Synthesis of 3-[P][S] Parallel Mechanism-Inspired Multimode Dexterous Hands With Parallel Finger Structure

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Xiaodong Jin ◽  
Yuefa Fang ◽  
Dan Zhang ◽  
Haiqiang Zhang
Keyword(s):  
Lie Group ◽  
Inverse Kinematics ◽  
Structural Characteristics ◽  
Synthesis Method ◽  
Parallel Mechanisms ◽  
Key Factors ◽  
End Effector ◽  
Lie Group Theory ◽  
Multimode Operation ◽  
Motion Types

Abstract Dexterous hands are an important end-effector of robots, but their relatively low carrying capacity, small workspace and poor task adaptability are the key factors that restrict their wide application. To overcome these shortcomings of dexterous hands, a novel Lie-group-based synthesis method that extends the 3-[P][S] parallel mechanisms (PMs) to dexterous hands is presented, and a class of three-finger dexterous hands with parallel finger structure is obtained. The multimode operation is proposed by designing a double-slider palm that provides the hands with a large workspace and high task adaptability. The operation types are presented, and the dexterous in-hand manipulations in all modes are analyzed by means of Lie group theory. In addition, the equivalent structural characteristics of pinching objects are classified to elucidate the motion types and the rotational properties of the pinched objects. The inverse kinematics of fingers is presented and is used to identify the input–output relationships. Finally, the workspaces of the fingers are determined according to the result of the inverse kinematics, and the relationships between the size and displacements of the pinched object are presented. The proposed dexterous hands overcome the problems of low carrying capability, small workspace, and weak in-hand manipulation ability that are encountered with the traditional dexterous hands, which are underactuated and are built with a series finger structure, and can be potentially applied to various application domains, such as services, industry, and rescue.

Analyses of Error and Precision of 6-DOF Platform

2012 ◽  
Vol 591-593 ◽  
pp. 2081-2086 ◽  
Author(s):  
Rui Ren ◽  
Chang Chun Ye ◽  
Guo Bin Fan
Keyword(s):  
Inverse Kinematics ◽  
Newton Iteration ◽  
Forward Kinematics ◽  
Parallel Mechanisms ◽  
End Effector ◽  
C Programming Language ◽  
C Programming ◽  
Manufacturing Tolerances ◽  
Parallel Robotics ◽  
Forward Kinematic

A particular subset of 6-DOF parallel mechanisms is known as Stewart platforms (or hexapod). Stewart platform characteristic analyzed in this paper is the effect of small errors within its elements (strut lengths, joint placement) which can be caused by manufacturing tolerances or setting up errors or other even unknown sources to end effector. The biggest kinematics problem is parallel robotics which is the forward kinematics. On the basis of forward kinematic of 6-DOF platform, the algorithm model was built by Newton iteration, several computer programs were written in the MATLAB and Visual C++ programming language. The model is effective and real-time approved by forwards kinematics, inverse kinematics iteration and practical experiment. Analyzing the resource of error, get some related spectra map, top plat position and posture error corresponding every error resource respectively. By researching and comparing the error spectra map, some general results is concluded.

The Dimensional Synthesis of Spatial Cable-Driven Parallel Mechanisms

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
K. Azizian ◽  
P. Cardou
Keyword(s):  
Synthesis Method ◽  
Sufficient Condition ◽  
Nonlinear Program ◽  
Parallel Mechanisms ◽  
Dimensional Synthesis ◽  
End Effector ◽  
A Value ◽  
Null Value ◽  
Objective Value

This paper presents a method for the dimensional synthesis of fully constrained spatial cable-driven parallel mechanisms (CDPMs), namely, the problem of finding a geometry whose wrench-closure workspace (WCW) contains a prescribed workspace. The proposed method is an extension to spatial CDPMs of a synthesis method previously published by the authors for planar CDPMs. The WCW of CDPMs is the set of poses for which any wrench can be produced at the end-effector by non-negative cable tensions. A sufficient condition is introduced in order to verify whether a given six-dimensional box, i.e., a box covering point-positions and orientations, is fully inside the WCW of a given spatial CDPM. Then, a nonlinear program is formulated, whose optima represent CDPMs that can reach any point in a set of boxes prescribed by the designer. The objective value of this nonlinear program indicates how well the WCW of the resulting CDPM covers the prescribed box, a null value indicating that none of the WCW is covered and a value greater or equal to one indicating that the full prescribed workspace is covered.

