Kinematic Analysis and Design of a Novel Shoulder Exoskeleton Using a Double Parallelogram Linkage

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Simon Christensen ◽  
Shaoping Bai
Keyword(s):  
Shoulder Joint ◽  
Degrees Of Freedom ◽  
Large Range ◽  
Upper Body ◽  
Element Analysis ◽  
Analysis And Design ◽  
Revolute Joints ◽  
Current State ◽  
Spherical Mechanism ◽  
Three Degrees Of Freedom

The design of an innovative spherical mechanism with three degrees-of-freedom (DOFs) for a shoulder joint exoskeleton is presented in this paper. The spherical mechanism is designed with a double parallelogram linkage (DPL), which connects two revolute joints to implement the motion as a spherical joint, while maintaining the remote center (RC) of rotation. The design has several new features compared to the current state-of-the-art: (1) a relative large range of motion (RoM) free of singularity, (2) high overall stiffness, (3) lightweight, and (4) compact, which make it suitable for assistive exoskeletons. In this paper, the kinematics and singularities are analyzed for the spherical mechanism and DPL. Dimensional analysis is carried out to find the design with maximum RoM. The new shoulder joint is finally designed, constructed, and integrated in a four degree-of-freedom wearable upper-body exoskeleton. A finite element analysis (FEA) study is used to assess the structural stiffness of the proposed design in comparison to the conventional 3R mechanism.

Finite Element Analysis of 2-D Structures by New Strain Based Triangular Element

2018 ◽  
Vol 35 (3) ◽  
pp. 305-313 ◽  
Author(s):  
C. Rebiai
Keyword(s):  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Time Integration ◽  
Triangular Element ◽  
Membrane Element ◽  
Lumped Mass ◽  
Element Analysis ◽  
Benchmark Tests ◽  
Three Degrees Of Freedom

ABSTRACTIn this investigation, a new simple triangular strain based membrane element with drilling rotation for 2-D structures analysis is proposed. This new numerical model can be used for linear and dynamic analysis. The triangular element is named SBTE and it has three nodes with three degrees of freedom at each node. The displacements field of this element is based on the assumed functions for the various strains satisfying the compatibility equations. This developed element passed both patch and benchmark tests in the case of bending and shear problems. For the dynamic analysis, lumped mass with implicit/explicit time integration are employed. The obtained numerical results using the developed element converge toward the analytical and numerical solutions in both analyses.

Dynamic Finite Element Analysis of a Highly Parallel Robotic Surface

2011 ◽  
Author(s):  
Chris Salisbury
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Element Analysis ◽  
Revolute Joints ◽  
Stiffness Matrices ◽  
Joint Forces ◽  
Ricatti Equation ◽  
Optimal Dynamic

A novel three-dimensional robotic surface is devised using triangular modules connected by revolute joints that mimic the constraints of a spherical joint at each triangle intersection. The finite element method (FEM) is applied to the dynamic loading of this device using three dimensional (6 degrees of freedom) beam elements to not only calculate the cartesian displacement and force, but also the angular displacement and torque at each joint. In this way, the traditional methods of finding joint forces and torques are completely bypassed. An effiecient algorithm is developed to linearly combine local mass and stiffness matrices into a full structural stiffness matrix for the easy application of loads. An analysis of optimal dynamic joint forces is carried out in Simulink® with the use of an algebraic Ricatti equation.

scholarly journals Load–Displacement Characterization in Three Degrees-of-Freedom for General Lamina Emergent Torsion Arrays

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Nathan A. Pehrson ◽  
Pietro Bilancia ◽  
Spencer Magleby ◽  
Larry Howell
Keyword(s):  
Degrees Of Freedom ◽  
Design Space ◽  
Element Analysis ◽  
Array Design ◽  
Elastic Load ◽  
In Series ◽  
Load Displacement ◽  
Stiffness Characteristics ◽  
Tunable Stiffness ◽  
Three Degrees Of Freedom

Abstract Lamina emergent torsion (LET) joints for use in origami-based applications enables folding of panels. Placing LET joints in series and parallel (formulating LET arrays) opens the design space to provide for tunable stiffness characteristics in other directions while maintaining the ability to fold. Analytical equations characterizing the elastic load–displacement for general serial–parallel formulations of LET arrays for three degrees-of-freedom are presented: rotation about the desired axis, in-plane rotation, and extension/compression. These equations enable the design of LET arrays for a variety of applications, including origami-based mechanisms. These general equations are verified using finite element analysis, and to show variability of the LET array design space, several verification plots over a range of parameters are provided.

