scholarly journals Coupling analysis of a 5-degree-of-freedom hybrid manipulator based on a global index

2020 ◽  
Vol 103 (1) ◽  
pp. 003685041988189 ◽  
Author(s):  
Yanqin Zhao ◽  
Jiangping Mei ◽  
Wentie Niu ◽  
Mingkun Wu ◽  
Fan Zhang
Keyword(s):  
Degree Of Freedom ◽  
Global Index ◽  
Essential Information ◽  
Automotive Manufacturing ◽  
Parallel Kinematic Machines ◽  
Coupling Index ◽  
Hybrid Manipulator ◽  
Parallel Kinematic ◽  
Coupling Characteristics ◽  
And Control

Parallel kinematic machines have been applied in aerospace and automotive manufacturing due to their potentials in high speed and high accuracy. However, there exists coupling in parallel kinematic machines, which makes dynamic analysis, rigidity enhancement, and control very complicated. In this article, coupling characteristics of a 5-degree-of-freedom (5-dof) hybrid manipulator are analyzed based on a local index and a global index. First, velocity analysis as well as acceleration analysis of the robot is conducted to provide essential information for dynamic modeling. Then the dynamic model is built based on the principle of virtual work. Whereas the mass matrix is off-diagonal, a local coupling index as well as a global index is defined, based on which coupling characteristics of the robot are analyzed. Results show that distributions of coupling indices are symmetric due to its structural features. And dimensional parameters, structural parameters, as well as mass parameters have a large influence on the system’s coupling characteristics. Research conducted in the article is of great help in optimal design and control. Meanwhile, the method proposed in the article can be applied to other types of parallel kinematic machines or hybrid manipulators.

Accuracy Synthesis of a 3-PRS Parallel Manipulator Based on Genetic Algorithms

2010 ◽  
Vol 97-101 ◽  
pp. 3432-3435
Author(s):  
Tao Sun ◽  
Yi Min Song ◽  
Liang Xu
Keyword(s):  
Mathematical Model ◽  
Genetic Algorithms ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
Tolerance Range ◽  
Parallel Kinematic Machines ◽  
Limited Degree ◽  
Parallel Kinematic ◽  
The Mathematical Model

The existence of the non-compensable errors in limited-degree-of-freedom (limited-DoF) parallel kinematic machines (PKMs) affects the accuracy of mechanism and decreases the location capability. A 3-PRS parallel manipulator as an example, this paper formulates the mathematical model of the accuracy synthesis of the manipulator and carries out the accuracy synthesis based on the genetic algorithms, and then obtains the tolerance range of the non-compensable errors in the manufacture and the assembly.

Analysis of Stiffness and Elastic Deformation for Some 3–5-DOF PKMs With SPR or RPS-type legs

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Yi Lu ◽  
Bo Hu
Keyword(s):  
Elastic Deformation ◽  
Degree Of Freedom ◽  
Geometric Constraints ◽  
Elastic Deformations ◽  
Jacobian Matrices ◽  
Parallel Kinematic Machines ◽  
Stiffness Matrices ◽  
Parallel Kinematic ◽  
Equivalent Mechanism

This paper proposes an equivalent mechanism approach for establishing the stiffness matrices of some 3–5DOF (degree of freedom) parallel kinematic machines (PKMs) with SP̱R- or RP̱S-type legs and solving their elastic deformations. First, the geometric constraints of constrained wrench of these PKMs are analyzed, and the poses of the active/constrained forces are determined. Second, based on the principle of virtue work and the determined active/constrained forces, the formulas are derived for solving the 6×6 Jacobian matrices of these PKMs and the stiffness matrices of SP̱R or RP̱S-type active legs. Third, based on the elastic deformations of the SP̱R or RP̱S active legs, the equivalent 6-DOF rigid PKMs of these elastic PKMs are constructed, and their 6×6 Jacobian matrices are derived. Finally, the formulas are derived for solving the total stiffness matrices and the elastic deformation of the 3DOF 3SP̱R, 3DOF 3RP̱S, 4DOF 2SP̱S+2SP̱R, and 5DOF 4SP̱S+SP̱R PKMs.

scholarly journals Conceptual design and comparative stiffness analysis of an Exechon-like parallel kinematic machine with lockable spherical joints

2017 ◽  
Vol 14 (4) ◽  
pp. 172988141772413
Author(s):  
Teng-fei Tang ◽  
Jun Zhang
Keyword(s):  
Conceptual Design ◽  
Prediction Accuracy ◽  
Parallel Kinematic Machine ◽  
Stiffness Analysis ◽  
Parallel Kinematic Machines ◽  
Stiffness Model ◽  
Dynamic Analyses ◽  
Parallel Kinematic ◽  
Kinetostatic Model ◽  
Limb Structure

This article proposes two types of lockable spherical joints which can perform three different motion patters by locking or unlocking corresponding rotational axes. Based on the proposed lockable spherical joints, a general reconfigurable limb structure with two passive joints is designed with which the conceptual designs of two types of Exechon-like parallel kinematic machines are completed. To evaluate the stiffness of the proposed Exechon-like parallel kinematic machines, an expanded kinetostatic model is established by including the compliances of all joints and limb structures. The prediction accuracy of the expanded stiffness model is validated by numerical simulations. The comparative stiffness analyses prove that the Exe-Variant parallel kinematic machine claims competitive rigidity performance to the Exechon parallel kinematic machine. The present work can provide useful information for further investigations on structural enhancement, rigidity improvement, and dynamic analyses of other Exechon-like parallel kinematic machines.

scholarly journals Portable Take-Home System Enables Proportional Control and High-Resolution Data Logging with a Multi-Degree-of-Freedom Bionic Arm

2020 ◽  
Author(s):  
Mark Brinton ◽  
Elliott Barcikowski ◽  
Tyler Davis ◽  
Michael Paskett ◽  
Jacob George ◽  
...  
Keyword(s):  
Force Sensor ◽  
Degree Of Freedom ◽  
Future Research ◽  
High Temporal Resolution ◽  
Data Logging ◽  
Essential Information ◽  
Proportional Control ◽  
High Resolution Data ◽  
Manual Tasks ◽  
At Home

AbstractThis paper describes a portable, prosthetic control system for at-home use of an advanced bionic arm. The system uses a modified Kalman filter to provide 6 degree-of-freedom, real-time, proportional control. We describe (a) how the system trains motor control algorithms for use with an advanced bionic arm, and (b) the system’s ability to record an unprecedented and comprehensive dataset of EMG, hand positions and force sensor values. Intact participants and a transradial amputee used the system to perform activities-of-daily-living, including bi-manual tasks, in the lab and at home. This technology enables at-home dexterous bionic arm use, and provides a high-temporal resolution description of daily use—essential information to determine clinical relevance and improve future research for advanced bionic arms.

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