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Parallel Manipulators (parallel + manipulator)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

OPTIMAL MECHANISM DESIGN AND DYNAMIC ANALYSIS OF A 3-LEG 6-DOF LINEAR MOTOR BASED PARALLEL MANIPULATOR

ASIAN JOURNAL OF CONTROL, Issue 1 2004
Thong-Shing Hwang
ABSTRACT This paper presents the optimal mechanism design and dynamic analysis of a prototype 3-leg 6-DOF (degree-of-freedom) parallel manipulator. Inverse kinematics, forward kinematics, inverse dynamics and working space characterizing the platform motion are derived. In the presented architecture, the base platform has three linear slideways individually actuated by a synchronous linear servo motor, and each extensible vertical link connecting the upper and base platforms is actuated by an inductive AC servo motor. The linear motors contribute high-speed movements to the upper platform. This kind of architecture using hybrid (linear and AC) motors yields high level performance of motions, especially in the working space. The novel result of maximal working angles is the significant contribution of this architecture. The Taguchi Experimental Method is applied to design the optimal mechanism of the platform system, and the result is used as the actual data to build this system. [source]

Kinematic Calibration and Pose Measurement of a Medical Parallel Manipulator by Optical Position Sensors

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 4 2003
Shaoping Bai
In the applications of parallel manipulators, kinematic calibration is required to eliminate the errors resulting from the manufacturing and assembly of both base and tools. In this paper, a calibration method of base and tool transformation is developed by virtue of optical position sensors. An error model for calibration is constructed using differential geometry method. The pose error is obtained based on pose measurement results of OPTOTRAK 3020, a commercial 3D position measurement system. An iterative least squares procedure is used to identify the error parameters in the base and tool transformations. Simulation and experiment results are presented to demonstrate the effectiveness of the method for transformation matrices calibration. © 2003 Wiley Periodicals, Inc. [source]

CAT4 (Cable Actuated Truss,4 Degrees of Freedom): A Novel 4 DOF Cable Actuated Parallel Manipulator

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2002
Craig Kossowski
The CAT4 (Cable Actuated Truss,4 degrees of freedom) robot is a novel, passively jointed, parallel robot utilizing six control cables for actuation. The architecture has been under development at the Queen's University Robotics Laboratory. The robot utilizes a passive jointed linkage with 18 revolute joints to constrain the end effector motion and provide the desired structural stability, restricting the end effector to 3 translational degrees of freedom (DOF) and 1 DOF for end effector pitch. This central mechanism together with winched cable actuation gives a number of important benefits for applications where the advantages of a parallel robot are required in conjunction with light weight. Six electric motor driven winches control the length of the cable actuators that extend from the top frame to points on the end effector raft and jointed linkage to create a stiff, but lightweight, actuated robot. Simulation work on the robot is presented giving the kinematics, including a computational estimate of the workspace for a specific configuration. Results of computational simulation of the motion of the manipulator and a discussion of the advantages and potential difficulties are also presented. © 2002 Wiley Periodicals, Inc. [source]

Force Transmissibility Performance of Parallel Manipulators

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11 2003
Wen-Tung Chang
In this paper, a new force transmission index called the mean force transmission index (MFTI) is proposed, and the force transmissibility analysis procedure is established for parallel manipulators. The MFTI is an extended definition of the force transmission index (FTI) introduced by the authors previously. It is shown that the FTI is a function of the input velocity ratio (IVR) for a multi-DOF mechanism of the same configuration. To represent the force transmissibility by a definite value, the MFTI is defined as the mean value of the normalized FTIs function over the whole range of the IVR. The force transmissibility analysis of two planar parallel manipulators is illustrated using the MFTI method. The result is compared with that of the Jacobian matrix method and the joint force index (JFI) method. It shows that, especially for symmetric parallel manipulators, an approximate inverse-proportionality relationship exists between the JFI and MFTI, and between the maximum input torque/force and MFTI. It is concluded that the MFTI can be used as a quantitative measure of the force transmissibility performance for parallel manipulators. In the end, a design optimization problem is studied by taking the global force transmission index as the objective function. © 2003 Wiley Periodicals, Inc. [source]

