Workspace Analysis and the Effect of Geometric Parameters for Parallel Mechanisms of the N-UU Class

Shah, Divya; Metta, Giorgio; Parmiggiani, Alberto

doi:10.1115/detc2018-85258

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…Both the Omniwrist and the Quaternion mechanisms (Figure 6e,f), achieve a full tilt (90°) for all values of azimuth angle φ. However, a peculiar "warping" (asymmetry) behavior is observed in case of the Omniwrist mechanism, as described in the previous work of the authors [30]. (e) OmniWrist (f) Quaternion Figure 6.…”

Section: Orientation Angles With Regard To Joint Coordinatessupporting

confidence: 60%

“…However, for the other three cases, the Cartesian workspace is only a partial hemisphere. Interestingly, the top view of the workspace of the Omniwrist mechanism ( Figure 5e) shows its boundaries are not symmetric with respect to the zero-abscissa and zero-ordinate axes, as reported in [30].…”

Section: Normalized Cartesian Workpacementioning

confidence: 72%

“…Examples of this approach can be found in [16,18,24,29]. A typical characteristic of parallel mechanisms is that their kinematic behavior tends to be more complex, often "non-uniform" (see [30,31]) with respect to their serial counterparts. This complicates both the design and control of this type of mechanisms.…”

Section: Actuator Relocationmentioning

confidence: 99%

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A Comparison of Robot Wrist Implementations for the iCub Humanoid †

Shah

Scalzo

et al. 2019

Robotics

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This article provides a detailed comparative analysis of five orientational, two degrees of freedom (DOF) mechanisms whose envisioned application is the wrist of the iCub humanoid robot. Firstly, the current iCub mk.2 wrist implementation is presented, and the desired design objectives are proposed. Prominent architectures from literature such as the spherical five-bar linkage and spherical six-bar linkage, the OmniWrist-III and the Quaternion joint mechanisms are modeled and analyzed for the said application. Finally, a detailed comparison of their workspace features is presented. The Quaternion joint mechanism emerges as a promising candidate from this study.

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Section: Orientation Angles With Regard To Joint Coordinatessupporting

confidence: 60%

Section: Normalized Cartesian Workpacementioning

confidence: 72%

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A Comparison of Robot Wrist Implementations for the iCub Humanoid †

Shah

Scalzo

et al. 2019

Robotics

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“…In a recent breakthrough, a pioneering approach has emerged to unlock the potential of 2-DOF rotational parallel manipulators (RPMs) within a significantly expanded and singularity-free workspace. Leading works by Sofka et al [13], Dong et al [14], Wu et al [15], Shah et al [16], and Chang et al [17] have championed this concept.…”

Section: Introductionmentioning

confidence: 99%

Kinematic Analysis of a New 3-DOF Parallel Wrist-Gripper Assembly with a Large Singularity-Free Workspace

Ghaedrahmati,

Gosselin

2023

Actuators

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This paper introduces a novel dexterous 3-DOF parallel wrist-gripper assembly with a large singularity-free range of motion. It consists of a zero-torsion 2-DOF parallel wrist and a 1-DOF parallel gripper. The wrist produces a 2-DOF sphere-on-sphere pure rolling motion. This large singularity-free 2-DOF sphere-on-sphere pure rolling motion of the wrist allows for smooth and precise manipulation of objects in various orientations, making it suitable for applications such as assembly, pick-and-place, and inspection tasks. Using a geometrical approach, analytical solutions for the inverse and forward kinematics problems of the wrist and gripper are derived. From the inverse kinematic equations, the Jacobian matrices are derived and it is shown that the whole workspace is free of type I and type II singularities. It is shown that with a proper choice of design variables, a large singularity-free range of motion can be obtained. The absence of singularities in the whole workspace of the wrist-gripper assembly is an important feature that enhances its reliability. Finally, the correctness of the derived equations for the wrist inverse and forward kinematics are verified using MSC Adams. These results confirm the feasibility and effectiveness of the proposed parallel wrist-gripper assembly. Overall, the novel parallel wrist-gripper assembly presented in this paper demonstrates great potential for improving the efficiency and flexibility of robotic manipulators in a variety of industrial and research applications.

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“…PKMs are particularly interesting for medium-size humanoids such as the iCub [5] because of their compact size and good stiffness characteristics. For this purpose, in previous works, we focused on the numerical simulation of N-UU class mechanisms [6] and on their comparison with various closed spherical linkage mechanisms [7].…”

Section: Introductionmentioning

confidence: 99%

An Evolutionary Approach for the Optimal Design of the iCub mk.3 Parallel Wrist

Bsili

Metta

Parmiggiani

2018

2018 IEEE-RAS 18th International Conference on Humanoid Robots (Humanoids)

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The payload-to-weight ratio is one of the most important metrics when designing robotic wrists. A solution to maximize it and to reduce the share of the motive power required to drive the robot's links is to employ parallel kinematic mechanisms (PKMs). Indeed PKMs allow relocating distal masses closer to the robot's base actually increasing the overall payload. On the other hand, PKMs are often characterized by limited ranges of motion (RoM) and nonuniform motion in their workspace. In this article, we considered a class of 2-DOF spherical six-bar mechanisms. We first developed the kinematic model of the system. We then tackled both the workspace limitation and uniformity issues with a numerical optimization approach. Differential evolution (a multi-objective, multivariate, gradientfree optimization method) was applied to the model of the system to explore a large space of parameter combinations. The optimization algorithm allowed obtaining an almost uniform and large RoM (exceeding 50°on both axes). We then proceeded with the detailed design of the joint as we envision integrating it on the future releases of the iCub robot forearmhand assemblies.

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Workspace Analysis and the Effect of Geometric Parameters for Parallel Mechanisms of the N-UU Class

Cited by 4 publications

References 15 publications

A Comparison of Robot Wrist Implementations for the iCub Humanoid †

A Comparison of Robot Wrist Implementations for the iCub Humanoid †

Kinematic Analysis of a New 3-DOF Parallel Wrist-Gripper Assembly with a Large Singularity-Free Workspace

An Evolutionary Approach for the Optimal Design of the iCub mk.3 Parallel Wrist

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