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.

scholarly journals Experimental Study of Active Vibration Control of Planar 3-RRR Flexible Parallel Robots Mechanism

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Qinghua Zhang ◽  
Xianmin Zhang ◽  
Junyang Wei
Keyword(s):  
Strain Rate ◽  
Vibration Control ◽  
Active Vibration Control ◽  
Elastic Vibration ◽  
Parallel Robots ◽  
Flexible Link ◽  
Flexible Links ◽  
Rate Feedback ◽  
Active Vibration ◽  
General Motion

An active vibration control experiment of planar 3-RRR flexible parallel robots is implemented in this paper. Considering the direct and inverse piezoelectric effect of PZT material, a general motion equation is established. A strain rate feedback controller is designed based on the established general motion equation. Four control schemes are designed in this experiment: three passive flexible links are controlled at the same time, only passive flexible link 1 is controlled, only passive flexible link 2 is controlled, and only passive flexible link 3 is controlled. The experimental results show that only one flexible link controlled scheme  suppresses elastic vibration and cannot suppress the elastic vibration of the other flexible links, whereas when three passive flexible links are controlled at the same time, they are able to effectively suppress the elastic vibration of all of the flexible links. In general, the experiment verifies that a strain rate feedback controller is able to effectively suppress the elastic vibration of the flexible links of plane 3-RRR flexible parallel robots.

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.

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.

Type Synthesis of 3-DOF PPR-Equivalent Parallel Manipulators Based on Screw Theory and the Concept of Virtual Chain

2005 ◽  
Vol 127 (6) ◽  
pp. 1113-1121 ◽  
Author(s):  
Xianwen Kong ◽  
Clément M. Gosselin
Keyword(s):  
Screw Theory ◽  
Parallel Manipulators ◽  
Type Synthesis ◽  
Motion Patterns ◽  
Kinematic Chains ◽  
Serial Robots ◽  
Application Potential ◽  
Parallel Kinematic ◽  
Moving Platform ◽  
Identical Type

PPR-equivalent parallel manipulators (PMs) are a class of 3-DOF PMs with great application potential. They are indeed the parallel counterparts of the 3-DOF PPR serial robots, in which the moving platform can rotate arbitrarily about an axis undergoing a planar translation. This paper deals with the type synthesis of 3-DOF PPR-equivalent PMs. At first, virtual chains are introduced to represent the motion patterns of 3-DOF motions and relevant results from screw theory are recalled. A method is then proposed for the type synthesis of 3-DOF PPR-equivalent PMs. Using the proposed approach, the type synthesis of 3-DOF PPR-equivalent PMs is performed in three steps. In addition to all the 3-DOF PPR-equivalent parallel kinematic chains and 3-DOF PPR-equivalent PMs proposed in the literature, a number of new 3-DOF PPR-equivalent parallel kinematic chains and 3-DOF PPR-equivalent PMs are identified. It is also found that there are no PPR-equivalent PMs with identical type of legs. The type synthesis of PPR-equivalent PMs is well solved using the proposed approach. The characteristic of the proposed approach is that the type synthesis of PPR-equivalent parallel kinematic chains is reduced to the type synthesis of 3-DOF single-loop kinematic chains and thus easy to perform.

Type Synthesis of 3-DOF PPR Parallel Manipulators Based on Screw Theory and the Concept of Virtual Chain

2004 ◽  
Author(s):  
Xianwen Kong ◽  
Cle´ment M. Gosselin
Keyword(s):  
Screw Theory ◽  
Parallel Manipulators ◽  
Type Synthesis ◽  
Motion Patterns ◽  
Kinematic Chains ◽  
Serial Robots ◽  
Prismatic Joints ◽  
Parallel Kinematic ◽  
Actuated Joints ◽  
Selection Of

PPR-PMs (parallel manipulators) are the parallel counterparts of the 3-DOF PPR serial robots, which are composed of two P (prismatic) joints and one R (revolute) joint. For a PPR-PM, the moving platform can rotate arbitrarily about an axis undergoing a planar translation. This paper deals with the type synthesis of 3-DOF PPR-PMs. At first, virtual chains are introduced to represent the motion patterns of 3-DOF motions and relevant results from screw theory are recalled. A method is then proposed for the type synthesis of 3-DOF PPR-PMs. Using the proposed approach, the type synthesis of 3-DOF PPR-PMs is performed in three steps, namely, the type synthesis of legs for PPR-PKCs (parallel kinematic chains), the type synthesis of PPR-PKCs, and the selection of actuated joints of PPR-PMs. The three steps are dealt with in detail consequently. The characteristics of the proposed approach is that the type synthesis of legs for PPR-PKCs is reduced to the type synthesis of 3-DOF overconstrained single-loop kinematic chains and thus easy to perform. In addition to all the 3-DOF PPR-PKCs and 3-DOF PPR-PMs proposed in the literature, a number of new 3-DOF PPR-PKCs and 3-DOF PPR-PMs are identified. It is also found that there are no PPR-PMs with identical types of legs.

scholarly journals Introduction to the special issue: parallel manipulators.

Robotica ◽  
1997 ◽  
Vol 15 (4) ◽  
pp. 353-353
Author(s):  
François Pierrot
Keyword(s):  
North America ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
Special Issue ◽  
Industrial Areas

It has been a pleasure for me to arrange this Special Issue of Robotica on Parallel Robots which provides 9 papers from authors from Asia, Oceania, North America and Europe; worldwide research on this topic is proof of the growing interest of both the scientific and the industrial areas of parallel mechanisms. I truly believe that the main reason for this enthusiasm is that parallel mechanisms research extends from theoretical mathematics and kinematics to applied robotics, and even beyond, creating new technological challenges.