Translational Parallel Manipulators: New Proposals

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2002
Raffaele Di Gregorio
Translational parallel manipulators are parallel manipulators wherein the end-effector performs only spatial translations. This paper presents a new family of translational parallel manipulators. The manipulators of this family are independent constraint manipulators. They have three limbs that are topologically identical and have no rotation singularity. The limbs of these manipulators feature five one-degree-of-freedom kinematic pairs in series. Four joints are revolute pairs and the remaining one, called T-pair, is a kinematic pair that can be manufactured in different ways. In each limb, three adjacent revolute pairs have parallel axes and the remaining revolute pair has an axis that is not parallel to the axes of the other revolute pairs. The mobility analysis of the manipulators of this new family is addressed by taking into account two different choices for the actuated pairs. One of the results of this analysis is that the geometry of a translational parallel manipulator free from singularities can be defined for a particular choice of the actuated pairs. © 2002 Wiley Periodicals, Inc. [source]

Design of a reconfigurable planar parallel manipulator

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2004
R. Fisher
This work presents the design of a reconfigurable planar parallel manipulator (RPPM). The RPPM is designed to act as a testbed manipulator for theories on redundant actuation of parallel manipulators and can reconfigure into three different revolute-jointed mechanism types: a 2-branch 2-DOF (degree-of-freedom) 5-bar mechanism; a 2-branch 3-DOF 6-bar mechanism; and a 3-branch 3-DOF 8-bar mechanism. The design of the RPPM allows for any shoulder or elbow joint to be actuated. In this work, the criteria and constraints of the design are presented. The final design of the RPPM is shown, followed by a discussion of the final design and how it relates to the initial design criteria and constraints. © 2004 Wiley Periodicals, Inc. [source]

Kinematic modeling of mobile robots by transfer method of augmented generalized coordinates

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6 2004
Wheekuk Kim
A kinematic modeling method, which is directly applicable to any type of planar mobile robots, is proposed in this work. Since holonomic constraints have the same differential form as nonholonomic constraints, the instantaneous motion of the mobile robot at current configuration can be modeled as that of a parallel manipulator. A pseudo joint model denoting the interface between the wheel and the ground (i.e., the position of base of the mobile robot) enables the derivation of this equivalent kinematic model. The instantaneous kinematic structures of four different wheels are modeled as multiple pseudo joints. Then, the transfer method of augmented generalized coordinates, which has been popularly employed in modeling of parallel manipulators, is applied to obtain the instantaneous kinematic models of mobile robots. The kinematic models of six different types of planar mobile robots are derived to show the effectiveness of the proposed modeling method. Lastly, for the mobile robot equipped with four conventional wheels, an algorithm estimating a sensed forward solution for the given information of the rotational velocities of the four wheels is discussed. © 2004 Wiley Periodicals, Inc. [source]

Designing and optimization of parameters of delta-4 parallel manipulator for a given workspace

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 9 2003
A. Kosinska
In the paper, the algorithm of designing some geometrical parameters of a Delta parallel manipulator has been described. The manipulator is to work in a specified workspace, which is given as a set of points. The first step of the algorithm seeks the possible solutions, and because there are an infinite number of them, the objective of the second step is to limit the number by an optimization. Owing to this, it is possible to find parameters of the manipulator, whose workspace contains the specified points. © 2003 Wiley Periodicals, Inc. [source]

Algebraic solution to forward kinematics of a 3-DOF spherical parallel manipulator

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2001
Ping Ji
A three degree-of-freedom (3-DOF) spherical parallel manipulator consists of two tetrahedrons (pyramids). The base tetrahedron is fixed while the moving tetrahedron is rotating at the joint apex of the two tetrahedrons. This article studies the forward kinematics to a special 3-DOF spherical parallel manipulator, where the three apical angles of the moving tetrahedron are equal to their counterparts in the base tetrahedron, respectively. The final result of the forward kinematics to this parallel manipulator is a univariate quartic polynomial equation, which has a direct algebraic solution. In addition, a special right-angle case of the manipulator is investigated and its forward kinematics can be obtained directly. © 2001 John Wiley & Sons, Inc. [source]

OPTIMAL MECHANISM DESIGN AND DYNAMIC ANALYSIS OF A 3-LEG 6-DOF LINEAR MOTOR BASED PARALLEL MANIPULATOR

A numerical method for the determination of dextrous workspaces of Gough,Stewart platforms

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2001
L. J. du Plessis
Abstract An optimization approach to the computation of the boundaries of different dextrous workspaces of parallel manipulators is presented. A specific dextrous workspace is the region in space in which, at each position of the working point, a manipulator can control the orientation of its upper working platform through a specified range of orientation angles. Here the dextrous workspace is determined from the intersection of suitably chosen fixed orientation workspaces, which are found by application of a constrained optimization algorithm. The procedure is simple and has the considerable advantage that it may easily be automated. The method is illustrated by its application to both a planar and spatial Gough,Stewart platform. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Type synthesis of 5-DOF parallel manipulators based on screw theory

