Type Synthesis of 1R1T Remote Center of Motion Mechanisms Based on Pantograph Mechanisms

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Huang Long ◽  
Yang Yang ◽  
Xiao Jingjing ◽  
Su Peng
Keyword(s):  
Fixed Point ◽  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Closed Loop ◽  
Synthesis Method ◽  
Rigid Motion ◽  
Type Synthesis ◽  
Output Link ◽  
Geometric Transformations ◽  
Revolute Joints

The remote center of motion (RCM) mechanism is an important component of a minimally invasive surgery (MIS) robot. The feature of the RCM mechanism is that the output link can rotate around a fixed point and translate along an axis which passes the point; however, there is no revolute joint at the fixed point. The 3R1T RCM mechanism, which meets all the degrees-of-freedom (DOF) requirements of arbitrary MIS tools, can be assembled through many methods. An effective method is combining a planar closed-loop 1R1T RCM mechanism and two revolute joints. In this paper, we present an approach to construct 1R1T RCM mechanisms from pantograph mechanisms. First, pantograph mechanisms are divided into seven classifications according to the geometric transformations they represent. The concept of rigid motion tracking mechanism (RMTM) is proposed by combining two equivalent pantograph mechanisms. Then, a novel type synthesis method for 1R1T RCM mechanisms is discussed in detail, and it shows that a 1R1T RCM mechanism can be constructed by assembling an RMTM and a 1R1T mechanism. By this method, several examples are constructed.

scholarly journals Design and Kinematic Analysis of a Novel 2-DoF Closed-Loop Mechanism for the Actuation of Machining Robots

2021 ◽  
Author(s):  
Angelica Ginnante ◽  
François Leborne ◽  
Stéphane Caro ◽  
Enrico Simetti ◽  
Giuseppe Casalino
Keyword(s):  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parallel Mechanisms ◽  
Serial Manipulators ◽  
Hard Materials ◽  
Serial Robots ◽  
Revolute Joints ◽  
Machining Robot ◽  
Kinematic Models ◽  
Kinematic Performance

Abstract The essential characteristics of machining robots are their stiffness and their accuracy. For machining tasks, serial robots have many advantages such as large workspace to footprint ratio, but they often lack the stiffness required for accurately milling hard materials. One way to increase the stiffness of serial manipulators is to make their joints using closed-loop or parallel mechanisms instead of using classical prismatic and revolute joints. This increases the accuracy of a manipulator without reducing its workspace. This paper introduces an innovative two degrees of freedom closed-loop mechanism and shows how it can be used to build serial robots featuring both high stiffness and large workspace. The design of this mechanism is described through its geometric and kinematic models. Then, the kinematic performance of the mechanism is analyzed, and a serial arrangement of several such mechanisms is proposed to obtain a potential design of a machining robot.

A Rolling 8-Bar Linkage Mechanism

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Yaobin Tian ◽  
Yan-An Yao ◽  
Jieyu Wang
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Rolling Direction ◽  
Linkage Mechanism ◽  
Zero Moment Point ◽  
Revolute Joints ◽  
Straight Line ◽  
Polygonal Region ◽  
Zero Moment

In this paper, a rolling mechanism constructed by a spatial 8-bar linkage is proposed. The eight links are connected with eight revolute joints, forming a single closed-loop with two degrees of freedom (DOF). By kinematic analysis, the mechanism can be deformed into planar parallelogram or spherical 4-bar mechanism (SFM) configuration. Furthermore, this mechanism can be folded onto a plane at its singularity positions. The rolling capability is analyzed based on the zero-moment-point (ZMP) theory. In the first configuration, the mechanism can roll along a straight line. In the second configuration, it can roll along a polygonal region and change its rolling direction. By alternatively choosing one of the two configurations, the mechanism has the capability to roll along any direction on the ground. Finally, a prototype was manufactured and some experiments were carried out to verify the functions of the mechanism.

