A New Parallel Actuated Architecture for Exoskeleton Applications Involving Multiple Degree-of-Freedom Biological Joints

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Justin Hunt ◽  
Hyunglae Lee
Keyword(s):  
Parallel Manipulator ◽  
Dynamic Performance ◽  
Future Generation ◽  
Degree Of Freedom ◽  
Performance Requirements ◽  
Ankle Exoskeleton ◽  
And Control ◽  
Spherical Parallel Manipulator

The purpose of this work is to introduce a new parallel actuated exoskeleton architecture that can be used for multiple degree-of-freedom (DoF) biological joints. This is done in an effort to provide a better alternative for the augmentation of these joints than serial actuation. The new design can be described as a type of spherical parallel manipulator (SPM) that utilizes three 4 bar substructures to decouple and control three rotational DoFs. Four variations of the 4 bar spherical parallel manipulator (4B-SPM) are presented in this work. These include a shoulder, hip, wrist, and ankle exoskeleton. Also discussed are three different methods of actuation for the 4B-SPM, which can be implemented depending on dynamic performance requirements. This work could assist in the advancement of a future generation of parallel actuated exoskeletons that are more effective than their contemporary serial actuated counterparts.

A Novel Spherical Parallel Manipulator with Circular Guide

2013 ◽  
Vol 325-326 ◽  
pp. 1014-1018
Author(s):  
Hai Rong Fang ◽  
Zhi Hong Chen ◽  
Yue Fa Fang
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
High Rigidity ◽  
Geometric Conditions ◽  
Spherical Parallel Manipulator

In this paper, a novel 3-degree-of-freedom (DOF) parallel manipulator that can perform three rotations around the remote centre is presented. The theory of screws and reciprocal screws is employed for the analysis of the geometric conditions. In particular, using circular guide to instead of R joints, so that has the advantage of enabling continuous 360° revolute around Z-axis. The inverse kinematics of mechanism is given and the workspace has a good performance. To compare with the machine constructed with traditional joints, it has the advantage of high rigidity and precision.

Parametric Design of a Spherical Eight-Bar Linkage Based on a Spherical Parallel Manipulator

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Parametric Design ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Arbitrary Base ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator

This paper presents a procedure that determines the dimensions of two constraining links to be added to a three degree-of-freedom spherical parallel manipulator so that it becomes a one degree-of-freedom spherical (8, 10) eight-bar linkage that guides its end-effector through five task poses. The dimensions of the spherical parallel manipulator are unconstrained, which provides the freedom to specify arbitrary base attachment points as well as the opportunity to shape the overall movement of the linkage. Inverse kinematics analysis of the spherical parallel manipulator provides a set of relative poses between all of the links, which are used to formulate the synthesis equations for spherical RR chains connecting any two of these links. The analysis of the resulting spherical eight-bar linkage verifies the movement of the system.

A new closed-form kinematics of the generalized 3-DOF spherical parallel manipulator

Robotica ◽  
1999 ◽  
Vol 17 (5) ◽  
pp. 475-485 ◽  
Author(s):  
Zhen Huang ◽  
Y. Lawrence Yao
Keyword(s):  
Closed Form ◽  
Analytical Method ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
New Method ◽  
Numerical Example ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator

This paper presents a new method to analyze the closed-form kinematics of a generalized three-degree-of-a-freedom spherical parallel manipulator. Using this analytical method, concise and uniform solutions are achieved. Two special forms of the three-degree-of-freedom spherical parallel manipulator, i.e. right-angle type and a decoupled type, are also studied and their unique and interesting properties are investigated, followed by a numerical example.

