THE PROPERTIES OF THE MECHANISMS WITH SIX DEGREES OF FREEDOM

2021 ◽  
pp. 28-33
Author(s):  
S. V. Kheylo ◽  
O. A. Garin ◽  
S. V. Palochkin ◽  
S. D. Dorofeev
Keyword(s):  
Degrees Of Freedom ◽  
The Novel ◽  
Parallel Mechanisms ◽  
Kinematic Scheme ◽  
Output Link ◽  
Kinematic Chains ◽  
Analysis And Design ◽  
Six Degrees Of Freedom ◽  
Robotic Assisted Surgery ◽  
Coupling Equations

Parallel mechanisms analysis and design are the main trends of advance robotic engineering. This article is devoted to the novel parallel mechanisms with six degrees of freedom. The presented mechanisms can be applied in additive technologies, robotic–assisted surgery. The proposed mechanisms contain six drives and six kinematic chains. They have the properties of a partial kinematic decoupling, which allows realized separately translational and rotational movements. The presented mechanisms is a simple kinematic scheme. The drives can provide a ratio 1:1 of with the movement of the output link. The paper considers the solution of kinematics problems, velocity analysis, singularities. The velocity problem is solved by differentiating the coupling equations. Singularities were detected by studying the properties of Jacobi matrices. The singularities depend only on the orientation of the output link. These mechanisms have a large working area free of singularities. The working area is determined by solving the coupling equations. The solved problems allow to solve the control such mechanisms in the future.

Construction of a Six-Degrees-of-Freedom Parallel Manipulator With Three Planarly Actuated Links

1996 ◽  
Author(s):  
Ronen Ben-Horin ◽  
Moshe Shoham
Keyword(s):  
Parallel Manipulator ◽  
High Performance ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Simple Design ◽  
Output Link ◽  
Coordinated Motion ◽  
Six Degrees Of Freedom ◽  
Work Volume ◽  
New Type

Abstract The construction of a new type of a six-degrees-of-freedom parallel robot is presented in this paper. Coordinated motion of three planar motors, connected to three fixed-length links, produces a six-degrees-of-freedom motion of an output link. Its extremely simple design along with much larger work volume make this high performance-to-simplicity ratio robot very attractive.

scholarly journals Reconfiguration Analysis of a 3-DOF Parallel Mechanism

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 66
Author(s):  
Maurizio Ruggiu ◽  
Xianwen Kong
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Operation Mode ◽  
Parallel Mechanisms ◽  
Universal Joint ◽  
Kinematic Chains ◽  
Constraint Equations ◽  
The Third ◽  
Equilateral Triangles ◽  
Moving Platform

This paper deals with the reconfiguration analysis of a 3-DOF (degrees-of-freedom) parallel manipulator (PM) which belongs to the cylindrical parallel mechanisms family. The PM is composed of a base and a moving platform shaped as equilateral triangles connected by three serial kinematic chains (legs). Two legs are composed of two universal (U) joints connected by a prismatic (P) joint. The third leg is composed of a revolute (R) joint connected to the base, a prismatic joint and universal joint in sequence. A set of constraint equations of the 1-RPU−2-UPU PM is derived and solved in terms of the Euler parameter quaternion (a.k.a. Euler-Rodrigues quaternion) representing the orientation of the moving platform and of the Cartesian coordinates of the reference point on the moving platform. It is found that the PM may undergo either the 3-DOF PPR or the 3-DOF planar operation mode only when the base and the moving platform are identical. The transition configuration between the operation modes is also identified.

Designing Statically Determinable Mechanisms of Technological Mechatronic Machines with Parallel Kinematics

2019 ◽  
Vol 20 (7) ◽  
pp. 428-436
Author(s):  
A. K. Tolstosheev ◽  
V. A. Tatarintsev
Keyword(s):  
Structural Analysis ◽  
Hierarchical Structure ◽  
Degrees Of Freedom ◽  
Kinematic Chain ◽  
Parallel Structure ◽  
Parallel Kinematics ◽  
Output Link ◽  
Parallel Connection ◽  
Kinematic Chains ◽  
Chain Increase