scholarly journals Design and analysis of a 3-DOF planar micromanipulation stage with large rotational displacement for micromanipulation system

2017 ◽  
Vol 8 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Bingxiao Ding ◽  
Yangmin Li ◽  
Xiao Xiao ◽  
Yirui Tang ◽  
Bin Li
Keyword(s):  
Nanoimprint Lithography ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Rotational Displacement ◽  
Revolute Joints ◽  
Kinematic Models ◽  
Lever Mechanism ◽  
Three Degrees Of Freedom

Abstract. Flexure-based mechanisms have been widely used for scanning tunneling microscopy, nanoimprint lithography, fast servo tool system and micro/nano manipulation. In this paper, a novel planar micromanipulation stage with large rotational displacement is proposed. The designed monolithic manipulator has three degrees of freedom (DOF), i.e. two translations along the X and Y axes and one rotation around Z axis. In order to get a large workspace, the lever mechanism is adopted to magnify the stroke of the piezoelectric actuators and also the leaf beam flexure is utilized due to its large rotational scope. Different from conventional pre-tightening mechanism, a modified pre-tightening mechanism, which is less harmful to the stacked actuators, is proposed in this paper. Taking the circular flexure hinges and leaf beam flexures hinges as revolute joints, the forward kinematics and inverse kinematics models of this stage are derived. The workspace of the micromanipulator is finally obtained, which is based on the derived kinematic models.

Reconfigurable Mechanisms From the Intersection of Surfaces

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
P. C. López-Custodio ◽  
J. M. Rico ◽  
J. J. Cervantes-Sánchez ◽  
G. I. Pérez-Soto
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Chain ◽  
Mobility Analysis ◽  
Revolute Joint ◽  
Revolute Joints ◽  
Reconfigurable Mechanisms ◽  
Three Degrees Of Freedom

The method of intersection of surfaces generated by kinematic dyads is applied to obtain mechanisms that are able to shift from one mode of motion to another. Then a mobility analysis shows that the singularities of the generated surfaces can be used to obtain mechanisms which can change their number of degrees-of-freedom depending on its configuration. The generator dyads are connected as usually done by a spherical pair. However, in the cases shown in this contribution the three-degrees-of-freedom of the spherical pair are not all necessary to keep the kinematic chain closed and movable, and the spherical pair can be substituted by either a pair of intersecting revolute joints or a single revolute joint. This substitution can be obtained by means of two methods presented in this contribution.

Quantification of Upper-Body Synergies: A Case Comparison for Stroke and Non-Stroke Victims

2016 ◽  
Author(s):  
Omid Heidari ◽  
John O. Roylance ◽  
Alba Perez-Gracia ◽  
Eydie Kendall
Keyword(s):  
Principal Component Analysis ◽  
Degrees Of Freedom ◽  
Principal Component ◽  
Component Analysis ◽  
Joint Space ◽  
Upper Body ◽  
Dimensional Synthesis ◽  
Revolute Joints ◽  
Case Comparison ◽  
The Individual

Motion synergies are principal components of the movement, obtained as combinations of joint degrees of freedom, that account for common postures of the human body. These synergies are usually obtained by capturing the motion of the human joints and reducing the dimensionality of the joint space with techniques such as principal component analysis. In this work, an experimental procedure to investigate the synergies of the upper body is developed and the results of the pilot study are shown. The upper-limb kinematics includes the joint complexes of the hand, wrist, forearm, elbow, and shoulder. The different kinematic models in the literature have been reviewed, and a serial chain is considered from the upper arm. A three degree of freedom (3-DOF) linkage containing two revolute joints and one prismatic joint has been chosen to simulate the shoulder motion. A spherical joint represents the Glenohumeral (GH) joint; the elbow and ulna-radius rotations are represented by two revolute joints and the wrist is modeled with two revolute joints. The hand has a tree structure and branches into the individual phalanges, with a 2-dof MCP joint and single R joints for the rest of the phalangeal joints. The data are collected using motion capture and the joint angles are calculated using a combination of dimensional synthesis and inverse kinematics. Principal component analysis can be used to extract the synergies for a set of previously-selected motions. The motions are performed by healthy subjects and subjects who have suffered stroke, in order to see the changes in the motion primitives. It is expected that this study will help quantify and classify some of the loss of motion due to stroke.

