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.

Singularity robust inverse dynamics of planar 2-RPR parallel manipulators

2004 ◽  
Vol 218 (7) ◽  
pp. 721-730 ◽  
Author(s):  
S Kemal Ider
Keyword(s):  
Parallel Manipulator ◽  
Inverse Dynamics ◽  
Full Rank ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Dynamic Equations ◽  
Revolute Joints ◽  
Planar Parallel Manipulator ◽  
Pass Through ◽  
Full Utilization

In planar parallel robots, limitations occur in the functional workspace because of interference of the legs with each other and because of drive singularities where the actuators lose control of the moving platform and the actuator forces grow without bounds. A 2-RPR (revolute, prismatic, revolute joints) planar parallel manipulator with two legs that minimizes the interference of the mechanical components is considered. Avoidance of the drive singularities is in general not desirable since it reduces the functional workspace. An inverse dynamics algorithm with singularity robustness is formulated allowing full utilization of the workspace. It is shown that if the trajectory is planned to satisfy certain conditions related to the consistency of the dynamic equations, the manipulator can pass through the drive singularities while the actuator forces remain stable. Furthermore, for finding the actuator forces in the vicinity of the singular positions a full rank modification of the dynamic equations is developed. A deployment motion is analysed to illustrate the proposed approach.

Analysis and Validation of a Flexible Planar Two Degrees-of-Freedom Parallel Manipulator With Structural Passive Compliance

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Genliang Chen ◽  
Zhuang Zhang ◽  
Lingyu Kong ◽  
Hao Wang
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Interaction Force ◽  
Flexible Manipulator ◽  
End Effector ◽  
Flexible Links ◽  
Wide Range ◽  
Pick And Place ◽  
Passive Compliance ◽  
Large Deflection Problem

Abstract Passive compliance plays an important role in robot pick-and-place manipulation where large interaction force will be produced in response to small misalignments. In this paper, the authors report on compliance analysis and validation of a novel planar pick-and-place parallel manipulator consisting of a flexible limb. In the proposed manipulator, a planar flexible parallelogram linkage, which is coupled with a rigid one, is introduced to connect the moving and the base platforms. Since the flexible parallelogram linkage is capable of producing large deformation in both the horizontal and the vertical directions, the end effector of the manipulator can generate wide-range motions because of the flexible links. An efficient approach to the large deflection problem of flexible links is used to precisely predict the kinetostatics of the manipulator. Then, a compensation algorithm to the structural deflection of the links can be developed to actively control the position of the parallel manipulator’s end effector. The merit of the proposed flexible manipulator is its intrinsic passive compliance while performing pick-and-place tasks. A prototype is fabricated to conduct experiments for the validation of the proposed idea. The results show that the prototype has acceptable positioning accuracy, even when a large external load is exerted on its end effector. The compliance properties of the proposed flexible manipulator have also been verified in both the horizontal and the vertical directions.

Actuation Redundancy as a Way to Improve the Acceleration Capabilities of 3T and 3T1R Pick-and-Place Parallel Manipulators

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
David Corbel ◽  
Marc Gouttefarde ◽  
Olivier Company ◽  
François Pierrot
Keyword(s):  
Dynamic Model ◽  
Dynamic Capabilities ◽  
Robot Manipulators ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Actuation Redundancy ◽  
High Acceleration ◽  
Pick And Place ◽  
Very High

This paper analyzes the possible contribution of actuation redundancy in obtaining very high acceleration with parallel robot manipulators. This study is based on redundant and nonredundant Delta/Par4-like manipulators, which are frequently used for pick-and-place applications, and addresses the cases of translational manipulators (also called 3T manipulators) and manipulators with Schoenflies motions (also called 3T1R manipulators). A dynamic model, valid for both redundant and nonredundant manipulators, is used to analyze the moving platform’s acceleration capabilities: (i) at zero speed and in any direction and (ii) at zero speed in the “best” direction. The results show that actuation redundancy makes it possible to homogenize dynamic capabilities throughout the workspace and to increase the moving platform’s accelerations. Designs of redundant Delta/Par4-like manipulators capable of high acceleration pick-and-place trajectories are presented for both 3T and 3T1R manipulators.

Dynamic Analysis of a Parallel Pick-and-Place Robot With Flexible Links

2008 ◽  
Author(s):  
Haihong Li ◽  
Zhiyong Yang
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Lithium Ion ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Modeling And Analysis ◽  
Flexible Links ◽  
Pick And Place ◽  
Floating Frame ◽  
Pick And Place Operation

The dynamic modeling and analysis of a 2-DOF translational parallel robot for high-speed pick-and-place operation was presented. Considering the flexibility of all links, the governing equation of motion of a flexible link is formulated in the floating frame of reference using Euler-Lagrange method. A kineto-elasto dynamic model of the system is achieved, ready for modal analysis. Simulation in FEM software showed the similar modes with above computational result in typical location and rotation. The dynamic experiment presented the dominant modes and proved the theoretical analysis and simulation. The Diamond robot used in Lithium-ion battery sorting was taken as an example to demonstrate how to finish above studies. The result shows that the mechanism has good dynamic performance. The work is available for all parallel robots with flexible links.