Type Synthesis of 3-DOF Translational Parallel Manipulators Based on Atlas of DOF Characteristic Matrix

2006 ◽  
Author(s):  
Jingjun Yu ◽  
Jian S. Dai ◽  
Xin-Jun Liu ◽  
Shusheng Bi ◽  
Guanghua Zong
Keyword(s):  
System Theory ◽  
Lie Group ◽  
Synthesis Method ◽  
Parallel Manipulators ◽  
Complete Classification ◽  
Characteristic Matrix ◽  
Type Synthesis ◽  
Lie Group Theory ◽  
Low Degree ◽  
New Type

Low-degree-of-freedom (Low-DOF) parallel manipulators (PMs) have drawn extensive interest, particularly in type synthesis in which two main approaches were established in the reciprocal screw system theory and Lie group theory. This paper aims at proposing a new type synthesis method to complementing the above methods. For this purpose, the concept of the DOF characteristic matrix, originated from displacement subgroup and displacement submanifold, is proposed. A new but general approach based on the atlas of DOF Characteristic Matrix is addressed for both exhaustive classification and type synthesis of low-DOF PMs. Compared to the method based on Lie group, the proposed approach is prone to construct an orthogonal structure and easy to realize the complete classification and exhaustive enumeration of a class of low-DOF PM. In order to verify the effectiveness of the proposed method, type synthesis of Translational PMs (TPMs) particularly in ones with an orthogonal structure is performed, resulting in some novel orthogonal TPMs.

Two classes of reconfigurable parallel mechanisms constructed with multi-diamond kinematotropic chain

2016 ◽  
Vol 230 (18) ◽  
pp. 3319-3330
Author(s):  
Wei Ye ◽  
Yuefa Fang ◽  
Sheng Guo ◽  
Yaqiong Chen
Keyword(s):  
Group Theory ◽  
Lie Group ◽  
Parallel Mechanisms ◽  
Output Link ◽  
Lie Group Theory ◽  
Prismatic Joint ◽  
Operation Modes ◽  
Reconfigurable Mechanisms

This paper presents a novel multi-diamond kinematotropic chain that has various motion branches. The motion allowed by the chain in different branches is identified based on Lie group theory. A planar reconfigurable limb is obtained by adding a prismatic joint to the output link of the multi-diamond kinematotropic chain, leading to the construction of a class of planar reconfigurable parallel mechanisms. With the multi-diamond kinematotropic chain evolving into different motion branches, the planar reconfigurable mechanisms have three distinct configurations in which different operation modes including the 2T1R mode, 2T mode and 1T1R mode can be carried out. The multi-diamond kinematotropic chain is also integrated in the design of spatial reconfigurable limbs, resulting in the construction of a class of spatial reconfigurable parallel mechanisms with ten mobility configurations.

Novel 2R3T and 2R2T parallel mechanisms with high rotational capability

Robotica ◽  
2015 ◽  
Vol 35 (2) ◽  
pp. 401-418 ◽  
Author(s):  
Congzhe Wang ◽  
Yuefa Fang ◽  
Hairong Fang
Keyword(s):  
Machine Tools ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Parallel Mechanisms ◽  
Structural Synthesis ◽  
Lie Group Theory ◽  
Moving Platforms ◽  
Velocity Relationship ◽  
Parallel Machine Tools ◽  
Relationship Of