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005
Xianwen Kong
With the introduction of virtual chains to represent the motion patterns of 5-DOF motions, a classification of 5-DOF PMs (parallel manipulators) is proposed at first. A general method for the type synthesis of 5-DOF PMs is then proposed based on screw theory and using the concept of virtual chains. The type synthesis of US-equivalent PMs is presented in detail to show the application of the proposed approach. US-equivalent PMs are the parallel counterparts of the 5-DOF US serial manipulators. For a US-equivalent PM, the moving platform can rotate arbitrarily about a point moving along a spherical surface. The type synthesis of legs for US-equivalent PKCs (parallel kinematic chains), the type synthesis of US-equivalent PKCs, as well as the selection of actuated joints of US-equivalent PMs are dealt with in sequence. US-equivalent PKCs with and without inactive joints are synthesized. Several US-equivalent PMs as well as other classes of 5-DOF PMs with identical type of legs are obtained. © 2005 Wiley Periodicals, Inc. [source]

The optimum design of 6-DOF isotropic parallel manipulators

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6 2005
K. Y. Tsai
How to obtain 6-DOF parallel manipulators with optimum global isotropy is investigated in this paper. A systematic method is first presented to get isotropic parallel designs. A measure for spatial isotropy is then proposed to evaluate and compare the global isotropy of obtained manipulators. Efficient methods to find the minimum and maximum singular values of matrices are developed to facilitate the evaluation process. © 2005 Wiley Periodicals, Inc. [source]

Design of a reconfigurable planar parallel manipulator

Kinematic modeling of mobile robots by transfer method of augmented generalized coordinates

Force Transmissibility Performance of Parallel Manipulators

Kinematic Calibration and Pose Measurement of a Medical Parallel Manipulator by Optical Position Sensors

Translational Parallel Manipulators: New Proposals

The constant-Jacobian method for kinematics of a three-DOF planar micro-motion stage

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 2 2002
W. J. Zhang
This paper concerns the development of a class of devices that generate end-effector motion in the range of less than 100 ,m and with sub-nanometer resolution; in particular, a parallel manipulator configuration that generates a planar x - y -, motion is considered. The parallel manipulator is implemented as a compliant mechanism. A problem with parallel manipulators is that the forward kinematics is usually too complex, which can hinder the implementation of advanced control algorithms. The contribution of this paper is that a simple method, called the constant-Jacobian (CJ) method, is developed based on the pseudo-rigid body (PRB) approach to compliant mechanisms. The experiment validates the CJ method. © 2002 John Wiley & Sons, Inc. [source]

The synthesis of planar parallel manipulators with prismatic joints for an optimal, singularity-free workspace

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2002
Marise Gallant
The synthesis of three-degree-of-freedom planar parallel manipulators is performed using a genetic algorithm. The architecture of a manipulator and its position and orientation with respect to a prescribed workspace are determined. The architectural parameters are optimized so that the manipulator's constant-orientation workspace is as close as possible to a prescribed workspace. The manipulator's workspace is discretized and its dexterity is computed as a global property of the manipulator. An analytical expression of the singularity loci (local null dexterity) can be obtained from the Jacobian matrix determinant, and its intersection with the manipulator's workspace may be verified and avoided. Results are shown for different conditions. First, the manipulators' workspaces are optimized for a prescribed workspace, without considering whether the singularity loci intersect it or not. Then the same type of optimization is performed, taking intersections with the singularity loci into account. In the following results, the optimization of the manipulator's dexterity is also included in an objective function, along with the workspace optimization and the avoidance of singularity loci. Results show that the end-effector's location has a significant effect on the manipulator's dexterity. © 2002 John Wiley & Sons, Inc. [source]

Generation and forward displacement analysis of two new classes of analytic 6-SPS parallel manipulators

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6 2001
Xianwen Kong
Analytic manipulators are manipulators with a characteristic polynomial of fourth degree or lower. Using the component approach to generate analytic 6-SPS parallel manipulators (PMs), the generation process is reduced to the generation of analytic components for 6-SPS PMs. Two new classes of analytic components for 6-SPS PMs are generated at first. Then, two new classes, IX and X, of analytic 6-SPS PMs are generated. The forward displacement analysis (FDA) of the new analytic 6-SPS PMs is also performed. The FDA of the 6-SPS PMs of class IX is reduced to the solution of one univariate cubic equation and two univariate quadratic equations, in sequence, while that of the 6-SPS PMs of class X is reduced to the solution of three univariate quadratic equations in sequence. Both of the new analytic 6-SPS PMs have at most eight assembly modes. © 2001 John Wiley & Sons, Inc. [source]