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.

Dynamic Performance With Control of a 2DOF Parallel Robot

2012 ◽  
Author(s):  
Gianmarc Coppola ◽  
Dan Zhang ◽  
Kefu Liu ◽  
Zhen Gao
Keyword(s):  
Dynamic Model ◽  
Performance Index ◽  
Parallel Manipulator ◽  
Dynamic Performance ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Performance Study ◽  
Linear Controller ◽  
Reachable Workspace ◽  
And Control

In this work the dynamic performance and control of a 2DOF parallel robot is conducted. The study is partly motivated by large variations in dynamic performance and control within the reachable workspace of many parallel manipulators. The forward dynamic model of the robot is derived in detail. The connection method is directly utilized for this derivation. Subsequently, a dynamic performance study is undertaken. This reveals important information whilst using a forward dynamic model. A performance index is proposed to determine the variability of performance of the parallel manipulator. Then a trajectory-tracking scenario is undertaken using a linear controller. By means of control, the simulations illustrate the validity of the proposed index for parallel manipulators.

The Correlation between Time and Frequency Dynamic Performance of Control System

2014 ◽  
Vol 628 ◽  
pp. 186-189
Author(s):  
Meng Xiong Zeng ◽  
Jin Feng Zhao ◽  
Wen Ouyang
Keyword(s):  
Control System ◽  
Performance Index ◽  
Dynamic Performance ◽  
Frequency Domain Analysis ◽  
Practical Significance ◽  
Order System ◽  
Time Frequency ◽  
Performance Indexes ◽  
Quantitative Performance ◽  
The Stability

The control system performance requirement was divided into three parts. They were the stability, rapidity and accuracy. The time-frequency domain analysis in the requirements of three performance were measured through quantitative performance index. The mutual restriction of time-frequency performance and system characteristic parameters of normal second order was discussed. The correlation of system time-frequency performance index was established. The relationship between time-frequency performance indexes in standard two order system was extended to higher order system. The mutually constraining and time-frequency correlation between each performance index was obtained by analysis and calculation. The work had been done above had practical significance to reflect the system dynamic performance in different analytical domains.

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.

Performance Evaluation for Cable Direct Driven Robot

2014 ◽  
Author(s):  
Giovanni Boschetti ◽  
Alberto Trevisani
Keyword(s):  
Performance Evaluation ◽  
Performance Index ◽  
Parallel Robots ◽  
Performance Evaluations ◽  
Cable Tension ◽  
Cable Robot ◽  
Performance Indexes ◽  
Specific Direction ◽  
Moving Platform ◽  
Cable Forces

The evaluation of cable robot performances cannot neglect the considerable limitations introduced by cable tension bilateral bounds, i.e. the fact that neither negative nor limitless cable forces can be exerted. Therefore, such constraints must be explicitly accounted for and the indexes typically employed for parallel robots cannot be employed straightforwardly. In this work, instead of proposing a new performance index, we introduce an approach to performance evaluations which is based on the computation of the maximum force, along a specific direction, which can be exerted by the cables on the moving platform of a fully actuated or redundant cable robot. Such a computation, once extended to the whole workspace of a robot or, if needed, to any direction, openly and effectively describes the robot performances and can be extremely useful in practice. The application of the method to two fully actuated and fully constrained planar cable robots, together with a comparison with popular performance indexes, gives evidence of the method effectiveness.

Dynamic Performance Evaluation of a Parallel Manipulator with Non Axial Symmetrical Characteristics by Computing the Respective Actuating Joint Capability

2012 ◽  
Vol 2 (4) ◽  
pp. 1-14
Author(s):  
Yongjie Zhao ◽  
Yanling Tian
Keyword(s):  
Performance Evaluation ◽  
Parallel Manipulator ◽  
Dynamic Performance ◽  
Parallel Manipulators ◽  
Joint Torque ◽  
Power Indices ◽  
Joint Power ◽  
Symmetrical Structure ◽  
Capability Evaluation ◽  
Power Capability

Unlike the traditional Gough-Stewart platform with axial symmetrical structure, a parallel manipulator consists of non axial symmetrical structure has non axial symmetrical characteristic in the whole reachable workspace. This paper presents the joint capability evaluation of a parallel manipulator with non axial symmetrical characteristics. A series of velocity, torque and power indices are presented. The torque indices combining the acceleration, velocity, and gravity components of the dynamic model are used to evaluate the respective joint torque capability. The power indices corresponding to the torque indices are also adopted to evaluate the respective joint power capability. The joint capability evaluation of the parallel manipulator is carried out through computational analysis and simulation with the velocity, torque and power indices. It is shown that the respective actuating joint capabilities of the parallel manipulator are not uniform due to the non axial symmetrical structure. Thus the performance evaluation of this type of parallel manipulator must be performed by analyzing the respective joint capability. By means of these indices with obvious physical meanings, it is possible to control the respective joint capability of the parallel manipulator. The indices are general and can be used for the other types of parallel manipulators.

scholarly journals Optimization design using a global and comprehensive performance index and angular constraints in a type of parallel manipulator

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878706 ◽  
Author(s):  
Jiangping Mei ◽  
Xu Zhang ◽  
Jiawei Zang ◽  
Fan Zhang
Keyword(s):  
Performance Index ◽  
Parallel Manipulator ◽  
Optimization Design ◽  
Dynamic Performance ◽  
Mutual Effect ◽  
Parallel Manipulators ◽  
Pressure Angle ◽  
Global Dynamic ◽  
Comprehensive Performance ◽  
Kinematic Optimization

The kinematic optimization of a type of parallel manipulator is addressed. Based on the kinematic analysis, the pressure angles within a limb and among the limbs are introduced, which have definite physical and geometrical meanings. In particular, a type of new pressure angle among the limbs (referred to as the second type of pressure angle among the limbs) is defined and considered to be one of the pressure angle constraints to ensure the kinematic performance. In the kinematic optimization phase, a global and comprehensive performance index, which combines the conditioning number of Jacobian matrix and pressure angles with the volume of workspace, is formulated as an objective function for minimization. One optimal kinematic design example that determines the dimensional parameters is provided to clarify the availability of the proposed approach. The analytical results indicate that good kinematic and dynamic performance can be guaranteed with the suggested design approach. Furthermore, the mutual effect between the dexterity and new pressure angle is analyzed. The effects of the pressure angle constraints on the minimum and maximum conditioning numbers and global dynamic performance indices through the entire workspace are discussed. The proposed research provides a method for the kinematic optimization design of parallel manipulators.

Diagnosis Rule Discovery Based on Causality in the Context of Fault Diagnosis in Rotating Machinery

2014 ◽  
Vol 532 ◽  
pp. 113-117
Author(s):  
Zhou Jin ◽  
Ru Jing Wang ◽  
Jie Zhang
Keyword(s):  
Fault Diagnosis ◽  
General Framework ◽  
Complex Structure ◽  
Rotating Machinery ◽  
Massive Data ◽  
Formal Definition ◽  
Rule Discovery ◽  
Rule Based ◽  
Simple Implementation ◽  
Definition Of

The rotating machineries in a factory usually have the characteristics of complex structure and highly automated logic, which generated a large amounts of monitoring data. It is an infeasible task for uses to deal with the massive data and locate fault timely. In this paper, we explore the causality between symptom and fault in the context of fault diagnosis in rotating machinery. We introduce data mining into fault diagnosis and provide a formal definition of causal diagnosis rule based on statistic test. A general framework for diagnosis rule discovery based on causality is provided and a simple implementation is explored with the purpose of providing some enlightenment to the application of causality discovery in fault diagnosis of rotating machinery.

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