SUMMARYLarge rotational angles about two axes for parallel mechanisms (PMs) with two rotational and three translational (2R3T) degrees of freedom (DOFs) or two rotational and two translational (2R2T) DOFs are demanded in some industries, such as parallel machine tools and multi-axis 3D printing. To address the problem, this paper focuses on the structural synthesis of new 2R3T and 2R2T PMs with high rotational capability. First, two new moving platforms are proposed based on the concepts of decoupled and configurable design. By means of the proposed platforms and Lie group theory, a series of 2R2T and 2R3T PMs are synthesized. Then the inverse kinematics and velocity relationship of one of the synthesized 2R3T PMs are presented. Finally, the rotational capability of the same 2R3T PM is analyzed. The result shows that by means of actuation redundancy, the studied 2R3T PM indeed possesses the high rotational capability about two axes, even though interferences and singularities are taken into consideration.

Modelling and Simulation of Inverse Kinematics for Planar 3-RRR Parallel Robot Based on SimMechanics

2014 ◽  
Vol 898 ◽  
pp. 510-513 ◽  
Author(s):  
Jin Ran Gao ◽  
Yong Zhao Wang ◽  
Zuo Peng Chen
Keyword(s):  
Inverse Kinematics ◽  
Manufacturing Industry ◽  
Physical Simulation ◽  
Theoretical Foundation ◽  
Controller Design ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Kinematics Simulation

Parallel robots are widely used in the manufacturing industry. In this paper, a planar 3-RRR parallel robot is studied. The inverse kinematics mathematical model is established for this kind of mechanism. Furthermore, a physical simulation model is established by virtue of MATLAB/SimMechanics and a relevant inverse kinematics simulation is implemented at the assumption of known conditions of the end-effector of robot. Through inverse kinematics simulation, the motion rules of driving parts of the planar 3-RRR parallel robot are obtained, and visualization of simulation process is realized in the system. The simulation results show that this method is much more effective and convenient when a certain simulation is implemented for the parallel mechanisms. Meanwhile, it provides a theoretical foundation and a better analytical approach of simulation for the controller design and further analysis of complex multi-linkage mechanisms in the future.

scholarly journals Finite-Horizon Kinetic Energy Optimization of a Redundant Space Manipulator

2021 ◽  
Vol 11 (5) ◽  
pp. 2346
Author(s):  
Alessandro Tringali ◽  
Silvio Cocuzza
Keyword(s):  
Kinetic Energy ◽  
Real Time ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Computational Time ◽  
Redundant Manipulators ◽  
Space Robotics ◽  
Optimal Method ◽  
End Effector ◽  
Global Optimal

The minimization of energy consumption is of the utmost importance in space robotics. For redundant manipulators tracking a desired end-effector trajectory, most of the proposed solutions are based on locally optimal inverse kinematics methods. On the one hand, these methods are suitable for real-time implementation; nevertheless, on the other hand, they often provide solutions quite far from the globally optimal one and, moreover, are prone to singularities. In this paper, a novel inverse kinematics method for redundant manipulators is presented, which overcomes the above mentioned issues and is suitable for real-time implementation. The proposed method is based on the optimization of the kinetic energy integral on a limited subset of future end-effector path points, making the manipulator joints to move in the direction of minimum kinetic energy. The proposed method is tested by simulation of a three degrees of freedom (DOF) planar manipulator in a number of test cases, and its performance is compared to the classical pseudoinverse solution and to a global optimal method. The proposed method outperforms the pseudoinverse-based one and proves to be able to avoid singularities. Furthermore, it provides a solution very close to the global optimal one with a much lower computational time, which is compatible for real-time implementation.

scholarly journals Sol-Gel Synthesis of the Double Perovskite Sr2FeMoO6 by Microwave Technique

