Kinematics, Dynamics and Vibration Models for 3RPR Parallel Kinematics Manipulator

2013 ◽  
Author(s):  
Bashar El-Khasawneh ◽  
Anas Alazzam
Keyword(s):  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Inverse Kinematic ◽  
Parallel Kinematics ◽  
Stiffness Modeling ◽  
Noise Rejection ◽  
Parallel Link ◽  
Parallel Kinematic ◽  
Kinematic Mechanisms ◽  
Dynamics And Vibration

Parallel link manipulators are the type of mechanisms that have closed kinematics chains. Some of their advantages over open kinematics chains (called also serial kinematics manipulators) are their high stiffness and accuracy. This paper carries out forward and inverse kinematic and dynamic analysis on a certain type of parallel kinematic mechanisms. This is needed to conduct vibration analysis on the same platform. The type of mechanism is planar 3 RPR manipulator. This entails identifying the modes of the manipulator. A simplified vibration theoretical model is derived. This derivation helps in the optimization of parallel kinematics machine design for improved/optimized dynamic performance. The implications of dynamic stiffness modeling should reflect on better noise rejection, less chatter during machining, and increasing the bandwidth of such mechanisms to admit running at higher speeds.

Comparative Analysis of a Redundant Pentapod Parallel Kinematic Machine

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Arta Alagheband ◽  
Masih Mahmoodi ◽  
James K. Mills ◽  
Beno Benhabib
Keyword(s):  
Comparative Analysis ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Parallel Kinematic Machine ◽  
High Stiffness ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Stiffness Characteristics ◽  
Kinematic Mechanisms ◽  
Platform Tilt

Parallel kinematic mechanisms (PKMs) provide high stiffness and compact structures that are suitable for a large number of applications, including 5-axis milling. This paper presents a new pentapod-based PKM with an additional redundant degree-of-freedom (DOF) capable of reaching platform tilt angles of at least 90 deg over a large workspace. The proposed new PKM has a 6DOF 4 × SPRR + 1 × PSPR architecture. It is compared herein to Metrom® Pentapod as well as to several other pertinent PKMs in terms of workspace and dynamic stiffness. It is shown that the proposed mechanism can yield a tangibly larger workspace volume, when compared to those PKMs, while maintaining its high stiffness characteristics.

The Surface Roughness Effect on the Dynamic Stiffness and Damping Characteristics of the Hydrostatic Thrust Spherical Bearings: Part 5 of 5 — Clearance Type of Bearings

2007 ◽  
Author(s):  
Ahmad W. Yacout
Keyword(s):  
Surface Roughness ◽  
Capillary Tube ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Major Effect ◽  
Design Parameters ◽  
Compressibility Effect ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Fluid Compressibility

This study has theoretically analyzed the surface roughness, centripetal inertia and recess volume fluid compressibility effects on the dynamic behavior of a restrictor compensated hydrostatic thrust spherical clearance type of bearing. The stochastic Reynolds equation, with centripetal inertia effect, and the recess flow continuity equation with recess volume fluid compressibility effect have been derived to take into account the presence of roughness on the bearing surfaces. On the basis of a small perturbations method, the dynamic stiffness and damping coefficients have been evaluated. In addition to the usual bearing design parameters the results for the dynamic stiffness and damping coefficients have been calculated for various frequencies of vibrations or squeeze parameter (frequency parameter) and recess volume fluid compressibility parameter. The study shows that both of the surface roughness and the centripetal inertia have slight effects on the stiffness coefficient and remarkable effects on the damping coefficient while the recess volume fluid compressibility parameter has the major effect on the bearing dynamic characteristics. The cross dynamic stiffness showed the bearing self-aligning property and the ability to oppose whirl movements. The orifice restrictor showed better dynamic performance than that of the capillary tube.

scholarly journals Development of a Hydraulic Parallel Link Force Display -Improvement of Manipulability Using a Disturbance Observer and its Application to a Master-slave System-

2003 ◽  
Vol 15 (4) ◽  
pp. 391-397 ◽  
Author(s):  
Shigeki Kudomi ◽  
◽  
Hironao Yamada ◽  
Takayoshi Muto ◽  
Keyword(s):  
Dynamic Performance ◽  
Load Force ◽  
Slave System ◽  
Disturbance Compensation ◽  
Practical Application ◽  
Hydraulic Cylinders ◽  
Six Dof ◽  
Parallel Link ◽  
Hydraulic Manipulator ◽  
Master Slave System