The work is devoted to improving the reliability and manufacturability of mechatronic machine designs with parallel kinematics by replacing statically indeterminable manipulators with statically determinable mechanisms. A technique is proposed in which the design of statically determinable manipulators of technological mechatronic machines with parallel kinematics is performed by modifying the structure of prototypes and includes three steps: identifying and analyzing redundant links, eliminating redundant links, checking the correctness of eliminating redundant links. To determine the number of degrees of freedom of the mechanism, identify redundant links, and verify the solution, the authors use the proposed methodology for structural analysis of parallel structure mechanisms. In structural analysis, a manipulator is represented by a hierarchical structure and is considered as a parallel connection of elementary mechanisms with an open kinematic chain; as a kinematic chain consisting of leading and driven parts; as a set of links and kinematic pairs; as a kinematic connection of the output link and the rack. The article implements the following techniques for eliminating redundant links: mobility increase in kinematic pairs; introduction of unloading links and passive kinematic pairs to the kinematic chain; exclusion of extra links and pairs from the kinematic chain; increase in mobility in some kinematic pairs simultaneously with the exclusion of other kinematic pairs that have become superfluous. The authors developed several variants of structural schemes of self-aligning manipulators based on the Orthoglide mechanism, which retain the basic functional proper ties of the prototype. To increase the number of self-aligning mechanism diagrams, the redistribution of mobilities and links within the connecting kinematic chain and between connecting kinematic chains is used. The proposed methodics allow to determine the number of degrees of freedom of the mechanism, the number and type of redundant links, eliminate redundant links and, on an alternative basis, build structural diagrams of statically determinable mechanisms of technological mechatronic machines with parallel kinematics.

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.

An Analytical Model for Calculating the Workspace of a Flexure Hexapod Nanopositioner

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Hongliang Shi ◽  
Hai-Jun Su
Keyword(s):  
Analytical Model ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Parallel Mechanisms ◽  
Torsion Angles ◽  
Maximum Deformation ◽  
Practical Applications ◽  
Six Degrees Of Freedom ◽  
Workspace Analysis ◽  
Flexure Joints

This paper presents an analytical model for calculating the workspace of a flexure-based hexapod nanopositioner previously built by the National Institute of Standards and Technology (NIST). This nanopositioner is capable of producing high-resolution motions in six degrees of freedom by actuating linear actuators on a planar tri-stage. However, the workspace of this positioner is still unknown, which limits its uses in practical applications. In this work, we seek to derive a kinematic model for predicting the workspace of such kinds of flexure based platforms by assuming that their workspace is mainly constrained by the deformation of flexure joints. We first study the maximum deformation including bending and torsion angles of an individual flexure joint. We then derive the inverse kinematics and calculation of bending and torsion angles of each wire flexure in the overall mechanism with given position of the top platform center of the hexapod nanopositioner. At last, we compare results with finite element models of the entire platform. This model is beneficial for workspace analysis and optimization for design of compliant parallel mechanisms.

Geometric synthesis of spatial parallel manipulators with fewer than six degrees of freedom

2002 ◽  
Vol 216 (12) ◽  
pp. 1175-1185 ◽  
Author(s):  
T S Zhao ◽  
J S Dai ◽  
Z Huang
Keyword(s):  
Mechanism Design ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Algebraic Approach ◽  
Structural Complexity ◽  
Parallel Manipulators ◽  
Parallel Mechanisms ◽  
Kinematic Pair ◽  
Type Synthesis ◽  
Six Degrees Of Freedom

Manipulators with fewer than six degrees of freedom meet specific tasks and have the advantage of reducing structural complexity, design redundancy and cost. In order to construct parallel manipulators for given tasks, this paper develops an algebraic approach to type synthesis of spatial parallel mechanisms with fewer than six degrees of freedom based on the screw theory. With the proposed steps (i.e. describing restraining screws, identifying basic kinematic pair (KP) screws reciprocal to the restraining screws, linearly transforming the basic KP screws to obtain equivalent serial limbs and allocating the serial limbs) new parallel mechanisms can be constructed. The approach converts a mechanism design into a screw algebra operation, in which screws describe kinematic pairs and constraints between links. As examples, synthesis procedures of parallel mechanisms with four degrees of freedom are given, from which five novel parallel mechanisms result.

An analytical approach to determine motions/constraints of serial kinematic chains based on Clifford algebra

2016 ◽  
Vol 231 (7) ◽  
pp. 1324-1338 ◽  
Author(s):  
Xinming Huo ◽  
Tao Sun ◽  
Yimin Song ◽  
Yang Qi ◽  
Panfeng Wang
Keyword(s):  
Clifford Algebra ◽  
Programming Languages ◽  
Analytical Approach ◽  
Linear Equations ◽  
Numerical Approach ◽  
Parallel Mechanisms ◽  
Algebraic Form ◽  
Kinematic Chains ◽  
Analysis And Design ◽  
Operation Rules

Determining the motions and constraints of serial kinematic chains in a concise and visual way is an inevitable step in the analysis and design of both serial and parallel mechanisms. The now most used method is the numerical approach which resorts to solving linear equations. By introducing Clifford algebra, this paper intends to propose an analytical approach to determine the unknown 6- n ( n < 6) constraints (motions) from the known n motions (constraints) of serial kinematic chains in different configurations only by drawing some auxiliary points, lines, and planes. The axes and action lines of motions and constraints are characterized by the lines that would be described by Clifford algebra. These lines can be determined analytically according to the relations among points, lines, and planes, which have been expressed by using the operation rules of Clifford algebra Cl(0, 3, 1) such as inner, outer, dual, and shuffle products. Based upon the mechanics principle that the constraint does not work on the motion, the unknown 6- n constraints (motions) of serial kinematic chains from known n motions (constraints) are determined both in an analytical algebraic form and in a visual manner. Finally, four examples are given to demonstrate how to use this approach and test its validity. The merit of this approach is beneficial to the digital analysis and design of both the serial and parallel mechanisms by means of computer and programming languages.