Variable geometry wing-box: toward a robotic morphing wing.

2021 ◽  
Author(s):  
Amin Moosavian
Keyword(s):  
Degrees Of Freedom ◽  
Minimum Energy ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Optimal Configuration ◽  
Configuration Design ◽  
Variable Geometry ◽  
Static Characteristics ◽  
Actuation Redundancy ◽  
Wing Box

The ability to vary the geometry of a wing to adapt to different flight conditions can significantly improve the performance of an aircraft. However, the realization of any morphing concept will typically be accompanied by major challenges. Specifically, the geometrical constraints that are imposed by the shape of the wing and the magnitude of the air and inertia loads make the usage of conventional mechanisms inefficient for morphing applications. Such restrictions have served as inspirations for the design of a modular morphing concept, referred to as the Variable Geometry Wing-box (VGW). The design for the VGW is based on a novel class of reconfigurable robots referred to as Parallel Robots with Enhanced Stiffness (PRES) which are presented in this dissertation. The underlying feature of these robots is the efficient exploitation of redundancies in parallel manipulators. There have been three categories identified in the literature to classify redundancies in parallel manipulators: 1) actuation redundancy, 2) kinematic redundancy, and 3) sensor redundancy. A fourth category is introduced here, referred to as 4) static redundancy. The latter entails several advantages traditionally associated only with actuation redundancy, most significant of which is enhanced stiffness and static characteristics, without any form of actuation redundancy. Additionally, the PRES uses the available redundancies to 1) control more Degrees of Freedom (DOFs) than there are actuators in the system, that is, under-actuate, and 2) provide multiple degrees of fault tolerance. Although the majority of the presented work has been tailored to accommodate the VGW, it can be applied to any comparable system, where enhanced stiffness or static characteristics may be desired without actuation redundancy. In addition to the kinematic and the kinetostatic analyses of the PRES, which are developed and presented in this dissertation along with several case-studies, an optimal motion control algorithm for minimum energy actuation is proposed. Furthermore, the optimal configuration design for the VGW is studied. The optimal configuration design problem is posed in two parts: 1) the optimal limb configuration, and 2) the optimal topological configuration. The former seeks the optimal design of the kinematic joints and links, while the latter seeks the minimal compliance solution to their placement within the design space. In addition to the static and kinematic criteria required for reconfigurability, practical design considerations such as fail-safe requirements and design for minimal aeroelastic impact have been included as constraints in the optimization process. The effectiveness of the proposed design, analysis, and optimization is demonstrated through simulation and a multi-module reconfigurable prototype.

On Force and Motion Control of Serial-Parallel Robots

1996 ◽  
Author(s):  
Shih-Liang Wang
Keyword(s):  
Control Algorithm ◽  
Virtual Work ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Torque ◽  
Compact Structure ◽  
Serial Robots ◽  
S Matrix ◽  
Serial Robot ◽  
Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

scholarly journals Parallel Robot Translational Performance Evaluation through Direction-Selective Index (DSI)

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
G. Boschetti ◽  
R. Rosa ◽  
A. Trevisani
Keyword(s):  
Performance Evaluation ◽  
Performance Index ◽  
General Framework ◽  
Dynamic Performance ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Performance Indexes ◽  
Definition Of ◽  
Performance Variations

Performance indexes usually provide global evaluations of robot performances mixing their translational and/or rotational capabilities. This paper proposes a definition of performance index, called direction-selective index (DSI), which has been specifically developed for parallel manipulators and can provide uncoupled evaluations of robot translational capabilities along relevant directions. The DSI formulation is first presented within a general framework, highlighting its relationship with traditional manipulability definitions, and then applied to a family of parallel manipulators (4-RUU) of industrial interest. The investigation is both numerical and experimental and allows highlighting the two chief advantages of the proposed DSIs over more conventional manipulability indexes: not only are DSIs more accurate in predicting the workspace regions where manipulators can best perform translational movements along specific directions, but also they allow foreseeing satisfactorily the dynamic performance variations within the workspace, though being purely kinematic indexes. The experiments have been carried out on an instrumented 4-RUU commercial robot.

Gröbner basis and resultant method for the forward displacement of 3-DoF planar parallel manipulators in seven-dimensional kinematic space

Robotica ◽  
2015 ◽  
Vol 34 (11) ◽  
pp. 2610-2628 ◽  
Author(s):  
Davood Naderi ◽  
Mehdi Tale-Masouleh ◽  
Payam Varshovi-Jaghargh
Keyword(s):  
Euclidean Space ◽  
Gröbner Basis ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Dimensional Euclidean Space ◽  
Grobner Basis ◽  
Kinematic Space ◽  
Forward Kinematic Problem ◽  
Forward Kinematic

SUMMARYIn this paper, the forward kinematic analysis of 3-degree-of-freedom planar parallel robots with identical limb structures is presented. The proposed algorithm is based on Study's kinematic mapping (E. Study, “von den Bewegungen und Umlegungen,” Math. Ann.39, 441–565 (1891)), resultant method, and the Gröbner basis in seven-dimensional kinematic space. The obtained solution in seven-dimensional kinematic space of the forward kinematic problem is mapped into three-dimensional Euclidean space. An alternative solution of the forward kinematic problem is obtained using resultant method in three-dimensional Euclidean space, and the result is compared with the obtained mapping result from seven-dimensional kinematic space. Both approaches lead to the same maximum number of solutions: 2, 6, 6, 6, 2, 2, 2, 6, 2, and 2 for the forward kinematic problem of planar parallel robots; 3-RPR, 3-RPR, 3-RRR, 3-RRR, 3-RRP, 3-RPP, 3-RPP, 3-PRR, 3-PRR, and 3-PRP, respectively.

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