Automatic Structural Synthesis of the Whole Family of Planar 3-Degrees of Freedom Closed Loop Mechanisms

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Huafeng Ding ◽  
Peng Huang ◽  
Jingfang Liu ◽  
Andrés Kecskeméthy
Keyword(s):  
Degrees Of Freedom ◽  
Closed Loop ◽  
Synthesis Method ◽  
Synthesis Process ◽  
Structural Synthesis ◽  
Planar Mechanisms ◽  
Systematic Method ◽  
Automatic Synthesis ◽  
Heavy Load ◽  
Structure Representation

Conception of the kinematic structures with better performance has been a challenging, yet pivotal issue, since the beginning of the design of mechanisms or robots. This paper proposes a systematic method to synthesize and classify automatically all the valid kinematic structures of planar 3-DOF closed loop mechanisms or robots. First, after the structure representation graphs of planar mechanisms or robots are addressed, the unique representation of both contracted graphs and topological graphs is proposed and used to detect isomorphism in the synthesis process. Then the valid atlas database of the contracted graphs for planar 3-DOF closed loop mechanisms or robots up to 16-link is built. Based on the atlas database, an automatic synthesis method is proposed to synthesize all the kinematic structures of planar 3-DOF closed loop mechanisms or robots, and the complete atlas database with all the valid kinematic structures classified for planar 3-DOF closed loop mechanisms or robots up to 16-link is established. The creative design of 3-DOF heavy-load hydraulic robots is conducted to show the usefulness of the established atlas database.

scholarly journals A simple and visually orientated approach for type synthesis of overconstrained 1T2R parallel mechanisms

Robotica ◽  
2018 ◽  
Vol 37 (7) ◽  
pp. 1161-1173 ◽  
Author(s):  
Tian Huang ◽  
Chenglin Dong ◽  
Haitao Liu ◽  
Tao Sun ◽  
Derek G. Chetwynd
Keyword(s):  
Degrees Of Freedom ◽  
Evaluation Criteria ◽  
Cost Effective ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Output Link ◽  
Component Design ◽  
Hybrid Module ◽  
Visual Approach ◽  
Rational Component

SUMMARYThis paper presents a simple and highly visual approach for the type synthesis of a family of overconstrained parallel mechanisms that have one translational and two rotational movement capabilities. It considers, especially, mechanisms offering the accuracy and dynamic response needed for machining applications. This family features a spatial limb plus a member of a class of planar symmetrical linkages, the latter connected by a revolute joint either to the machine frame at its base link or to the platform at its output link. Criteria for selecting suitable structures from among numerous candidates are proposed by considering the realistic practical requirements for reconfigurability, movement capability, rational component design and so on. It concludes that a few can simultaneously fulfil the proposed criteria, even though a variety of structures have been presented in the literature. Exploitation of the proposed structures and evaluation criteria then leads to a novel five degrees of freedom hybrid module named TriMule. A significant potential advantage of the TriMule over the Tricept arises because all the joints connecting the base link and the machine frame can be integrated into one single, compact part, leading to a lightweight, cost effective and flexible design particularly suitable for configuring various robotized manufacturing cells.

Force Analysis and Mechanical Design of a Novel 3-DOF Parallel Mechanism

2018 ◽  
Author(s):  
Dongsheng Zhang ◽  
Yundou Xu ◽  
Jiantao Yao ◽  
Yulin Zhou ◽  
Yongsheng Zhao
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Synthesis Method ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Constraint Force ◽  
Hybrid Manipulator ◽  
Rotational Degrees Of Freedom ◽  
Motion Characteristics ◽  
Alternative Designs

