  
Moving Platform ◽  
Simulation Results ◽  
Position And Orientation

In this paper,a kind of 3-UPU spatial parallel mechanism is introduced. Through deep analysis of the degree-of-freedom (DoF) for the platform using screw theory， the position and orientation of the moving platform is discussed. At last, the 3D virtual prototype modeling of this 3-UPU parallel mechanism based on software ADAMS is developed; the kinematics simulation and analysis are also carried out accordingly. From the simulation results, we can see that the proposed calculation of the DoFs and kinematics analysis is correct.

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