FEM Based Numerical Simulation of Delta Parallel Mechanism

2013 ◽  
Vol 690-693 ◽  
pp. 2978-2981 ◽  
Author(s):  
Jian Zhong Zhang ◽  
Xin Peng Xie ◽  
Chuan Jin Li ◽  
Ying Ying Xin ◽  
Zhao Ming He
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Theoretical Foundation ◽  
Future Research ◽  
Element Analysis ◽  
Pick And Place ◽  
Integral Structure ◽  
Inverse Dynamics Analysis ◽  
Three Degrees Of Freedom

This paper describes a parallel three degrees of freedom delta mechanism used for pick-and-place. It has the advantages of simple integral structure, strong bearing capacityhigh precisionkinematics and dynamics performance. According to this mechanism wide development prospect, the company study on the inverse kinematics inverse dynamics analysis and the static analysis by using ANSYS finite element analysis Software of Delta. These analyses have laid a good theoretical foundation for future research. These researches provide possible for widely used in foodpackingautomated assembly line occasions of small and medium-sized enterprises.

Optimal Design of a 3-DOF Parallel Micromanipulator

2009 ◽  
Author(s):  
Dan Zhang ◽  
Zhen Gao ◽  
Beizhi Li
Keyword(s):  
Fiber Optics ◽  
Biomedical Engineering ◽  
Degrees Of Freedom ◽  
Radial Basis Function Networks ◽  
Element Analysis ◽  
Optics Industry ◽  
And Performance ◽  
And Behavior ◽  
Resultant Stress ◽  
Three Degrees Of Freedom

A new compliant parallel micromanipulator is proposed in this paper. The manipulator has three degrees of freedom (DOF) and can generate motions in a microscopic scale. It can be used for biomedical engineering and fiber optics industry. In the paper, the detailed design of the structure is first introduced, followed by the kinematic analysis and performance evaluation. Second, a finite-element analysis of resultant stress, strain, and deformations is evaluated based upon different inputs of the three piezoelectric actuators. Finally, the genetic algorithms and radial basis function networks are implemented to search for the optimal architecture and behavior parameters in terms of global stiffness, dexterity and manipulability.

Multibody Analysis and Design of a Reconfigurable Parallel Kinematics Manipulator

2015 ◽  
Author(s):  
Matteo Palpacelli ◽  
Massimo Callegari ◽  
Luca Carbonari ◽  
Giacomo Palmieri
Keyword(s):  
Control Strategy ◽  
Degrees Of Freedom ◽  
Parallel Kinematics ◽  
Analysis And Design ◽  
Pure Rotation ◽  
Analytic Expressions ◽  
Robot Leg ◽  
Moving Platform ◽  
Actuation Systems ◽  
Three Degrees Of Freedom

This paper presents the design of a reconfigurable parallel kinematics machine endowed with three degrees of freedom of pure translation, or alternately of pure rotation. Such reconfigurability results from the use of lockable spherical joints, which realize the connection between each robot leg and the moving platform. Three actuated legs are used to drive the platform motion. The change of configuration occurs only at a specific pose, called home configuration. A control strategy allows to manage the shift phase and activate the two mobilities one at a time. Multibody simulations allowed to analyze the dynamic behavior of the manipulator and to verify the choices made with regard to the robot mechanics and the size of actuation systems. Position and differential kinematics of the manipulator are briefly introduced in order to demonstrate the simplicity of the analytic expressions and the mechanical feasibility of the manipulator.

scholarly journals FEATURES OF CHOOSING A ROLLING BEARING FOR A SPHERICAL TRANSFORMING MECHANISM

2020 ◽  
pp. 52-54
Author(s):  
A. Popov ◽  
I. Notov
Keyword(s):  
Degrees Of Freedom ◽  
Rolling Bearing ◽  
Spherical Mechanism ◽  
Three Degrees Of Freedom

The article presents the rationale for choosing a rolling bearing for a spherical mechanism with two and three degrees of freedom. Calculation schemes for determining the direction and values of active forces are given. Recommendations are given for selecting a rolling bearing based on the forces acting on the mechanism elements.

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