scholarly journals Forward kinematic analysis of a 3-RRRS mechanism with subordinate driving variables using a computer-aided geometric method

2019 ◽  
Vol 16 (4) ◽  
pp. 172988141987066
Author(s):  
Liangwen Wang ◽  
Tuanhui Wang ◽  
Fannian Meng ◽  
Wenliao Du ◽  
Caidong Wang ◽  
...  
Keyword(s):  
Analytical Method ◽  
Kinematic Analysis ◽  
Visual Basic ◽  
Geometric Method ◽  
Kinematics Analysis ◽  
Kinematic Chains ◽  
Computer Aided ◽  
Parameterized Model ◽  
Moving Platform ◽  
Analysis System

The 3-RRRS mechanism (RRRS refers to kinematic pairs of a branched chain consisting of three R pairs (Rotational pairs) and one S pair (Spherical pair), successively) is used between a moving platform and a static platform, through which six-dimensional motion of the moving platform relative to the static platform can be achieved. Selecting six independently drivable joints from nine active joints makes it problematic to deal analytically with the kinematics of the 3-RRRS mechanism. In this article, a novel computer-aided geometric method for kinematic analysis is developed. This method can automatically detect the independently drivable joints for arbitrary kinematic chains. This method can be easily implemented compared to the analytical method of the forward kinematics. Based on the constraint relationship of the 3-RRRS mechanism, a general 3-RRRS mechanism digital model is built in the SolidWorks Application Program Interface embedded Visual Basic environment, in which the platform sizes and active driving angles are driven by the parameterized model, to make the moving platform move to the corresponding pose. After the pose of the moving platform is confirmed, the coordinate system is built in a preliminary sketch. The parameters are measured by the SolidWorks measuring functions, and the pose of the moving platform is obtained by combining homogeneous matrices. Using the computer-aided geometric method, the detailed kinematics formula is not required. The accuracy and efficiency of the computer-aided geometric method were assessed with some examples of kinematic analysis for the 3-RRRS mechanism. The results showed that the proposed method obtained competitive precision and calculation time to the analytical method and is beneficial as a convenient solving process. By using Visual Basic programming, a reachable poses analysis of the mechanism can be merged into the kinematics analysis system of the computer-aided geometric method. The computer-aided geometric method could be widely applied to kinematics analysis of mechanisms.

Computer Aided Geometric Method of Forward Kinematics Analysis of Multi-Legged Walking Robots

2011 ◽  
Vol 317-319 ◽  
pp. 829-834
Author(s):  
Liang Wen Wang ◽  
Wei Gang Tang ◽  
Xin Jie Wang ◽  
Xue Wen Chen
Keyword(s):  
Visual Basic ◽  
Geometric Method ◽  
Walking Robots ◽  
Secondary Development ◽  
Forward Kinematics ◽  
Imaginary Root ◽  
Kinematics Analysis ◽  
Walking Robot ◽  
High Order Equation ◽  
Computer Aided

The high order equation causing by analytic method in multi-legged robot forward kinematics analysis may have imaginary root, repeated root, extraneous root or even lost solution. A system based on the theory of computer aided geometric method is proposed. Consideration with the internal structural constraint relations of multi-legged walking robots, the solidworks model was constructed and Visual Basic develop platform was adopted to fulfill the secondary development of solidworks. A system of forward kinematics analysis of multi-legged walking robots is established. The example validates that the system is simple and effective for all reptiles-like quadruped walking robot.

A serial of novel four degrees of freedom parallel mechanisms with large rotational workspace

Robotica ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 764-776 ◽  
Author(s):  
Sheng Guo ◽  
Wei Ye ◽  
Haibo Qu ◽  
Dan Zhang ◽  
Yuefa Fang
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Planetary Gear ◽  
Gear Train ◽  
Parallel Mechanisms ◽  
Kinematics Analysis ◽  
Kinematic Chains ◽  
Moving Platform ◽  
Partition Method

SUMMARYIn this paper, a class of novel four Degrees of Freedom (DOF) non-overconstrained parallel mechanisms with large rotational workspace is presented based on screw theory. First, the conflict between the number of independent constraints applied on the moving platform and the number of kinematic limbs for 4-DOF non-overconstrained parallel mechanism is identified. To solve this conflict, the platform partition method is introduced, and two secondary platforms are employed in each of the parallel mechanisms. Then, the motion requirements of the secondary platforms are analyzed and all the possible kinematic chains are enumerated. The geometrical assembly conditions of all possible secondary limbs are analyzed and some typical non-overconstrained parallel mechanisms are generated. In each of the parallel mechanisms, a planetary gear train is used to connect both of the secondary platforms. The large rotational workspace of the moving platform is obtained due to the relative motion of the two secondary platforms. Finally, the kinematics analysis of a typical parallel mechanism is conducted.

