1303 Singularity analysis of a 3-URU non-overconstrained spherical parallel mechanism with three degrees of freedom

2006 ◽  
Vol 2006.6 (0) ◽  
pp. 87-90
Author(s):  
Yukio Takeda ◽  
Syamsul Huda
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Spherical Parallel Mechanism ◽  
Three Degrees Of Freedom

Performance Analysis of 3-URU Spherical Parallel Mechanism Designed Based on Velocity Transmission and Force Constraint Indices

2015 ◽  
Vol 758 ◽  
pp. 71-76
Author(s):  
Syamsul Huda ◽  
Syafri ◽  
Mulyadi Bur
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Output Link ◽  
Kinematic Synthesis ◽  
Platform Motion ◽  
Spherical Parallel Mechanism ◽  
Velocity Transmission ◽  
Maximum Inclination ◽  
Three Degrees Of Freedom ◽  
Spherical Motion

In this paper was observed performances of developed three degrees of freedom (dof) parallel mechanism named 3-URU spherical parallel mechanism. The mechanism is composed of three identical limbs mounted symmetrically to base (fixed link) and platform (output link). The limb is constructed by universal-revolute and universal joints. The kinematic constants of mechanism consisting of link lengths, radius of platform, radius of base, mounting angle of limb and platform to base and platform were determined with consideration of velocity transmission and force constraint indices. To evaluate performance of mechanism, it was manufactured a prototype of mechanism designed base on these two mentioned indices. There are three steps proposed to realize the mechanism, (i) kinematic synthesis to determine of kinematic constants, (ii) design of mechanical components to define shape and dimension of links and joints by considering collision in wokingspace and static analysis, (iii) evaluation of mechanism performances consisting of workingspace, controllability of platform motion and static payload. Based on obtained results, it can be clarified that, the mechanism can produce spherical motion of platform which rotates on steady point recognized as center of platform rotation. The platform can achieve maximum inclination angle, 80 degree and at this posture occurs translational error, 0.0102 mm. On the other hand, the mechanism can support payload ten times of weight of moving parts.

scholarly journals A Sensor Based on a Spherical Parallel Mechanism for the Measurement of Fluid Velocity: Physical Modelling and Computational Analysis

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2867 ◽  
Author(s):  
Roque Saltarén ◽  
Gerardo Portilla ◽  
Alejandro Barroso ◽  
Juan Cely
Keyword(s):  
Parallel Mechanism ◽  
Inertial Measurement Unit ◽  
Degrees Of Freedom ◽  
Fluid Velocity ◽  
Physical Modelling ◽  
Measurement Unit ◽  
Adams Software ◽  
Spherical Parallel Mechanism ◽  
The Impact ◽  
Three Degrees Of Freedom

In this article, a new method was developed to measure the velocity of a fluid using a sensor, based on the use of a spherical parallel mechanism with three degrees-of-freedom (DOF). This sensor transforms the kinetic energy of the fluid into potential energy by deforming the parallel mechanism. This deformation is due to the impact of the fluid on a sphere attached to the platform of the parallel mechanism. Through the acquisition of data from a sensor using an inertial measurement unit (IMU) in the sphere, an algorithm calculates the velocity and direction of the fluid. In this article, a mathematical model of the mechanism and an algorithm for correctly measuring the velocity and direction of the fluid is developed; this algorithm is tested through a simulation in the Adams software, and the MATLAB software is used to execute the algorithm. The results show that the algorithm calculates the velocity and the direction of the fluid correctly, demonstrating the technical feasibility of the sensor.

Kinematics Analysis of a 3-RRR Spherical Parallel Mechanism with Coaxial Input Shafts

2013 ◽  
Vol 404 ◽  
pp. 237-243
Author(s):  
Yu Lei Hou ◽  
Xin Zhe Hu ◽  
Da Xing Zeng
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Inverse Solution ◽  
Kinematics Analysis ◽  
Motion Feature ◽  
Displacement Problem ◽  
Spherical Parallel Mechanism ◽  
Three Degrees Of Freedom

As an important mechanism with special and extensive application, the three degrees of freedom spherical parallel mechanism is always a research hot in the mechanical fields. In this paper, the feature of the 3-RRR spherical parallel mechanism with coaxial input shafts is introduced, and its motion feature is analyzed based on the screw theory. The mobility of the spherical parallel mechanism is calculated by using the Modified Kutzbach-Grübler criterion, and the inverse displacement problem of the mechanism is solved. Then the expression of the Jacobian matrix is deduced based on the kinematics equation and its inverse solution. The contents of this paper should be useful for the further application of the spherical parallel mechanism.