scholarly journals A simple and visually orientated approach for type synthesis of overconstrained 1T2R parallel mechanisms

Robotica ◽  
2018 ◽  
Vol 37 (7) ◽  
pp. 1161-1173 ◽  
Author(s):  
Tian Huang ◽  
Chenglin Dong ◽  
Haitao Liu ◽  
Tao Sun ◽  
Derek G. Chetwynd
Keyword(s):  
Degrees Of Freedom ◽  
Evaluation Criteria ◽  
Cost Effective ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Output Link ◽  
Component Design ◽  
Hybrid Module ◽  
Visual Approach ◽  
Rational Component

SUMMARYThis paper presents a simple and highly visual approach for the type synthesis of a family of overconstrained parallel mechanisms that have one translational and two rotational movement capabilities. It considers, especially, mechanisms offering the accuracy and dynamic response needed for machining applications. This family features a spatial limb plus a member of a class of planar symmetrical linkages, the latter connected by a revolute joint either to the machine frame at its base link or to the platform at its output link. Criteria for selecting suitable structures from among numerous candidates are proposed by considering the realistic practical requirements for reconfigurability, movement capability, rational component design and so on. It concludes that a few can simultaneously fulfil the proposed criteria, even though a variety of structures have been presented in the literature. Exploitation of the proposed structures and evaluation criteria then leads to a novel five degrees of freedom hybrid module named TriMule. A significant potential advantage of the TriMule over the Tricept arises because all the joints connecting the base link and the machine frame can be integrated into one single, compact part, leading to a lightweight, cost effective and flexible design particularly suitable for configuring various robotized manufacturing cells.

Kinematic Analysis and Design of a Six-Degrees of Freedom 3-RRPS Mechanism for Bone Reduction Surgery

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Terence Essomba ◽  
Sinh Nguyen Phu
Keyword(s):  
Degrees Of Freedom ◽  
Vertical Axis ◽  
Velocity Model ◽  
Analysis And Design ◽  
Six Degrees Of Freedom ◽  
Bone Fragments ◽  
Kinematic Models ◽  
Surgery First ◽  
Forward Kinematic ◽  
Classical Mechanism

Abstract Robot-assisted bone reduction surgery consists in using robots to reposition the bone fragments into their original place prior to fracture healing. This study presents the application of a 3-RRPS augmented tripod mechanism with six degrees-of-freedom for longitudinal bone reduction surgery. First, the inverse and forward kinematic models of the mechanism are investigated. Particularly, the forward kinematic is solved by applying Sylvester's dialytic method. Second, the velocity model is studied and its singular configurations are identified. The workspace of the 3-RRPS mechanism is then outlined and compared with the Stewart platform, which is a classical mechanism for the targeted application. The results show that this mechanism provides a larger workspace, especially its rotation angle about the vertical axis, which is an important aspect in the bone reduction. A series of simulations on the numerical and graphic software is performed to verify the entire analysis of the parallel mechanism. A physiguide and mscadams software are used to carry out a simulation of a real case of femur fracture reduction using the proposed mechanism to validate its suitability. Finally, a robotic prototype based on the mechanism is manufactured and experimented using an artificial bone model to evaluate the feasibility of the mechanism.

scholarly journals Design and analysis of a six degrees of freedom serial–parallel robotic mechanism with multi-degree of freedom legs

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881264
Author(s):  
Ziwei Zhang ◽  
Guoying Meng
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Simple Structure ◽  
Parallel Mechanisms ◽  
Universal Joint ◽  
Six Degrees Of Freedom ◽  
In Series ◽  
Peristaltic Movement ◽  
High Flexibility ◽  
Analytic Models

A novel mobile serial–parallel mechanism with legs for in-pipe use is proposed. The mobile robotic mechanism is composed of two identical three-universal joint–prismatic joint–universal joint parallel mechanisms connected in series and two gripping modules. The proposed parallel mechanism has two rotational freedoms and one translational freedom. In addition, the parallel mechanism can achieve continuous and equivalent rotation. The singularities of the parallel mechanism are analyzed. The overall serial–parallel mechanism has six degrees of freedom, and each gripping module has four degrees of freedom. Each parallel mechanism in the waist module is driven by three servo-electric cylinders and each leg mechanism in the gripping modules is controlled by a linear actuator. The robotic mechanism can perform peristaltic movement and turning in space. The robotic mechanism possesses a simple structure and high flexibility, along with the merits of serial–parallel mechanism. In this article, analytic models for the kinematics and dynamics of the robotic mechanism are derived. Additionally, numerical examples are given, and their solutions are validated based on results obtained by SimMechanics and Adams.

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