Dynamics evaluation of parallel manipulators considering gravity and driving force uniformity

2020 ◽  
Vol 234 (16) ◽  
pp. 3143-3153
Author(s):  
Liping Wang ◽  
Dong Wang ◽  
Jun Wu
Keyword(s):  
Driving Force ◽  
Parallel Manipulator ◽  
Evaluation Method ◽  
Mass Matrix ◽  
Parallel Manipulators ◽  
Evaluation Methods ◽  
General Evaluation ◽  
High Acceleration ◽  
General Dynamics ◽  
Evaluation Work

Dynamics evaluation is one of the core research contents of robotics, especially for the parallel manipulators, which are usually working with high acceleration. The general dynamics evaluation methods mainly deal with the acceleration of end-effector and magnitude of driving force based on the general inertia/mass matrix, and ignore the gravity. However, with the change of the placement mode of a parallel manipulator, the gravity would have a great effect on the dynamics of a heavy parallel manipulator. On the other hand, there still some other properties should be evaluated, such as the acceleration sensitivity of each driving shaft caused by gravity, the driving force uniformity when driving force achieves its maximum value. For these reasons, this paper investigates a dynamics evaluation method considering gravity and driving force uniformity. First, the limitations of general evaluation methods are described; next, the proposed dynamics evaluation method is given, including acceleration sensitivity analysis and the driving force uniformity; finally, by taking a typical horizontal parallel tool head as an example of study, a complete dynamics evaluation work is performed by using the proposed method.

An Effective Approach to Model Parallel Robots With Flexible Links

2021 ◽  
Author(s):  
Brillarelli Stefano ◽  
Matteo-Claudio Palpacelli
Keyword(s):  
Software Architecture ◽  
Parallel Manipulator ◽  
Path Following ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Flexible Links ◽  
Model Based Control ◽  
High Acceleration ◽  
Control Schemes ◽  
Pick And Place

Abstract This paper is focused on the development of an effective hardware and software architecture that is useful to improve the performance of slender parallel manipulators. The latter can perform high acceleration in fast pick and place applications, but their features can be also exploited in more advanced operations, where path following is a central issue. A simple and effective approach to model the elastodynamic behavior of flexible parallel manipulator is proposed, conceived to be fast and easy to implement in model-based control schemes. Moreover, a workbench architecture based on camera acquisitions is essential to calibrate the elastodynamic model and provide all the required information that are needed to improve path following of flexible mechanims.

Optimum design of a 4-PSS-PU redundant parallel manipulator based on kinematics and dynamics

2015 ◽  
Vol 230 (13) ◽  
pp. 2273-2284 ◽  
Author(s):  
Liping Wang ◽  
Binbin Zhang ◽  
Jun Wu
Keyword(s):  
Optimum Design ◽  
Parallel Manipulator ◽  
Design Space ◽  
Jacobian Matrix ◽  
Parallel Manipulators ◽  
Search Method ◽  
Kinematics And Dynamics ◽  
Performance Indices ◽  
Maximum Acceleration ◽  
High Acceleration

This paper presents an optimum design of a 4-PSS-PU redundant parallel manipulator by taking the workspace, conditioning performance, and acceleration into account. On the basis of rank of the Jacobian matrix, a method to directly find out the workspace is presented, rather than the search method. Based on the dynamic model, a maximum acceleration index is defined. The corresponding atlases of these performance indices are represented graphically in the established design space. Based on these atlases, the optimum design is performed and the optimum region is determined. It is expected to realize the high acceleration of parallel manipulators by using the optimum method.