Mobility and singularity analyses of a symmetric multi-loop mechanism for space applications

2021 ◽  
pp. 095440622199555
Author(s):  
Chuanyang Li ◽  
Jorge Angeles ◽  
Hongwei Guo ◽  
Huiyin Yan ◽  
Dewei Tang ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Space Applications ◽  
Aerospace Applications ◽  
Constraint Analysis ◽  
Multi Stage ◽  
Prismatic Joints ◽  
The Subject ◽  
Three Degrees Of Freedom

A symmetric, double-tripod multi-loop mechanism (DTMLM), for aerospace applications, is the subject of this paper. Its mobility and singularity are analyzed, while introducing a novel tool, the cell-division method for singularity analysis, applicable to multi-loop mechanisms. The key principle of this method lies in replacing the singularity analysis of the original multi-loop mechanism with: (1) that of an equivalent simpler parallel mechanism; (2) the constraint analysis between loops; and (3) the singularity analysis of simpler kinematic subchains. Then, the mechanism is transformed into a simpler, equivalent parallel mechanism with three identical kinematic subchains. Its mobility and singularity are analyzed based on screw algebra, which leads to a key conclusion about the geometric properties of this mechanism. Results show that: (a) the DTMLM has three degrees of freedom (dof), i.e., two rotational dof around two intersecting axes lying in the middle plane of the mechanism, and one translational dof along the normal to the said plane (2R1T); and (b) the singularities of the 3-RSR parallel mechanism are avoided in the DTMLM by means of prismatic joints, singularities in the DTMLM occurring on the boundary of its workspace. Thus, the DTMLM has a 2R1T mobility everywhere within its workspace. When a set of multi-loop mechanisms of this kind are stacked as modules to assemble a multi-stage manipulator for space applications, the modules can be designed so that, under paradigm operations, all individual loops operate within their workspace, safe from singularities.

scholarly journals Optimum Seeking of Redundant Actuators for M-RCM 3-UPU Parallel Mechanism

2020 ◽  
Author(s):  
Chen Zhao ◽  
Jingke Song ◽  
Xuechan Chen ◽  
Ziming Chen ◽  
Huafeng Ding
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Universal Joint ◽  
Prismatic Joint ◽  
Transmission Index ◽  
Redundant Actuators ◽  
Force Transmissibility ◽  
Singular Configuration

Abstract This paper focuses on a 2R1T 3-UPU (U for universal joint and P for prismatic joint) parallel mechanism (PM) with two rotational and one translational (2R1T) degrees of freedom (DOFs) and the ability of multiple remote centers of motion (M-RCM). The singularity analysis based on the indexes of motion/force transmissibility and constraint shows that this PM has transmission singularity, constraint singularity, mixed singularity and limb singularity. To solve these singularproblems, the quantifiable redundancy transmission index (RTI) and the redundancy constraint index (RCI) are proposed for optimum seeking of redundant actuators for this PM. Then the appropriate redundant actuators are selected and the working scheme for redundant actuators near the corresponding singular configuration are given to help the PM go through the singularity.

Architecture Optmization of a 3-DOF Parallel Mechanism

1998 ◽  
Author(s):  
J. A. Carretero ◽  
R. P. Podhorodeski ◽  
M. Nahon
Keyword(s):  
Parallel Mechanism ◽  
Architectural Design ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Design Parameters ◽  
Objective Functions ◽  
Constraint Equations ◽  
Three Degree Of Freedom ◽  
Architecture Optimization ◽  
Three Degrees Of Freedom

Abstract This paper presents a study of the architecture optimization of a three-degree-of-freedom parallel mechanism intended for use as a telescope mirror focussing device. The construction of the mechanism is first described. Since the mechanism has only three degrees of freedom, constraint equations describing the inter-relationship between the six Cartesian coordinates are given. These constraints allow us to define the parasitic motions and, if incorporated into the kinematics model, a constrained Jacobian matrix can be obtained. This Jacobian matrix is then used to define a dexterity measure. The parasitic motions and dexterity are then used as objective functions for the optimizations routines and from which the optimal architectural design parameters are obtained.

