Workspace Analysis and Performance Evaluation of a 6/6 Cable-Suspended Parallel Robot

2013 ◽  
Vol 655-657 ◽  
pp. 1114-1118
Author(s):  
Hui Zhou ◽  
Yi Cao ◽  
Jing Hu Yu ◽  
Gui Lan Chen ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Special Class ◽  
Screw Theory ◽  
Condition Index ◽  
Parallel Robot ◽  
Workspace Analysis ◽  
Global Condition ◽  
Moving Platform ◽  
And Performance ◽  
Velocity Transmission

This paper mainly addressed the workspace analysis and performance evaluation of a special class of the 6/6 cable-suspended parallel robot. Based on the screw theory and the static equilibrium, the Jacobian matrix of the cable -suspended parallel robot is constructed. The workspace volume is characterized as the set of points where the centroid of the moving platform can reach with tensions in all suspension cables for a constant orientation. This paper attempts to tackle some aspects of optimal design of this special class of the 6/6 cable-suspended parallel robot by addressing the variations of the workspace volume and the accuracy of the robot using different geometric configurations, different ratios and orientations of the moving platform. The global condition index is used as a performance index of a robot with respect to the force and velocity transmission over the whole workspace.

Kinematics, Workspace Optimization, and Performance Evaluation of a 3-Leg 6-DOF Robot in RRRS Configuration

2020 ◽  
Author(s):  
Nathan A. Jensen ◽  
Carl A. Nelson
Keyword(s):  
Performance Evaluation ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
And Performance ◽  
Workspace Optimization ◽  
Optimization And Performance

Abstract Underactuated parallel manipulators that achieve 6 DOF via multiple controllable degrees of freedom per leg are often pursued and reported due to their large workspaces. This benefit comes at a cost to the manipulator’s performance, however. Such manipulators must then be evaluated in order to characterize their kinematics in terms of position and motion. This paper establishes a pair of inverse kinematic solutions for a previously proposed and prototyped 3-leg, 6-DOF parallel robot. These solutions are then used to define the robot’s workspace with experimental validation and to optimize the robot’s geometry for maximum workspace volume. The linear components of the Jacobian are then defined, allowing for analysis of the manipulability of the robot. The full Jacobian is also defined, and singularities are examined throughout the workspace of the robot.

On the Design of Cable-Suspended Planar Parallel Robots

2004 ◽  
Vol 127 (5) ◽  
pp. 1021-1028 ◽  
Author(s):  
Abbas Fattah ◽  
Sunil K. Agrawal
Keyword(s):  
Condition Index ◽  
Parallel Robots ◽  
Design Parameters ◽  
Objective Functions ◽  
Analysis Methodology ◽  
Design Variables ◽  
Significant Difference ◽  
Global Condition ◽  
Moving Platform ◽  
Set Of Points

In this paper we present a workspace analysis methodology that can be applied for optimal design of cable-suspended planar parallel robots. The significant difference between regular parallel robots and cable-suspended parallel robots is that the cables in cable-suspended robots can only carry tension forces. The workspace of a planar cable robot is characterized as the set of points where a reference point of moving platform can reach with tensions in all suspension cables. In the design of cable-suspended parallel robots, the suspension points of the cables, size and shape of the moving platform are the design variables. The workspace area and global condition index are used as the objective functions to optimize the design parameters. The global condition index is a measure of isotropicity of the manipulator. The design variables are determined for different numbers of cables using both objective functions at a specified orientation and also at different orientations of moving platform. Experimental results to measure the workspace area demonstrate the effectiveness of this method.

Singularity, isotropy, and velocity transmission evaluation of a three translational degrees-of-freedom parallel robot

Robotica ◽  
2012 ◽  
Vol 31 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Yongjie Zhao
Keyword(s):  
Performance Evaluation ◽  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Parallel Robot ◽  
End Effector ◽  
Transmission Index ◽  
Delta Robot ◽  
Singular Configuration ◽  
Velocity Transmission