Kinematic analysis and workspace determination of hexarot-a novel 6-DOF parallel manipulator with a rotation-symmetric arm system

Robotica ◽  
2014 ◽  
Vol 33 (08) ◽  
pp. 1686-1703 ◽  
Author(s):  
Mohammad Reza Chalak Qazani ◽  
Siamak Pedrammehr ◽  
Arash Rahmani ◽  
Behzad Danaei ◽  
Mir Mohammad Ettefagh ◽  
...  
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Forward Kinematics ◽  
Parallel Mechanisms ◽  
End Effector ◽  
High Acceleration ◽  
Workspace Analysis ◽  
Rotation Symmetric ◽  
Cloud Of Points

SUMMARYParallel mechanisms possess several advantages such as the possibilities for high acceleration and high accuracy positioning of the end effector. However, most of the proposed parallel manipulators suffer from a limited workspace. In this paper, a novel 6-DOF parallel manipulator with coaxial actuated arms is introduced. Since parallel mechanisms have more workspace limitations compared to that of serial mechanisms, determination of the workspace in parallel manipulators is of the utmost importance. For finding position, angular velocity, and acceleration, in this paper, inverse and forward kinematics of the mechanism are studied and after presenting the workspace limitations, workspace analysis of the hexarot manipulator is performed by using MATLAB software. Next, using the obtained cloud of points from simulation, the overall borders of the workspace are illustrated. Finally, it is shown that this manipulator has the important benefits of combining a large positional workspace in relation to its footprint with a sizable range of platform rotations.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

Research and Evaluation of Bionics Shape Design Based on Cases

2014 ◽  
Vol 551 ◽  
pp. 621-625
Author(s):  
Nan Chu Guo
Keyword(s):  
Genetic Algorithm ◽  
Quantitative Methods ◽  
Evaluation Method ◽  
Evaluation Methods ◽  
Shape Design ◽  
Fuzzy Evaluation ◽  
Ideal Approach ◽  
Comprehensive Fuzzy Evaluation

The paper proposes an ideal approach of shape design by using shape evaluation methods accurately. The paper proposes and tests the comprehensive fuzzy evaluation method using a case of two clips based on genetic algorithm and quantitative methods. By using this evaluation method, the shape details of a product could be improved gradually.

Structure Synthesis of 3-RRS Type Spatial Compliant Parallel Manipulator

2010 ◽  
Vol 44-47 ◽  
pp. 1375-1379
Author(s):  
Da Chang Zhu ◽  
Li Meng ◽  
Tao Jiang
Keyword(s):  
Parallel Manipulator ◽  
Compliant Mechanisms ◽  
Screw Theory ◽  
Weight Ratio ◽  
Parallel Manipulators ◽  
Robot System ◽  
New Approach ◽  
Structure Synthesis ◽  
Rigid Joints ◽  
Type 3

Parallel manipulators has been extensively studied by virtues or its high force-to-weight ratio and widely spread applications such as vehicle or flight simulator, a machine tool and the end effector of robot system. However, as each limb includes several rigid joints, assembling error is demanded strictly, especially in precision measurement and micro-electronics. On the other hand, compliant mechanisms take advantage of recoverable deformation to transfer or transform motion, force, or energy and the benefits of compliant mechanisms mainly come from the elimination of traditional rigid joints, but the traditional displacement method reduce the stiffness of spatial compliant parallel manipulators. In this paper, a new approach of structure synthesis of 3-DoF rotational compliant parallel manipulators is proposed. Based on screw theory, the structures of RRS type 3-DoF rotational spatial compliant parallel manipulator are developed. Experiments via ANSYS are conducted to give some validation of the theoretical analysis.

Based on the Fuzzy Multi-Objective People Decision Method of Engineering Bidding Evaluation

2013 ◽  
Vol 671-674 ◽  
pp. 3147-3151
Author(s):  
Yun Na Wu ◽  
Chao Liu ◽  
Mandula Naren ◽  
He Ping Wang ◽  
Jian Chen
Keyword(s):  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Evaluation Methods ◽  
Actual Case ◽  
Engineering Construction ◽  
Comprehensive Evaluation Method ◽  
Multi Objective ◽  
Bidding Price ◽  
Weight Method ◽  
Conducting Research

The construction project bidding is a feasible method in engineering transactions and the main competition form of the construction activities under the conditions of the market economy. The bid assessment is an important link of bidding, and whether bid evaluation method is scientific or not, is directly related to the success of the tender. In the engineering construction field, at present the current commonly used evaluation methods are the comprehensive evaluation method and the lowest bidding price evaluation method. Based on fuzzy set theory and multi-objective people decision theory, we introduce fuzzy multi-objective people decision-making evaluation methods. And conducting research to put forward the evaluation index and weight method to determine the bidding decision model. Finally we apply it to actual case to make out the more standardized and scientific bidding evaluation method.