Kinematics and Workspace Analysis of 3-RPP Parallel Mechanism

2013 ◽  
Vol 456 ◽  
pp. 146-150
Author(s):  
Zhi Jiang Xie ◽  
Jun Zhang ◽  
Xiao Bo Liu
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Parallel Mechanisms ◽  
Vector Method ◽  
Workspace Analysis ◽  
Inverse Solutions ◽  
Three Degrees Of Freedom

This paper designed a kind of parallel mechanism with three degrees of freedom, the freedom and movement types of the robot are analyzed in detail, the parallel mechanisms Kinematics positive and inverse solutions are derived through using the vector method. And at last its workspace is analyzed and studied systematically.

Singularity analysis of two-legged planar parallel robots with three degrees of freedom

2016 ◽  
Vol 232 (4) ◽  
pp. 657-664 ◽  
Author(s):  
Mustafa Özdemir
Keyword(s):  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
Design Concept ◽  
Type I ◽  
Numerical Examples ◽  
Three Degrees Of Freedom

Planar two-legged parallel robots with three degrees of freedom have been suggested in the literature as a solution to reduce the leg interference problem of their conventional three-legged counterparts, and since then have attracted considerable attention. This paper presents a singularity analysis of these robots. Three alternatives, namely the robots with 2-RRR, 2-RPR, and 2-PRR structures are considered. Type I, II, and III singularity conditions are obtained taking into account all possible actuation schemes. Several singularity-free actuation schemes are enumerated and discussed. The performed analysis also shows that adjustable designs are possible for manipulators with 2-PRR structures to have singularity-free operation. The proposed design concept and its effectiveness are illustrated through numerical examples.

Optimal synthesis of a spherical parallel mechanism for medical application

Robotica ◽  
2014 ◽  
Vol 34 (3) ◽  
pp. 671-686 ◽  
Author(s):  
T. Essomba ◽  
M. A. Laribi ◽  
S. Zeghloul ◽  
G. Poisson
Keyword(s):  
Motion Capture ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Medical Application ◽  
Optimal Synthesis ◽  
Objective Functions ◽  
Ultrasound Probe ◽  
Spherical Parallel Mechanism ◽  
Real Coded Genetic Algorithms ◽  
Probe Holder

SUMMARYThis paper introduces the design and the optimization of a probe holder robot for tele-echography applications. To define its kinematic architecture, an approach based on motion capture of an expert's gestures during ultrasound examinations was proposed. The medical gestures analyzed consisted of ultrasound probe movements and were used to characterize the kinematic specifications of the proposed manipulator. The selected architecture was a Spherical Parallel Mechanism (SPM) with 3 degrees of freedom (DoF) and its optimal synthesis was performed using real-coded Genetic Algorithms (GA). The optimization criteria and constraints were established thanks to the collaboration of medical experts and were successively formulated and solved using mono-objective and multi-objective functions.

scholarly journals A Translational Three-Degrees-of-Freedom Parallel Mechanism With Partial Motion Decoupling and Analytic Direct Kinematics

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Huiping Shen ◽  
Damien Chablat ◽  
Boxiong Zeng ◽  
Ju Li ◽  
Guanglei Wu ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Design Theory ◽  
Degrees Of Freedom ◽  
Analytic Solutions ◽  
Inverse Kinematic ◽  
Kinematic Modeling ◽  
Topological Design ◽  
Prismatic Joints ◽  
Topological Characteristics ◽  
Three Degrees Of Freedom

Abstract According to the topological design theory and the method of parallel mechanism (PM) based on position and orientation characteristic (POC) equations, this paper studied a three-degrees-of-freedom (3-DOF) translational PM that has three advantages, i.e., (i) it consists of three fixed actuated prismatic joints, (ii) the PM has analytic solutions to the direct and inverse kinematic problems, and (iii) the PM is of partial motion decoupling property. First, the main topological characteristics, such as the POC, degree-of-freedom, and coupling degree, were calculated for kinematic modeling. Thanks to these properties, the direct and inverse kinematic problems can be readily solved. Further, the conditions of the singular configurations of the PM were analyzed, which corresponds to its partial motion decoupling property.

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