Parallel mechanisms (PMs) with two rotational degrees-of-freedom (DOF) and one translational DOF (2R1T) have gained much attention in recent years. In this paper, different from type synthesis method, inner properties of PMs (motion characteristics, type of joints and arrangement way of joints) are used to deduce PMs; and two novel 3-DOF PMs are presented using this method. Aiming at 2UPU/SP PM, the constraint force/torque generated on the moving platform (MP) are analysed; here, P, U and S denote prismatic, universal and spherical joints, respectively. The driving force and the constraint force/torque are drawn, which show good distribution of the constraint wrench. After that, a novel 5-DOF hybrid manipulator is constructed on the basis of the 2UPU/SP PM; according to different demands, two alternative designs of the 5-DOF hybrid manipulator are presented. The study in this paper will enhance the research applications of the 2UPU/SP PM.

scholarly journals Type Synthesis of Kinematically Redundant 3T1R Parallel Manipulators

2013 ◽  
Author(s):  
Xianwen Kong ◽  
Damien Chablat ◽  
Stéphane Caro ◽  
Jingjun Yu ◽  
Clément Gosselin
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Singular Configurations ◽  
Revolute Joints ◽  
Solid Foundation ◽  
Moving Platform ◽  
Forward Kinematic ◽  
Open Issues

A kinematically redundant parallel manipulator (PM) is a PM whose degrees-of-freedom (DOF) are greater than the DOF of the moving platform. It has been revealed in the literature that a kinematically redundant PM has fewer Type II kinematic singular configurations (also called forward kinematic singular configurations, static singular configurations or parallel singular configurations) and/or constraint singular configurations than its non-redundant counterparts. However, kinematically redundant PMs have not been fully explored, and the type synthesis of kinematically redundant PMs is one of the open issues. This paper deals with the type synthesis of kinematically redundant 3T1R PMs (also called SCARA PMs or Schoenflies motion generators), in which the moving platform has four DOF with respect to the base. At first, the virtual-chain approach to the type synthesis of kinematically redundant parallel mechanisms is recalled. Using this approach, kinematically redundant 3T1R PMs are constructed using several compositional units with very few mathematical derivations. The type synthesis of 5-DOF 3T1R PMs composed of only revolute joints is then dealt with systematically. This work provides a solid foundation for further research on kinematically redundant 3T1R PMs.

Closed-Loop Tape Springs as Fully Compliant Mechanisms: Preliminary Investigations

2004 ◽  
Author(s):  
Christine Vehar ◽  
Sridhar Kota ◽  
Robert Dennis
Keyword(s):  
Degrees Of Freedom ◽  
Closed Loop ◽  
Compliant Mechanisms ◽  
Variable Stiffness ◽  
Small Radius ◽  
Constant Thickness ◽  
Revolute Joints ◽  
Spring Mechanism ◽  
Actuation Scheme ◽  
Straight Segments

The paper introduces tape springs as elements of fully compliant mechanisms. The localized folds of tape springs serve as compact revolute joints, with a very small radius and large range of motion, and the unfolded straight segments serve as links. By exploiting a tape spring’s ability to function as both links and joints, we present a new method of realizing fully compliant mechanisms with further simplification in their construction. Tape springs, typically found in carpenter tape rules, are thin-walled strips having constant thickness, zero longitudinal curvature, and a constant transverse curvature. The paper presents a closed-loop tape spring mechanism. By representing its folds as idealized revolute joints and its variable length links as sliding joints connecting rigid links, we present a modified Gruebler’s equation to determine its kinematic and idle degrees of freedom. To realize practical utility of tape spring mechanisms, we propose a simple actuation scheme incorporating shape memory alloy (SMA) wire actuators and successfully demonstrate its performance with a proof-of-concept prototype. The paper also presents potential applications for actuated tape spring mechanisms including a large displacement translational mechanism, planar positioning mechanisms, bi-stable, multi-stable, and variable stiffness mechanisms.

scholarly journals Type Synthesis of Variable Compression Ratio Engine Mechanisms

