Optimal design of a 3-leg 6-DOF parallel manipulator for a specific workspace

Fu, Jianxun; Gao, Feng

doi:10.3901/cjme.2016.0121.011

Cited by 28 publications

(8 citation statements)

References 25 publications

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“…Thus, there exist some researches about the normalization of Jacobian matrices which are partly rotational and translational. Some of them defined their own methods for normalization and some of them divided Jacobian matrix by the degree of the matrix [29][30][31][32].…”

Section: Performance Indexes and Workpacementioning

confidence: 99%

SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace

Eryılmaz

Omurlu

2019

Journal of Robotics

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The determination of kinematic parameters for a parallel robotic system (PRS) is an important and a critical phase to maximize reachable workspace while avoiding singular configurations. Stewart Platform (SP) mechanism is one of the widely known PRS and it is used to demonstrate the proposed technique. In the related literature, GCI (Global Condition Index) and LCI (Local Condition Index) are the commonly used performance indexes which give a measure about the dexterity of a mechanism. In this work, Sequential Quadratic Programming (SQP) method is used to optimize kinematic parameters of a 6dof 3x3 UPU SP in order to reach maximum workspace satisfying small condition numbers. The radius of mobile and base platforms and the lengths of the legs used in the platform are chosen as kinematic parameters to be optimized in a multiobjective optimization problem. Optimization is performed at different stages and the number of optimized kinematic parameters is increased at each level. In conclusion, optimizing selected kinematic parameters at once by using SQP technique presents the best results for the PRS.

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Section: Performance Indexes and Workpacementioning

confidence: 99%

SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace

Eryılmaz

Omurlu

2019

Journal of Robotics

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“…Herrero et al [38] solve the workspace of 2PRU-1PRS parallel manipulator based on the calculation of inverse kinematics and geometrical constraint and singularity constraint; what is more, they pointed out that maximum inscribed ball can be utilized to measure the workspace. Fu and Gao et al [39] obtained the position workspace and orientation workspace of the parallel manipulator with decoupling three branches of six degrees of freedom by using a numerical searching method and chose the maximum inscribed cylinder and sphere envelope as the specified shade in the workspace.…”

Section: Orientation Workpace Analysismentioning

confidence: 99%

Workspace Analysis of a Hybrid Kinematic Machine Tool with High Rotational Applications

Zhang

Fang

et al. 2018

Mathematical Problems in Engineering

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This paper presents a novel parallel manipulator with one translational and two rotational (1T2R) degrees of freedom that can be employed to form a five-degree-of-freedom hybrid kinematic machine tool for large heterogeneous complex structural component machining in aerospace field. Compared with serial or parallel machine, hybrid machine has the merits of high stiffness, high speed, large workspace, and complicated surface processing ability. To increase stiffness, three-degree-of-freedom redundantly actuated and overconstrained 2PRU-PRPS parallel manipulator (P denotes the active prismatic joint) is proposed, which is utilized as the main body of hybrid machine. By resorting to the screw theory, the degree of freedom of the proposed mechanism is briefly addressed including the initial configuration and general configuration and validated by Grübler-Kutzbach (G-K) equation. Next, kinematic inverse solution and parasitic motion of the parallel manipulator are deduced and the transformational relations between the Euler angle and Tilt-Torsion (T-T) angle are identified. Thirdly, the performance evaluation index of orientation workspace is introduced, and the reachable workspace and joint workspace are formulated. Through specific examples, the reachable workspace, task workspace, and joint workspace of the redundant actuation parallel manipulator are depicted. Compared with overstrained 2PRU-PRS parallel manipulator, corresponding analyses illustrate that the proposed parallel manipulator owns much better orientation capability and is very meaningful to the development of the five-axis hybrid machine tool.

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“…Zhao [14] exploited an algebraic algorithm to optimize the length of the legs of a parallel manipulator to get a desired total orientation workspace. Fu [15] proposed a novel 3-leg 6-DOF parallel manipulator whose three translational and three rotational motions are decoupled, and an algorithm of optimal designing is proposed to find the smallest dimensional parameters of the proposed robot for the desired workspace based on analytical solutions of the forward kinematics. Yang [16] gave the size and position of the desired total orientation workspace, and the leg lengths were obtained by the sixdimensional discretization of the workspace based on the numerical method, and then aiming at the linear combination of the physical size and dexterity index, the geometric parameters of the 6-DOF platform were optimized by the genetic algorithm, which is subject to the given leg lengths.…”

Section: Introductionmentioning

confidence: 99%

Multiobjective Optimization of 6‐DOF Parallel Manipulator for Desired Total Orientation Workspace

Qiang

Wang

Ding

et al. 2019

Mathematical Problems in Engineering

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A desired total orientation workspace for a parallel manipulator is usually an essential requirement in a practical application. At present, for the multiobjective optimization method of 6-DOF parallel manipulator for desired total orientation workspace, it is needed to predefine maximal and minimal lengths of the legs to serve as the constraint, and then the numerical method is used to solve the length of the legs and judge whether the solved maximal and minimal leg lengths meet the constraint. Predefining maximal and minimal length of the legs limits of the optimal range, the numerical method has heavy calculation burden and low calculating accuracy. In this paper, a hybrid method for solving the maximal and minimal lengths of the legs of 6-DOF parallel manipulator with desired total orientation workspace is proposed, and the actuator stroke length is calculated according to the maximal and minimal leg lengths. By judging whether the actuator stroke length can be solved to serve as the constraint, without the predefined maximal and minimal leg lengths to serve as the constraint, the optimal range is enlarged. Aiming at the physical size of the parallel manipulator and the proposed desired workspace condition index (DWCI), the optimization of the geometric parameters of the parallel manipulator is conducted based on the multiobjective optimization algorithm (NSGA-II), which is subject to the actuator stroke length. Stewart platform is set as the example; the geometric parameters of the platform whose workspace contains the desired total orientation workspace are optimized and the hybrid method is proved to be more accurate and efficient compared to the traditional numerical method. This method provides the optimization guidance for engineering designers to design the parallel manipulator for desired total orientation workspace.

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Optimal design of a 3-leg 6-DOF parallel manipulator for a specific workspace

Cited by 28 publications

References 25 publications

SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace

SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace

Workspace Analysis of a Hybrid Kinematic Machine Tool with High Rotational Applications

Multiobjective Optimization of 6‐DOF Parallel Manipulator for Desired Total Orientation Workspace

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