Design and kinematic analysis of a 3-RRR spherical parallel manipulator reconfigured with four–bar linkages

Gao, Wu; Bai, Shaoping

doi:10.1016/j.rcim.2018.08.006

Cited by 45 publications

(21 citation statements)

References 28 publications

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“…It is worth noting that the valid singular boundaries (discussed in Sect. 4.2) of the SPM are just part of all the singular boundaries, where the SPM may momentarily lose control and has zero mechanical advantage (Gosselin and Angeles, 1990;Yan and Wu, 1989;Hunt, 1978). The valid singular boundaries are the gather of dead center positions.…”

Section: Discriminants Of Two Spherical Five-bar Loop Equationsmentioning

confidence: 99%

“…Singularities are the core of the full rotatability problem, which represent the singular configurations of the manipulator. At these configurations, the manipulator may lose control momentarily and has zero mechanical advantage (Gosselin and Angeles, 1990;Yan and Wu, 1989;Hunt, 1978). Since singularities are commonly harmful and even damage the manipulator, it is necessary to identify all singularities of the spherical parallel manipulator (SPM) during the design stage.…”

Section: Introductionmentioning

confidence: 99%

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Singularity and branch identification of a 2 degree-of-freedom (DOF) seven-bar spherical parallel manipulator

et al. 2020

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Abstract. Spherical parallel manipulators (SPMs) have a great potential for industrial applications of robot wrists, camera-orientating devices, and even sensors because of their special structure. However, increasing with the number of links, the kinematics analysis of the complex SPMs is formidable. The main contribution of this paper is to present a kind of 2 degree-of-freedom (DOF) seven-bar SPM containing two five-bar spherical loops, which has the advantages of high reaction speed, accuracy rating, and rigidity. And based on the unusual actuated choices and symmetrical loop structure, an approach is provided to identify singularities and branches of this kind of 2 DOF seven-bar SPM according to three following steps. Firstly, loop equations of the two five-bar spherical loops, which include all the kinematic characteristics of this SPM, are established with joint rotation and side rotation. Secondly, branch graphs are obtained by Maple based on the discriminants of loop equations and the concept of joint rotation space (JRS). Then, singularities are directly determined by the singular boundaries of the branch graphs, and branches are easily identified by the overlapping areas of JRS of two five-bar spherical loops. Finally, this paper distinguishes two types of branches of this SPM according to whether branch points exist to decouple the kinematics, which can be used for different performance applications. The proposed method is visual and offers geometric insights into understanding the formation of mobility using branch graphs. At the end of this paper, two examples are employed to illustrate the proposed method.

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Section: Discriminants Of Two Spherical Five-bar Loop Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Singularity and branch identification of a 2 degree-of-freedom (DOF) seven-bar spherical parallel manipulator

et al. 2020

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“…A 3-RRR planar parallel manipulator (PPM) is a type of manipulator with only three degrees of freedom, in which the symbol 3-RRR expresses three branched chains and includes three revolute (R) pairs in each branched chain, which has the advantages of a simple structure, small additional inertia of the driving motor, large stiffness, large workspace, and small cumulative error. It has been widely used in the fields of plane complex curve creation [1], micronano-precision positioning, measurement, and manufacturing [2,3], pick and place operation robots [4,5], modular, detachable, and reconfigurable robots [6], tactile perception [7,8], and additive manufacturing equipment [9,10].…”

Section: Introductionmentioning

confidence: 99%

IBOA‐Based Optimization of Cross‐Sectional Dimension of Rods for a 3‐RRR PPM to Minimize Energy Consumption

et al. 2021

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For obtaining optimal cross-sectional dimensions of rods for a 3-RRR planar parallel manipulator (PPM) to minimize energy consumption, the inverse dynamics of the manipulator is modeled based on the Newton–Euler method, after which the coefficient matrix of the inverse dynamics equation is decomposed based on matrix theory. Hence, the objective function, that is, the logical relationship between the energy consumption of the manipulator and the cross-sectional dimension of each rod, is established. However, in solving the multidimensional constrained single-object optimization problem, there are difficulties such as the penalty function’s sensitivity to the penalty factors if the problem is transformed into the one of unconstrained multiobjective optimization. Therefore, to properly handle the constraints, an improved butterfly optimization algorithm (IBOA) is presented to ensure that the new iterated point always falls into the feasible region according to the butterfly optimization algorithm (BOA). Finally, the comparisons among the IBOA, particle swarm optimization (PSO), and BOA and further experiments of the physical prototype are implemented to validate the effectiveness of the proposed theoretical model and numerical algorithm. Results indicate that the proposed IBOA is more suitable for solving the constrained single-object optimization problem with better convergence speed and accuracy.

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“…Spherical motion, which is probably the most important type of motion after rotary motion, is a multi-DOF rigid body motion along a spherical surface with a permanent center of rotation. Currently, multi-DOF spherical motions are commonly realized by connecting at least two or three actuators in serial or parallel mechanisms; such a configuration results in transmission systems that are quite complex and bulky [1]- [5], which affects the dynamic performance and servo-tracking accuracy. To overcome these drawbacks, this paper presents a novel 2-DOF ball-joint-like hydraulic spherical motion mechanism (SMM).…”

Section: Introductionmentioning

confidence: 99%

Design, Analysis, and Test of a Novel 2-DOF Spherical Motion Mechanism

Bian

Wang

2020

IEEE Access

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A novel two degree-of-freedom (DOF) ball-joint-like hydraulic spherical motion mechanism (SMM) for use in robotic applications is proposed to achieve smooth spherical motion in all directions. Unlike traditional systems that use serial or parallel mechanisms for generating multi-DOF rotations, the proposed SMM is capable of producing continuous 2-DOF rotational motions in a single joint without intermediate transmission mechanisms. The proposed SMM has a compact structure, low inertia, and high stiffness. First, the architecture and operating principle of the proposed SMM is introduced. Then, the kinematic model is established using Euler transformation, following which factors (such as workspace and dexterity) that have an impact on motion performance are evaluated. As the foundation of dynamics analysis and controller design, the Lagrange's equations of the second kind are used to establish the dynamic model. To achieve high tracking accuracy, the radial basis function neural network-based sliding mode controller is applied to the mechanism. The simulation results indicate that the designed controller not only improves trajectory tracking capability but also enhances robustness against external disturbance and system uncertainty. Finally, experiments are performed on a prototype SMM to validate the performance of the proposed SMM and evaluate the control method. INDEX TERMS Spherical motion mechanism, kinematic modeling, motion performance, dynamic modeling, radial basis function neural network-based sliding mode control.

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Design and kinematic analysis of a 3-RRR spherical parallel manipulator reconfigured with four–bar linkages

Cited by 45 publications

References 28 publications

Singularity and branch identification of a 2 degree-of-freedom (DOF) seven-bar spherical parallel manipulator

Singularity and branch identification of a 2 degree-of-freedom (DOF) seven-bar spherical parallel manipulator

IBOA‐Based Optimization of Cross‐Sectional Dimension of Rods for a 3‐RRR PPM to Minimize Energy Consumption

Design, Analysis, and Test of a Novel 2-DOF Spherical Motion Mechanism

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