KINEMATICS AND WORKSPACE ANALYSIS OF A 3 DEGREE OF FREEDOM PARALLEL MECHANISM WITH PARALLELOGRAM LINKAGE

2017 ◽  
Vol 41 (5) ◽  
pp. 922-935
Author(s):  
HongJun San ◽  
JunSong Lei ◽  
JiuPeng Chen ◽  
ZhengMing Xiao ◽  
JunJie Zhao
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Analytical Method ◽  
Theoretical Basis ◽  
Parallel Mechanism ◽  
Graphical Method ◽  
Degree Of Freedom ◽  
Workspace Analysis ◽  
Fixed Base ◽  
Moving Platform

In this paper, a 3-DOF translational parallel mechanism with parallelogram linkage was studied. According to the space vector relation between the moving platform and the fixed base, the direct and inverse position solutions of this mechanism was deduced through analytical method. In addition, the error of the algorithm was analyzed, and the algorithm had turned out to be effective and to have the satisfactory computational precision. On the above basis, the workspace of this mechanism was found through graphical method, which was compared with that of finding through Monte Carlo method, and there was the feasibility for analyzing the workspace of the mechanism by graphical method. The characteristic of the mechanism was analyzed by comparing the results of two analysis methods, which provided a theoretical basis for the application of the mechanism.

ELEMENT-FREE METHODS VS. MESH-LESS CAE

2006 ◽  
Vol 03 (04) ◽  
pp. 445-464 ◽  
Author(s):  
HIDEYUKI SAKURAI
Keyword(s):  
Mesh Generation ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Generation Task ◽  
3D Objects ◽  
Computer Aided ◽  
Analysis System ◽  
Mesh Less ◽  
Element Free ◽  
Cae System

Element-free methods (EFreeMs) are expected to eliminate the mesh generation task. However, a computer aided engineering (CAE) system by EFreeM for complex three-dimensional (3D) objects has not yet been developed. This paper discusses the obstacles to the CAE and way to solve them. A 3D groundwater flow analysis system with an EFreeM is presented as a practical CAE. In the system, instead of pursuing mesh-less CAE, a unique mesh is employed to achieve the practical CAE. Some 3D examples show the performance and usefulness of the system. Two serious drawbacks of the EFreeM are also discussed from the viewpoint of the practical CAE.

scholarly journals A Novel Kinematically Redundant Planar Parallel Robot Manipulator With Full Rotatability

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicholas Baron ◽  
Andrew Philippides ◽  
Nicolas Rojas
Keyword(s):  
Potential Application ◽  
Robot Manipulator ◽  
Video Recording ◽  
Parallel Robot ◽  
Singularity Analysis ◽  
Geometric Method ◽  
Forward Kinematics ◽  
Online Video ◽  
End Effector ◽  
Moving Platform

This paper presents a novel kinematically redundant planar parallel robot manipulator, which has full rotatability. The proposed robot manipulator has an architecture that corresponds to a fundamental truss, meaning that it does not contain internal rigid structures when the actuators are locked. This also implies that its rigidity is not inherited from more general architectures or resulting from the combination of other fundamental structures. The introduced topology is a departure from the standard 3-RPR (or 3-RRR) mechanism on which most kinematically redundant planar parallel robot manipulators are based. The robot manipulator consists of a moving platform that is connected to the base via two RRR legs and connected to a ternary link, which is joined to the base by a passive revolute joint, via two other RRR legs. The resulting robot mechanism is kinematically redundant, being able to avoid the production of singularities and having unlimited rotational capability. The inverse and forward kinematics analyses of this novel robot manipulator are derived using distance-based techniques, and the singularity analysis is performed using a geometric method based on the properties of instantaneous centers of rotation. An example robot mechanism is analyzed numerically and physically tested; and a test trajectory where the end effector completes a full cycle rotation is reported. A link to an online video recording of such a capability, along with the avoidance of singularities and a potential application, is also provided.

scholarly journals 3D kinematic analysis of patients’ gait before and after unilateral total hip replacement

2020 ◽  
Vol 22 (2) ◽  
Author(s):  
Kateřina Kolářová ◽  
Tomáš Vodička ◽  
Michal Bozděch ◽  
Martin Repko
Keyword(s):  
Range Of Motion ◽  
Total Hip Replacement ◽  
Kinematic Analysis ◽  
Hip Replacement ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Step Length ◽  
Total Hip ◽  
Before And After ◽  
Analysis System

Purpose: The purpose of the study was to describe changes in the kinematic parameters in the patients’ gait after total hip replacement. Methods: Research group of men in the end stage of osteoarthritis indicated to the THR (n = 10; age 54.1 ± 7.5 years; weight 92.2 ± 9.6 kg; height 179.7 ± 5.9 cm). All participants underwent a total of three measurements: before surgery, 3 and 6 months after the surgery. Using the 3D kinematic analysis system, the patients’ gait was recorded during each measurement session and kinematic analysis was carried out. The parameters that were monitored included the sagittal range of motion while walking in the ankle, the knee and the hip joints of the operated and the unoperated limb, and the range in the hip joint’s frontal plane, the rotation of pelvis in the frontal and transverse planes, as well as the speed of walking and the walking step length. Results: Significant increases were found in sagittal range of motion in the operated hip joint, sagittal range of motion in the ankle joint on the unoperated side and in the walking step length of the unoperated limb. Conclusions: During walking after a THR, the sagittal range of motion in the ankle of the unoperated limb increases. Also, the range of motion in the sagittal plane on the operated joint increases, which is related to the lengthening of the step of the unoperated lower limb.

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