Design and analysis of a totally decoupled 3-DOF spherical parallel manipulator

Robotica ◽  
2010 ◽  
Vol 29 (7) ◽  
pp. 1093-1100 ◽  
Author(s):  
Dan Zhang ◽  
Fan Zhang
Keyword(s):  
Physical Meaning ◽  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Jacobian Matrix ◽  
Degree Of Freedom ◽  
Redundant Constraints ◽  
Rotational Motions ◽  
Spherical Parallel Manipulator

SUMMARYIn this paper, we propose a unique, decoupled 3 degree-of-freedom (DOF) parallel wrist. The condition required for synthesizing a fully isotropic parallel mechanism is obtained on the basis of the physical meaning of the row vector in the Jacobian matrix. Specifically, an over-constrained spherical 3-DOF parallel mechanism is presented and the modified structure, which avoids the redundant constraints, is also introduced. The proposed manipulator is capable of decoupled rotational motions around the x, y, and z axes and contains an output angle that is equal to the input angle. As this device is analyzed with the Jacobian matrix, the mechanism is free of singularity within its workspace and maintains homogenous stiffness over the entire workspace.

scholarly journals Experimental Verification of Three-Degree-of-Freedom Electromagnetic Actuator for Image Stabilization

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2485
Author(s):  
Akira Heya ◽  
Katsuhiro Hirata
Keyword(s):  
Experimental Verification ◽  
Dynamic Performance ◽  
Autonomous Systems ◽  
Degree Of Freedom ◽  
Electromagnetic Actuator ◽  
Image Stabilization ◽  
Three Phase ◽  
Autonomous Cars ◽  
Three Degree Of Freedom ◽  
And Control

Image deteriorations due to vibrations have become a problem in autonomous systems such as unmanned aerial vehicles, robots, and autonomous cars. To suppress the vibration, a camera stabilizer using a gimbal mechanism is widely used. However, the size and weight of the system increase because the conventional image stabilization systems require some actuators and links to drive in multi-axes. In order to solve these problems, we proposed a novel three-degree-of-freedom (3DOF) electromagnetic actuator for image stabilization. The actuator can be driven by only three-phase and has a simple structure and control system. This paper describes the experimental verification of the proposed actuator. The torque characteristics are clarified, and the analysis and measured torque characteristics are compared to verify the analysis validity. For verifying the dynamic performance, the frequency characteristics are measured. The effectiveness of the proposed magnetic structure and operating principle are investigated.

Dynamic Performance With Control of a 2DOF Parallel Robot

2012 ◽  
Author(s):  
Gianmarc Coppola ◽  
Dan Zhang ◽  
Kefu Liu ◽  
Zhen Gao
Keyword(s):  
Dynamic Model ◽  
Performance Index ◽  
Parallel Manipulator ◽  
Dynamic Performance ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Performance Study ◽  
Linear Controller ◽  
Reachable Workspace ◽  
And Control

In this work the dynamic performance and control of a 2DOF parallel robot is conducted. The study is partly motivated by large variations in dynamic performance and control within the reachable workspace of many parallel manipulators. The forward dynamic model of the robot is derived in detail. The connection method is directly utilized for this derivation. Subsequently, a dynamic performance study is undertaken. This reveals important information whilst using a forward dynamic model. A performance index is proposed to determine the variability of performance of the parallel manipulator. Then a trajectory-tracking scenario is undertaken using a linear controller. By means of control, the simulations illustrate the validity of the proposed index for parallel manipulators.

Design and analysis of a 3-DOF spherical parallel manipulator – CORRECTED VERSION

Robotica ◽  
2011 ◽  
Vol 29 (7) ◽  
pp. 1109-1116 ◽  
Author(s):  
Dan Zhang ◽  
Fan Zhang
Keyword(s):  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
Redundant Constraints ◽  
Corrected Version ◽  
Spherical Parallel Manipulator

SUMMARYIn this paper, we propose a unique, 3 degree-of-freedom (DOF) parallel wrist. Specifically, an over-constrained spherical 3-DOF parallel mechanism is presented and the modified structure, which avoids the redundant constraints, is also introduced.