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3876
Author(s):  
Jesús Valdés ◽  
Daniel Reséndiz ◽  
Ángeles Cuán ◽  
Rufino Nava ◽  
Bertha Aguilar ◽  
...  
Keyword(s):  
Particle Size ◽  
Hydrothermal Synthesis ◽  
Microwave Radiation ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Synthesis Method ◽  
Double Perovskite ◽  
Synthesis Methods ◽  
X Ray ◽  
Sol Gel Synthesis

The effect of microwave radiation on the hydrothermal synthesis of the double perovskite Sr2FeMoO6 has been studied based on a comparison of the particle size and structural characteristics of products from both methods. A temperature, pressure, and pH condition screening was performed, and the most representative results of these are herein presented and discussed. Radiation of microwaves in the hydrothermal synthesis method led to a decrease in crystallite size, which is an effect from the reaction temperature. The particle size ranged from 378 to 318 nm when pH was 4.5 and pressure was kept under 40 bars. According to X-ray diffraction (XRD) results coupled with the size-strain plot method, the product obtained by both synthesis methods (with and without microwave radiation) have similar crystal purity. The Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques showed that the morphology and the distribution of metal ions are uniform. The Curie temperature obtained by thermogravimetric analysis indicates that, in the presence of microwaves, the value was higher with respect to traditional synthesis from 335 K to 342.5 K. Consequently, microwave radiation enhances the diffusion and nucleation process of ionic precursors during the synthesis, which promotes a uniform heating in the reaction mixture leading to a reduction in the particle size, but keeping good crystallinity of the double perovskite. Precursor phases and the final purity of the Sr2FeMoO6 powder can be controlled via hydrothermal microwave heating on the first stages of the Sol-Gel method.

A Hybrid Self-Stressed Cable-Driven Mechanism

2008 ◽  
Author(s):  
Saeed Behzadipour
Keyword(s):  
Static Loading ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Tensile Force ◽  
Cable System ◽  
End Effector ◽  
Stiffness Analysis ◽  
Cable Length ◽  
Cable Drive ◽  
Forward And Inverse Kinematics

A new hybrid cable-driven manipulator is introduced. The manipulator is composed of a Cartesian mechanism to provide three translational degrees of freedom and a cable system to drive the mechanism. The end-effector is driven by three rotational motors through the cables. The cable drive system in this mechanism is self-stressed meaning that the pre-tension of the cables which keep them taut is provided internally. In other words, no redundant actuator or external force is required to maintain the tensile force in the cables. This simplifies the operation of the mechanism by reducing the number of actuators and also avoids their continuous static loading. It also eliminates the redundant work of the actuators which is usually present in cable-driven mechanisms. Forward and inverse kinematics problems are solved and shown to have explicit solutions. Static and stiffness analysis are also performed. The effects of the cable’s compliance on the stiffness of the mechanism is modeled and presented by a characteristic cable length. The characteristic cable length is calculated and analyzed in representative locations of the workspace.

Equidimensional immersions of locally compact groups

1989 ◽  
Vol 105 (2) ◽  
pp. 253-261 ◽  
Author(s):  
K. H. Hofmann ◽  
T. S. Wu ◽  
J. S. Yang
Keyword(s):  
Exponential Function ◽  
Lie Group ◽  
Compact Groups ◽  
Locally Compact ◽  
Lie Group Theory ◽  
Group A ◽  
Image Position ◽  
Analytic Subgroup ◽  
Algebra Level ◽  
Connected Lie Group

Dense immersions occur frequently in Lie group theory. Suppose that exp: g → G denotes the exponential function of a Lie group and a is a Lie subalgebra of g. Then there is a unique Lie group ALie with exponential function exp:a → ALie and an immersion f:ALie→G whose induced morphism L(j) on the Lie algebra level is the inclusion a → g and which has as image an analytic subgroup A of G. The group Ā is a connected Lie group in which A is normal and dense and the corestrictionis a dense immersion. Unless A is closed, in which case f' is an isomorphism of Lie groups, dim a = dim ALie is strictly smaller than dim h = dim H.

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