SUMMARYPerformance evaluation of a parallel robot is a multicriteria problem. By taking Delta robot as an object of study, this paper presents the kinematic performance evaluation of a three translational degrees-of-freedom parallel robot from the viewpoint of singularity, isotropy, and velocity transmission. It is shown that the determinant of a Jacobian matrix cannot measure the distance from the singular configuration due to the existing inverse kinematic singularity of a Delta robot. The determinants of inverse and direct kinematic Jacobian matrices are adopted for the measurement of distance from the singular configuration based on the theory of numerical linear dependence. The denominator of the Jacobian matrix will be lost in the computation of the condition number when the end-effector is on the centerline of the workspace, so the Delta robot may also be nearly at a singular configuration when the condition number of the Jacobian matrix is equal to 1. The velocity transmission index whose physical meaning is the maximum input angular velocity when the end-effector translates in the unit velocity is presented. The evaluation of singularity, isotropy, and velocity transmission of a Delta robot is investigated by simulation. The velocity transmission index can also be used for the velocity transmission evaluation of a parallel robot with pure rotational degrees-of-freedom based on the principle of similarity. The physical meaning is modified to be the maximum input velocity when the end-effector rotates in the unit angular velocity.

scholarly journals A Cable-Driven Parallel Robot With an Embedded Tilt-Roll Wrist

2019 ◽  
Author(s):  
Saman Lessanibahri ◽  
Philippe Cardou ◽  
Stéphane Caro
Keyword(s):  
Optimum Design ◽  
Parallel Robot ◽  
Visual Surveillance ◽  
Degree Of Freedom ◽  
Large Rotation ◽  
Fixed Frame ◽  
Workspace Analysis ◽  
Dynamic Performances ◽  
Moving Platform ◽  
Tomography Scanning

Abstract This paper addresses the optimum design, configuration and workspace analysis of a Cable-Driven Parallel Robot with an embedded tilt-roll wrist. The manipulator is a hybrid robot consisting in an under-constrained moving-platform accommodating a tilt-roll wrist. The embedded wrist provides large amplitudes of tilt and roll rotations and a large translational workspace obtained by the moving-platform. This manipulator is suitable for tasks requiring large rotation and translation workspaces like tomography scanning, camera-orienting devices and visual surveillance. The moving-platform is an eight-degree-of-freedom articulated mechanism with large translational and rotational workspaces and it is suspended from a fixed frame by six cables. The manipulator employs two bi-actuated cables, i.e., cable loops to transmit the power from motors fixed on the ground to the tilt-roll wrist. Therefore, the manipulator achieves better dynamic performances due to a lower inertia of its moving-platform.

scholarly journals Kinematic analysis of a novel 3-CRU translational parallel mechanism

2015 ◽  
Vol 6 (1) ◽  
pp. 57-64 ◽  
Author(s):  
B. Li ◽  
Y. M. Li ◽  
X. H. Zhao ◽  
W. M. Ge
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Structural Characteristics ◽  
Parallel Mechanisms ◽  
Reachable Workspace ◽  
Potential Applications ◽  
Moving Platform ◽  
And Performance

Abstract. In this paper, a modified 3-DOF (degrees of freedom) translational parallel mechanism (TPM) three-CRU (C, R, and U represent the cylindrical, revolute, and universal joints, respectively) structure is proposed. The architecture of the TPM is comprised of a moving platform attached to a base through three CRU jointed serial linkages. The prismatic motions of the cylindrical joints are considered to be actively actuated. Kinematics and performance of the TPM are studied systematically. Firstly, the structural characteristics of the mechanism are described, and then some comparisons are made with the existing 3-CRU parallel mechanisms. Although these two 3-CRU parallel mechanisms are both composed of the same CRU limbs, the types of freedoms are completely different due to the different arrangements of limbs. The DOFs of this TPM are analyzed by means of screw theory. Secondly, both the inverse and forward displacements are derived in closed form, and then these two problems are calculated directly in explicit form. Thereafter, the Jacobian matrix of the mechanism is derived, the performances of the mechanism are evaluated based on the conditioning index, and the performance of a 3-CRU TPM changing with the actuator layout angle is investigated. Thirdly, the workspace of the mechanism is obtained based on the forward position analysis, and the reachable workspace volume is derived when the actuator layout angle is changed. Finally, some conclusions are given and the potential applications of the mechanism are pointed out.

scholarly journals Diseño cinemático de un robot paralelo 2-PRR

2020 ◽  
Vol 25 (3) ◽  
pp. 372-379
Author(s):  
Sebastián Durango Idárraga ◽  
Mariline C. Delgado Martínez ◽  
César A. Álvarez Vargas ◽  
Rubén D. Flórez Hurtado ◽  
Manuel A. Flórez Ruiz
Keyword(s):  
Condition Index ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Normalization Method ◽  
Dimensional Synthesis ◽  
Singular Configurations ◽  
Highly Sensitive ◽  
Global Condition ◽  
Specific Geometry ◽  
Workspace Design