On the Direct Kinematics of Spherical Three-Degree-of-Freedom Parallel Manipulators with a Coplanar Platform

1994 ◽  
Vol 116 (2) ◽  
pp. 587-593 ◽  
Author(s):  
C. M. Gosselin ◽  
J. Sefrioui ◽  
M. J. Richard
Keyword(s):  
Parallel Manipulator ◽  
Minimal Polynomial ◽  
Polynomial Solution ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Real Solutions ◽  
Revolute Joints ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator ◽  
Direct Kinematics

This paper presents a polynomial solution to the direct kinematic problem of a class of spherical three-degree-of-freedom parallel manipulators. This class is defined as the set of manipulators for which the axes of the three revolute joints attached to the gripper link are coplanar and symmetrically arranged. It is shown that, for these manipulators, the direct kinematic problem admits a maximum of 8 real solutions. A polynomial of degree 8 is obtained here to support this result and cases for which all the roots of the polynomial lead to real configurations are presented. Finally, the spherical parallel manipulator with collinear actuators, which received some attention in the literature, is also treated and is shown to lead to a minimal polynomial of the same degree. Examples of the application of the method to manipulators of each category are given and solved.

Analysis of Two Spherical Parallel Manipulators With Hidden Revolute Joints

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Ju Li ◽  
J. Michael McCarthy
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Internal Constraints ◽  
Quadric Surfaces ◽  
Revolute Joints ◽  
Serial Chain ◽  
Point Of Intersection ◽  
Spherical Parallel Manipulator

In this paper, we examine two spherical parallel manipulators (SPMs) constructed with legs that include planar and spherical subchains that combine to impose constraints equivalent to hidden revolute joints. The first has supporting serial chain legs constructed from three revolute joints with parallel axes, denoted R∥R∥R, followed by two revolute joints that have intersecting axes, denoted RR̂. The leg has five degrees-of-freedom and is denoted R∥R∥R-RR̂. Three of these legs can be assembled so the spherical chains all share the same point of intersection to obtain a spherical parallel manipulator denoted as 3-R∥R∥R-RR̂. The second spherical parallel manipulator has legs constructed from three revolute joints that share one point of intersection, denoted RRR̂, and a second pair of revolute joints with axes that intersect in a different point. This five-degree-of-freedom leg is denoted RRR̂-RR̂. The spherical parallel manipulator constructed from these legs is 3-RRR̂-RR̂. We show that the internal constraints of these two types of legs combine to create hidden revolute joints that can be used to analyze the kinematics and singularities of these spherical parallel manipulators. A quaternion formulation provides equations for the quartic singularity varieties some of which decompose into pairs of quadric surfaces which we use to classify these spherical parallel manipulators.

An Efficient Inverse Acceleration Analysis of In-Parallel Manipulators

1996 ◽  
Author(s):  
José María Rico Martínez ◽  
Joseph Duffy
Keyword(s):  
Parallel Manipulator ◽  
Computing Time ◽  
Parallel Manipulators ◽  
Simple Expression ◽  
Degree Of Freedom ◽  
Simple Method ◽  
Dynamics And Control ◽  
Acceleration Analysis ◽  
Klein Form ◽  
And Control

Abstract A very simple novel expression for the accelerations of the six prismatic actuators, of the HPS connector chains, of a 6 degree of freedom in-parallel manipulator is derived. The expression is obtained by firstly computing the “accelerator” for a single HPS connector chain in terms of the joint velocities and accelerations. The accelerator is a function of the line coordinates of the joint axes and of a sequence of Lie products of the same line coordinates. A simple expression for the acceleration of the prismatic actuator is obtained by forming the Klein form, or reciprocal product, with the accelerator and the coordinates of the line of the connector chain. Since the Klein form is invariant, the resulting expression can be applied directly to the six HPS connector chains of an in-parallel manipulator. The authors believe that this simple method has important applications in the dynamics and control of these in-parallel manipulators where the computing time must be minimized to improve the behavior of parallel manipulators.

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