2020 ◽  
Vol 10 (18) ◽  
pp. 6574
Author(s):  
Young Kwang Mo ◽  
Jae Kyung Shim ◽  
Seung Woo Kwak ◽  
Min Seok Jo ◽  
Ho Sung Park
Keyword(s):  
Compression Ratio ◽  
Degrees Of Freedom ◽  
Evaluation Criteria ◽  
Type Synthesis ◽  
Planar Mechanisms ◽  
Variable Compression Ratio ◽  
Revolute Joints ◽  
Variable Compression Ratio Engine ◽  
Independent Loops ◽  
Variable Compression

Type synthesis of two-degrees-of-freedom (DOF) planar mechanisms has been carried out using graph theory to determine the possible kinematic structures of variable compression ratio (VCR) engine mechanisms with two to three independent loops, and has resulted in the structures of 87 mechanisms satisfying search specification. By applying evaluation criteria to the enumerated mechanisms, the kinematic structures of three mechanisms are selected as suitable VCR engine mechanisms and verified by analysis results. In this research, VCR engine mechanisms with revolute joints and only one prismatic joint are enumerated, and the basic method to determine the VCR engine mechanisms with higher pairs is discussed. The procedure used in this research can be utilized to determine the kinematic structures of desired mechanisms and the results can be used as an atlas of two-DOF adjustable slider-crank mechanisms.

scholarly journals Research for a novel class of translational spatial multi-loop coupled mechanisms: Type synthesis and kinematic analysis

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879702 ◽  
Author(s):  
Shuang Zhang ◽  
Jingfang Liu ◽  
Huafeng Ding
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Future Application ◽  
The Novel ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Split Method ◽  
New Synthesis ◽  
The Family

A novel type synthesis method for a class of spatial multi-loop coupled mechanisms with translational degrees of freedom is proposed in the paper. The novel class of spatial multi-loop coupled mechanisms has a stable topology layout which consists of three branches and three coupled chains. The basic idea of the new structural synthesis method lies at replacing the inputs of one mechanism by the outputs of another, thereby combining several mechanisms, where the topology split method for the topological layout and corresponding degree of freedom splitting principle are provided. The synthesis of the target mechanism is transformed into synthesis of corresponding serial and parallel mechanisms thereby, and a class of spatial multi-loop coupled mechanisms is synthesized. To validate the new synthesis method and to present a theoretical basis for future application, kinematic analysis of a single translational mobility (1T) spatial multi-loop coupled mechanism and a symmetrical two translational degrees of freedom (2T) spatial multi-loop coupled mechanism is performed. This article enriches the family of the spatial mechanisms for further instructing the study of spatial multi-loop coupled mechanisms.

Type Synthesis of Parallel Tracking Mechanism With Varied Axes by Modeling Its Finite Motions Algebraically

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Yang Qi ◽  
Tao Sun ◽  
Yimin Song
Keyword(s):  
Geometric Algebra ◽  
Degrees Of Freedom ◽  
Open Loop ◽  
Moving Targets ◽  
Type Synthesis ◽  
Finite Rotation ◽  
Outer Product ◽  
Topological Structures ◽  
Revolute Joints ◽  
Assembly Principles

Parallel tracking mechanism with varied axes has great potential in actuating antenna to track moving targets. Due to varied rotational axes, its finite motions have not been modeled algebraically. This makes its type synthesis remain a great challenge. Considering these issues, this paper proposes a conformal geometric algebra (CGA) based approach to model its finite motions in an algebraic manner and parametrically generate topological structures of available open-loop limbs. Finite motions of rigid body, articulated joints, and open-loop limbs are formulated by outer product of CGA. Then, finite motions of parallel tracking mechanism with varied axes are modeled algebraically by two independent rotations and four dependent motions with the assistance of kinematic analysis. Afterward, available four degrees-of-freedom (4-DoF) open-loop limbs are generated by using revolute joints to realize dependent motions, and available five degrees-of-freedom (5-DoF) open-loop limbs are obtained by adding one finite rotation to the generated open-loop limbs. Finally, assembly principles in terms of minimal number and combinations of available open-loop limbs are defined. Typical topological structures are synthesized and illustrated.

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