In civil construction Abstract— This paper presents a dimensional synthesis for a 2-PRR planar parallel robot with a structural plane of symmetry. This robot can achieve the translation of the moving platform without changing the orientation, being useful for applications that require controlled positions with high rigidity. Because the performance of parallel robots is highly sensitive to their geometric parameters, many methodologies to state the dimensional synthesis has been developed. We used the method of Parameter - Finiteness Normalization Method (PFNM) to state the dimensional synthesis using Global Condition Index (GCI) and workspace ( ) design atlases. For the two, GCI and , designed atlases, it is not possible to maximize one of the indexes without diminishing the other one, which represents a design compromise. Also, we remark singular configurations that are coming from specific geometry or limit positions. The complete dimensional synthesis is also presented.

scholarly journals A Cable-Driven Parallel Robot With An Embedded Tilt-Roll Wrist

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Saman Lessanibahri ◽  
Philippe Cardou ◽  
Stéphane Caro
Keyword(s):  
Optimum Design ◽  
Parallel Robot ◽  
Visual Surveillance ◽  
Degree Of Freedom ◽  
Large Rotation ◽  
Fixed Frame ◽  
Workspace Analysis ◽  
Dynamic Performances ◽  
Moving Platform ◽  
Tomography Scanning

Abstract This paper addresses the optimum design, configuration, and workspace analysis of a cable-driven parallel robot (CDPR) with an embedded tilt-roll wrist. The manipulator consists in a tilt-roll wrist mounted on the moving platform of a suspended CDPR. The embedded wrist provides large amplitudes of tilt and roll rotations and a large translational workspace obtained by the CDPR. This manipulator is suitable for tasks requiring large rotation and translation workspaces such as tomography scanning, camera-orienting devices, and visual surveillance. The moving-platform is an eight-degree-of-freedom articulated mechanism with large translational and rotational workspaces, and it is suspended from a fixed frame by six cables. The manipulator employs two bi-actuated cables, i.e., cable-loops to transmit the power from motors fixed on the ground to the tilt-roll wrist. Therefore, the manipulator achieves better dynamic performances due to a lower inertia of its moving-platform.

Position-singularity analysis of a special class of the Stewart parallel mechanisms with two dissimilar semi-symmetrical hexagons

Robotica ◽  
2012 ◽  
Vol 31 (1) ◽  
pp. 123-136 ◽  
Author(s):  
Baokun Li ◽  
Yi Cao ◽  
Qiuju Zhang ◽  
Zhen Huang
Keyword(s):  
Special Class ◽  
Screw Theory ◽  
Singularity Analysis ◽  
Parallel Mechanisms ◽  
Geometric Characteristics ◽  
Characteristic Plane ◽  
The Matrix ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Singularity Locus

SUMMARYIn this paper, for a special class of the Stewart parallel mechanism, whose moving platform and base one are two dissimilar semi-symmetrical hexagons, the position-singularity of the mechanism for a constant-orientation is analyzed systematically. The force Jacobian matrix [J]T is constructed based on the principle of static equilibrium and the screw theory. After expanding the determinant of the simplified matrix [D], whose rank is the same as the rank of the matrix [J]T, a cubic symbolic expression that represents the 3D position-singularity locus of the mechanism for a constant-orientation is derived and graphically represented. Further research shows that the 3D position-singularity surface is extremely complicated, and the geometric characteristics of the position-singularity locus lying in a general oblique plane are very difficult to be identified. However, the position-singularity locus lying in the series of characteristic planes, where the moving platform coincides, are all quadratic curves compromised of infinite many sets of hyperbolas, four pairs of intersecting lines and a parabola. For some special orientations, the quadratic curve can degenerate into two lines or even one line, all of which are parallel to the ridgeline. Two theorems are presented and proved for the first time when the geometric characteristics of the position-singularity curves in the characteristic plane are analyzed. Moreover, the kinematic property of the position-singularity curves is obtained using the Grassmann line geometry and the screw theory. The theoretical results are demonstrated with several numeric examples.

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