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.

Accuracy Analysis Considering Clearances and Elastic Deformations in Parallel Manipulators

2011 ◽  
Author(s):  
Jokin Aginaga ◽  
Oscar Altuzarra ◽  
Erik Macho ◽  
Jon Olza
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Linear Analysis ◽  
Accuracy Analysis ◽  
Elastic Deformations ◽  
End Effector ◽  
Planar Mechanism ◽  
General Methodology ◽  
Pick And Place ◽  
Mechanical Components

Clearances at joints and deformability of links produce a loss of accuracy when positioning a mechanism. End-effector pose error depends on the mechanism configuration, the applied external wrenches, the nature and magnitude of clearances and the rigidity of the mechanical components. Clearance magnitudes and elastic deformations are much smaller than other dimensions and consequently they are assumed to be infinitesimal, which leads to a linear analysis. Under this assumption, velocity equations can be utilized instead of position ones, and they can be easily expressed by using screw coordinates. A general methodology for analyzing the pose accuracy of a parallel manipulator is presented, making use of the example of a 5R planar mechanism along a pick-and-place trajectory.

Parallel Manipulators With a Rotation-Symmetric Arm System

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Mats Isaksson ◽  
Torgny Brogårdh ◽  
Saeid Nahavandi
Keyword(s):  
Parallel Manipulators ◽  
High Accuracy ◽  
Parallel Robots ◽  
High Acceleration ◽  
Rotation Symmetric ◽  
The Common

Parallel manipulators with a rotation-symmetric arm system possess all the typical advantages of parallel robots, such as high acceleration and high-accuracy positioning. Contrary to the majority of proposed parallel manipulators, the rotation-symmetric arm system leads to a large workspace in relation to the footprint of the manipulator. This paper focuses on a subclass of these manipulators with additional favorable qualities, including low inertia and high eigenfrequencies. These qualities are achieved using only 5-DOF lower arm links and by mounting all actuators on the nonmoving base column of the manipulator. The common feature of all previously proposed manipulators in this subclass is identified and several novel 3-DOF and 4-DOF members are introduced.

Kinematic and Dynamic Analysis of Flexible-Link Parallel Robots by Means of an ERLS Approach

2012 ◽  
Author(s):  
Renato Vidoni ◽  
Paolo Boscariol ◽  
Alessandro Gasparetto ◽  
Marco Giovagnoni
Keyword(s):  
Dynamic Performance ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Software Implementation ◽  
Flexible Link ◽  
Flexible Links ◽  
Serial Robots ◽  
Parallel Kinematic ◽  
Robotics Concepts ◽  
Points Of View

The use of parallel kinematic structures allows to design light manipulators with higher dynamic performance with respect to serial robots. In this work, the issue of accurately modelling the dynamics of lightweight flexible-link parallel robots has been investigated. The Equivalent Rigid-Link System (ERLS) formulation, useful for describing the dynamic evolution of 3D serial robots with flexible-links, has been extended to Parallel-Kinematic-Machines (PKM) both from the theoretical and from the software implementation points of view. Standard robotics concepts of 3D kinematics are exploited to formulate and solve the ERLS kinematics, thus allowing to easily work with this formulation. A simulator, capable of predicting the deformations due to the elasticity of the links, has been developed and some industrial case-studies have been implemented to validate it. The formulation and the developed simulator will give the opportunity to extensively study the deformations of parallel manipulators, allow to predict the vibrations of the system, and, then, compensate them.

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.

Designing a Translational Parallel Manipulator Based on the 3SS Kinematic Joint

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Erik Macho ◽  
Mónica Urízar ◽  
Víctor Petuya ◽  
Alfonso Hernández
Keyword(s):  
Condition Number ◽  
Parallel Manipulator ◽  
Modular Design ◽  
Parallel Manipulators ◽  
Industrial Applications ◽  
Point Of View ◽  
Pick And Place ◽  
Prismatic Joints ◽  
Singularity Locus ◽  
Kinematic Joint

Abstract Nowadays, translational parallel manipulators are widely used in industrial applications related to pick and place tasks. In this paper, a new architecture of a translational parallel manipulator without floating prismatic joints and without redundant constraints is presented, which leads to a robust design from the manufacturing and maintenance point of view. The frame configuration has been chosen with the aim of achieving the widest and most regular operational workspace completely free of singularities. Besides, the position equations of the proposed design are obtained in a closed form, as well as the singularity locus. It will be shown that the proposed design owns a very simple kinematics so that the related equations can be efficiently implemented in the control of the robot. In addition, the Jacobian condition number assessment shows that a wide part of the operational workspace is well-conditioned, and also the existence of an isotropic configuration will be proved. Finally, a prototype has been built by following a modular design approach.

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