We previously developed a six-DOF parallel link force display that is actuated by six hydraulic cylinders. The manipulability of the display, however, was insufficient at first, because the dynamic performance of each cylinder was not necessarily the same as that of the others. To overcome this problem, in the present study we have applied disturbance compensation to improve manipulability. To demonstrate a practical application of this force display, we have also constituted a master-slave system in which the display is adopted as the master, and the same type of hydraulic manipulator is adopted as the slave. An operator manipulated the system so that the slave touched a flexible object serving as a load. Our experiments confirmed that the system was controlled with relatively good dynamic performance, and that the operator was able to feel the load force sensitively through the force display.

scholarly journals Modelling, Design and Validation of a Parallel Kinematic Robot for Additive Manufacture Applications

2021 ◽  
pp. 019-029
Author(s):  
Lahoud Marcel ◽  
Melendez Leonardo ◽  
Gil Arturo
Keyword(s):  
Additive Manufacturing ◽  
Open Source Software ◽  
Design Method ◽  
Kinematic Model ◽  
Additive Manufacture ◽  
Parallel Kinematics ◽  
Cartesian Space ◽  
Parallel Kinematic ◽  
Manufacturing Applications ◽  
Design Construction

The additive manufacture is a fabrication process that has taken huge steps in the last decade, even though the first researches and prototypes are around since almost forty years ago. In this article, a design method for a Parallel Kinematics Robot for Additive Manufacturing Applications is proposed. A numerical model is obtained from the kinematics of the robot for which the design, construction and assembly are planned using recycled materials and equipment. The control of the robot is done using open source software, allowing the planning of trajectories in the Cartesian space on a maximum designed cylindrical workspace of 300mm in diameter by 300mm high. At the end of the work the robot was identified, the kinematic model was validated and considerations for future works were given.

scholarly journals Tailoring of Composite Links for Optimal Damped Elasto-Dynamic Performance

1989 ◽  
Author(s):  
D. A. Saravanos ◽  
C. C. Chamis
Keyword(s):  
Optimal Design ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Performance Criteria ◽  
Modal Damping ◽  
Trade Offs ◽  
Design Variables ◽  
Material Systems ◽  
Structural Composite ◽  
Selective Minimization

Abstract A method is developed for the optimal design of composite links based on dynamic performance criteria directly related to structural modal damping and dynamic stiffness. An integrated mechanics theory correlates structural composite damping to the parameters of basic composite material systems, laminate parameters, link shape, and modal deformations. The inclusion of modal properties allows the selective minimization of vibrations associated with specific modes. Ply angles and fiber volumes are tailored to obtain optimal combinations of damping and stiffness. Applications to simple composite links indicate wide margins for trade-offs and illustrate the importance of various design variables to the optimal design.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

Complete kinematic calibration of a 6-RRRPRR parallel kinematic machine based on the optimal measurement configurations

2019 ◽  
Vol 234 (1) ◽  
pp. 121-136 ◽  
Author(s):  
Chunyang Han ◽  
Yang Yu ◽  
Zhenbang Xu ◽  
Xiaoming Wang ◽  
Peng Yu ◽  
...  
Keyword(s):  
Kinematic Model ◽  
Inverse Kinematic ◽  
Error Model ◽  
Kinematic Calibration ◽  
Universal Joint ◽  
Parallel Kinematic Mechanism ◽  
Simulation And Experiment ◽  
Parallel Kinematic ◽  
Kinematic Mechanism ◽  
Selection Of

This paper presents a kinematic calibration of a 6-RRRPRR parallel kinematic mechanism with offset RR-joints that would be applied in space positioning field. In order to ensure highly accurate and highly effective calibration process, the complete error model, which contains offset universal joint errors, is established by differentiating inverse kinematic model. A calibration simulation comparison with non-complete error model shows that offset universal joint errors are crucial to improve the calibration accuracy. Using the error model, an optimal calibration configuration selection algorithm is developed to determine the least number of measurement configurations as well as the optimal selection of these configurations from the feasible configuration set. To verify the effectiveness of kinematic calibration, a simulation and experiment were performed. The results show that the developed approach can effectively improve accuracy of a parallel kinematic mechanism with relatively low number of calibration configurations.

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