scholarly journals Accuracy Of Positioning And Orientation Of Effector Of Planar Parallel Manipulator 3RRR

2015 ◽  
Vol 9 (3) ◽  
pp. 151-154
Author(s):  
Monika Prucnal-Wiesztort
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Planar System ◽  
Kinematic Chains ◽  
Numerical Example ◽  
Advantages And Disadvantages ◽  
Planar Parallel Manipulator ◽  
Singular Configuration ◽  
Three Degrees Of Freedom

Abstract Parallel manipulator belongs to group of mechanisms with closed kinematic chains. This feature involves both advantages and disadvantages. The study examined the issue of accuracy of a planar system with three degrees of freedom, with revolute pairs, showing the effect of errors of the drives settings on effector positioning deviation. Enclosed is a numerical example for which analyzed the deviation in motion manipulator when going through the singular configuration. Based on the analysis was determined the area around the singular positions for which to obtain the orientation of the assumed accuracy is impossible.

Force transmission and constraint analysis of a 3-SPR parallel manipulator

2017 ◽  
Vol 232 (23) ◽  
pp. 4399-4409 ◽  
Author(s):  
Matteo Russo ◽  
Marco Ceccarelli ◽  
Yukio Takeda
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Single Point ◽  
Open Loop ◽  
Mobile Platform ◽  
Force Transmission ◽  
Singularity Problem ◽  
Kinematic Chains ◽  
Advantages And Disadvantages ◽  
Transmission Index

This paper presents an analysis of a novel 3-SPR parallel manipulator with 3 degrees-of-freedom that is characterized by a mobile platform consisting of a single point where all the three open-loop kinematic chains converge. The constraint singularity problem of the mechanism is solved in closed form by computing the Jacobian of the manipulator. Then, the expression of the transmission index is obtained for the 3-SPR manipulator by using the pressure angle definition. In order to evaluate the influence of secondary parameters, an equivalent 6-SPS mechanism is analyzed and its transmission index is computed in the parameter space. Finally, the proposed manipulator is compared to a standard 3-SPR parallel mechanism to investigate the influence of the mobile platform radius over transmission index and workspace volume. The results are discussed in order to highlight the advantages and disadvantages of the proposed structure of parallel manipulator.

Visual servoing framework using Gaussian process for an aerial parallel manipulator

2018 ◽  
Vol 233 (9) ◽  
pp. 3408-3425
Author(s):  
Sungwook Cho ◽  
David Hyunchul Shim
Keyword(s):  
Gaussian Process ◽  
Parallel Manipulator ◽  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Flight Test ◽  
Control Input ◽  
Body Velocity ◽  
Aerial Vehicle ◽  
Three Degrees Of Freedom ◽  
Traditional Image

This paper proposes a Gaussian process based visual servoing framework for an aerial parallel manipulator. Our aerial parallel manipulator utilizes the on-board eye-in-hand vision sensor system attached on the end-effector of three-degrees-of-freedom parallel manipulator. There are three major advantages: small, light in weight, and linearity with respect to the host vehicle rather than the serial manipulator, but it has a critical drawback that its workspace is too small to perform the mission itself during the hovering. In order to overcome the limited workspace problem and perform the mission more actively, proposed visual servoing framework is proposed to generate relative body velocity commands of the host vehicle by using the interpolated and extrapolated feature path between the initial and desired features to fed into the underactuated aerial parallel manipulator. It can generate not only numerical stable but also feasible control input. Furthermore, it can overcome the weakness of the traditional image-based visual servoing such as singularities, uncertainties, and local minimums during calculating image Jacobian under the large disparity environment between the target and the unmanned aerial vehicle. As a result of the proposed contribution, we show that our contribution is reliable to perform the picking-and-replacement autonomously, and it shows that it can be applied in the large displacement environments throughout the flight test.

scholarly journals A robomech class parallel manipulator with three degrees of freedom

2020 ◽  
Vol 3 (7 (105)) ◽  
pp. 44-56
Author(s):  
Zhumadil Baigunchekov ◽  
Azamat Mustafa ◽  
Tarek Sobh ◽  
Sarosh Patel ◽  
Muratulla Utenov
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Three Degrees Of Freedom

Potential of the 3-UPU Translational Parallel Manipulator

2010 ◽  
Author(s):  
Ahmed Hachem Chebbi ◽  
Vincenzo Parenti-Castelli
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Joint Clearance ◽  
General Frame ◽  
Pure Rotation ◽  
Work Done ◽  
Relevant Work ◽  
Three Degrees Of Freedom

The 3-UPU three degrees of freedom fully parallel manipulator, where U and P are for universal and prismatic pair respectively, is a very well known manipulator that can provide the platform with three degrees of freedom of pure translation, pure rotation or mixed translation and rotation according to the relative directions of the revolute axes. Many studies have been reported in the literature on singularities, workspace and joint clearance influence on the platform accuracy of this manipulator. However, much work has still to be done to reveal all the features this topology can offer to the designer. This paper collects the previous most relevant work done on the 3-UPU parallel manipulator and shows the main results in a coherent general frame. The paper proposes new architectures of the 3-UPU manipulator which offer interesting features to the designer. Finally, based on a number of indexes, a procedure is proposed that allows the designer to select the best architecture of the 3-UPU manipulator for a given task.