Effect of links deformation on motion precision of parallel manipulator based on flexible dynamics

2017 ◽  
Vol 44 (6) ◽  
pp. 776-787 ◽  
Author(s):  
Chunxia Zhu ◽  
Jay Katupitiya ◽  
Jing Wang
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Beam Theory ◽  
Parallel Manipulators ◽  
Dynamic Responses ◽  
Axial Deformation ◽  
Content Type ◽  
High Performing ◽  
Coupling Equations ◽  
The Relationship

Purpose Manipulator motion accuracy is a fundamental requirement for precision manufacturing equipment. Light weight manipulators in high speed motions are vulnerable to deformations. The purpose of this work is to analyze the effect of link deformation on the motion precision of parallel manipulators. Design/methodology/approach The flexible dynamics model of the links is first established by applying the Euler–Bernoulli beam theory and the assumed modal method. The rigid-flexible coupling equations of the parallel mechanism are further derived by using the Lagrange multiplier approach. The elastic energy resulting from spiral motion and link deformations are computed and analyzed. Motion errors of the 3-link torque-prismatic-torque parallel manipulator are then evaluated based on its inverse kinematics. The validation experiments are also conducted to verify the numerical results. Findings The lateral deformation and axial deformation are largest at the middle of the driven links. The axial deformation at the middle of the driven link is approximately one-tenth of the transversal deformation. However, the elastic potential energy of the transversal deformation is much smaller than the elastic force generated from axial deformation. Practical implications Knowledge on the relationship between link deformation and motion precision is useful in the design of parallel manipulators for high performing dynamic responses. Originality/value This work establishes the relationship between motion precision and the amount of link deformation in parallel manipulators.

scholarly journals Workspace Delineation of Cable-Actuated Parallel Manipulators

2004 ◽  
Author(s):  
Ethan Stump ◽  
Vijay Kumar
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Extensive Literature ◽  
Reachable Workspace ◽  
Planar Parallel Manipulator ◽  
Analytic Expressions

While there is extensive literature available on parallel manipulators in general, there has been much less attention given to cable-driven parallel manipulators. In this paper, we address the problem of analyzing the reachable workspace using the tools of semi-definite programming. We build on earlier work [1, 2] done using similar techniques by deriving limiting conditions that allow us to compute analytic expressions for the boundary of the reachable workspace. We illustrate this computation for a planar parallel manipulator with four actuators.

scholarly journals Regions of Feasible Point-to-Point Trajectories in the Cartesian Workspace of Fully-Parallel Manipulators

1999 ◽  
Author(s):  
Damien Chablat ◽  
Philippe Wenger
Keyword(s):  
Parallel Manipulator ◽  
Cartesian Product ◽  
Parallel Manipulators ◽  
Joint Space ◽  
Inverse Kinematic ◽  
Connected Components ◽  
Feasible Point ◽  
Cartesian Space ◽  
Point Trajectories ◽  
Point To Point

Abstract The goal of this paper is to define the n-connected regions in the Cartesian workspace of fully-parallel manipulators, i.e. the maximal regions where it is possible to execute point-to-point motions. The manipulators considered in this study may have multiple direct and inverse kinematic solutions. The N-connected regions are characterized by projection, onto the Cartesian workspace, of the connected components of the reachable configuration space defined in the Cartesian product of the Cartesian space by the joint space. Generalized octree models are used for the construction of all spaces. This study is illustrated with a simple planar fully-parallel manipulator.

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