Vehicle Shimmy Modeling With Pacejka's Magic Formula and the Delayed Tire Model

2020 ◽  
Vol 15 (3) ◽  
Author(s):  
Tian Mi ◽  
Gabor Stepan ◽  
Denes Takacs ◽  
Nan Chen
Keyword(s):  
Degrees Of Freedom ◽  
Steering System ◽  
Tire Model ◽  
Magic Formula ◽  
Advantages And Disadvantages ◽  
Contact Models ◽  
Three Degrees Of Freedom

Abstract This paper investigates a three-degrees-of-freedom (DoF) shimmy model of vehicle front wheels with steering system and dependent suspension. The contact models of rigid ground and elastic tire are analyzed from the viewpoint of predicting shimmy. Pacejka's magic formula and the delayed tire model are compared by means of stability charts in various parameter domains. Conclusions are obtained regarding the advantages and disadvantages of the use of the delayed tire model.

A Measure for Evaluation of Maximum Acceleration of Redundant and Nonredundant Parallel Manipulators

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Jun Wu ◽  
Binbin Zhang ◽  
Liping Wang
Keyword(s):  
Dynamic Model ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Virtual Work ◽  
Parallel Manipulators ◽  
Maximum Acceleration ◽  
Virtual Work Principle ◽  
Joint Force ◽  
Joint Forces ◽  
Three Degrees Of Freedom

The paper deals with the evaluation of acceleration of redundant and nonredundant parallel manipulators. The dynamic model of three degrees-of-freedom (3DOF) parallel manipulator is derived by using the virtual work principle. Based on the dynamic model, a measure is proposed for the acceleration evaluation of the redundant parallel manipulator and its nonredundant counterpart. The measure is designed on the basis of the maximum acceleration of the mobile platform when one actuated joint force is unit and other actuated joint forces are less than or equal to a unit force. The measure for evaluation of acceleration can be used to evaluate the acceleration of both redundant parallel manipulators and nonredundant parallel manipulators. Furthermore, the acceleration of the 4-PSS-PU parallel manipulator and its nonredundant counterpart are compared.

A Calibration Method for a Three-Degrees-of-Freedom Parallel Manipulator with a Redundant Passive Chain

2012 ◽  
Vol 162 ◽  
pp. 171-178 ◽  
Author(s):  
Takaaki Oiwa ◽  
Harunaho Daido ◽  
Junichi Asama
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Least Squares Method ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Displacement Sensor ◽  
Measurement Experiment ◽  
Measuring Machine ◽  
Measured Length ◽  
Three Degrees Of Freedom

This paper deals with parameter identification for a three-degrees-of-freedom (3-DOF) parallel manipulator, based on measurement redundancy. A redundant passive chain with a displacement sensor connects the moving stage to the machine frame. The passive chain is sequentially placed in three directions at approximately right angles to one another to reliably detect the motion of the stage. Linear encoders measure changes in lengths of the passive chain and the three actuated chains of the manipulator during traveling of the moving stage. Comparison between the measured length and the length calculated from forward kinematics of the 3-DOF manipulator reveals a length error of the passive chain. The least-squares method using a Jacobian matrix corrects 27 kinematic parameters so that the length errors of the passive chain are minimized. The above calculations were accomplished in both numerical simulations and experiments employing a coordinate measuring machine based on the parallel manipulator. Moreover, a length measurement simulation of gauge block measurement and a measurement experiment using the measuring machine were performed to verify the identified parameters.

Direct Kinematic Singularities of 3-3 Stewart-Gough Platforms

2005 ◽  
Vol 219 (4) ◽  
pp. 311-324 ◽  
Author(s):  
C H Liu ◽  
J Chiu
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Polynomial Equation ◽  
Numerical Results ◽  
Polynomial Equations ◽  
Kinematic Singularity ◽  
Cubic Polynomial ◽  
Singular Configuration ◽  
Kinematic Singularities ◽  
Stewart Gough Platform

In this article, a method to locate direct kinematic singularities of a 3-3 Stewart-Gough parallel manipulator (called a Stewart manipulator henceforth) is proposed. The Stewart manipulator is first replaced by an analogous manipulator, the 3PRPS parallel manipulator, and as the first three active joints of this manipulator remain fixed, this manipulator reduces to an asymmetric 3RPS parallel manipulator. With all moving platform's degrees of freedom, except its height, properly specified, there exists at least one height that gives rise to direct kinematic singularity of the asymmetric 3RPS manipulator and this height is a root of a cubic polynomial equation. The procedure to locate direct kinematic singularities thus reduces to solving cubic polynomial equations. Numerical results show that every singular configuration of the asymmetric 3RPS manipulator thus-determined is also a singular configuration of the 3-3 Stewart-Gough platform.

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