A Direct Determination of the Instantaneous Kinematics of Fully Parallel Robot Manipulators

1985 ◽  
Vol 107 (2) ◽  
pp. 226-229 ◽  
Author(s):  
M. G. Mohamed ◽  
J. Duffy
Keyword(s):  
Screw Theory ◽  
Robot Manipulators ◽  
Direct Determination ◽  
Parallel Robot ◽  
End Effector ◽  
Actuated Joints ◽  
Parallel Type

Screw theory is applied to the study of the instantaneous kinematics of the end-effector platform of fully parallel robot type devices. The instantaneous motion of the end-effector is expressed directly in terms of the twists of the input-actuated joints and it is demonstrated that the twist representing the instantaneous motion of the end-effector platform is equal to the sum of its partial twists. A partial twist is defined as the twist representing the instantaneous motion of the end-effector when all but one of the input actuators are locked. The analysis presented forms a proper basis for the study of special configurations of parallel type devices.

scholarly journals AN APPLICATION OF SCREW THEORY FOR THE IDENTIFICATION OF SINGULARITIES IN A NOVEL RECONFIGURABLE PARALLEL ROBOT

2016 ◽  
Vol 29 (2) ◽  
pp. 59-68 ◽  
Author(s):  
R.E. Sanchez-Alonso
Keyword(s):  
Screw Theory ◽  
Parallel Robot ◽  
Graphical Representations ◽  
Input Output ◽  
Jacobian Matrices ◽  
Singular Configurations ◽  
Output Equation

This paper reports the application of the screw theory as a tool for the determination of the singular configurations of a reconfigurable parallel robot composed of two parallel sub-manipulators. The Jacobian matrices of the robot, key elements for the identification of singularities, are easily determined when the input-output equation of velocity of the robot is obtained by the application of some screw theory basic operations. Through this application, the inverse, direct and combined singularities are clearly identified, and their graphical representations can be obtained almost intuitively.

Configuration Design of Modular 3-PRS Parallel Robot and Dynamic Simulation Analysis

2011 ◽  
Vol 130-134 ◽  
pp. 347-352
Author(s):  
Jing Tao Lei
Keyword(s):  
Control System ◽  
Screw Theory ◽  
Simulation Analysis ◽  
Integrated Design ◽  
Parallel Robot ◽  
Configuration Design ◽  
Prototype System ◽  
Three Dimension ◽  
End Effector ◽  
And Control

This paper presented model-based integrated design technology for configuration design of modular 3-PRS parallel robot. The kinematics screws matrix and constraint screws matrix of the end effector were obtained based on screw theory, the constraints of the end effector were analyzed and the degree of freedom of the robot can be determined. The forward kinematics of the parallel robot was analyzed according to the geometric relationship of a kinematics chain. Three-dimension solid model of the parallel robot was designed. Afterwards, the co-simulation of the mechanical and control system of the parallel robot was studied by applying virtual prototype technology to optimize the parameters of mechanical structure and control system. The simulation results of kinematics and dynamics can be obtained, which will offer basis for developing the prototype system.

Jacobian-based stiffness analysis method for parallel manipulators with non-redundant legs

2015 ◽  
Vol 230 (3) ◽  
pp. 341-352 ◽  
Author(s):  
Antonius GL Hoevenaars ◽  
Patrice Lambert ◽  
Just L Herder
Keyword(s):  
Parallel Manipulator ◽  
Screw Theory ◽  
Parallel Manipulators ◽  
Structural Elements ◽  
Analysis Method ◽  
End Effector ◽  
Stiffness Analysis ◽  
Compliant Joints ◽  
Lower Mobility ◽  
Actuated Joints

Stiffness is an important element in the model of a parallel manipulator. A complete stiffness analysis includes the contributions of joints as well as structural elements. Parallel manipulators potentially include both actuated joints, passive compliant joints, and zero stiffness joints, while a leg may impose constraints on the end-effector in the case of lower mobility parallel manipulators. Additionally, parallel manipulators are often designed to interact with an environment, which means that an external wrench may be applied to the end-effector. This paper presents a Jacobian-based stiffness analysis method, based on screw theory, that effectively considers all above aspects and which also applies to parallel manipulators with non-redundant legs.

SCREW-THEORY BASED METHODS FOR SOLVING THE INVERSE INSTANTANEOUS KINEMATICS OF 6 DOF MANIPULATORS

1992 ◽  
Vol 16 (1) ◽  
pp. 1-15
Author(s):  
R.G. Fenton ◽  
Xiaolun Shi
Keyword(s):  
Computational Efficiency ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Decomposition Methods ◽  
Joint Position ◽  
End Effector ◽  
Singular Configurations ◽  
Position Errors

Determination of joint velocities from a given Jacobian matrix and end-effector velocities requires an efficient and accurate algorithm. In this paper, two methods are introduced for this purpose, and compared with three existing methods on the basis of computational efficiency, accuracy, sensitivity to joint position errors and near-degenerate configurations, and capability of dealing with singular configurations. It is found that the two sequential screw-decomposition methods based on Gram-Schmidt Decompositions are the most efficient and computationally accurate methods, and they can also be effectively utilized to cope with singular configurations of the manipulators.

Determination of Joint Velocities of Robots by Using Screws

1984 ◽  
Vol 106 (2) ◽  
pp. 222-227 ◽  
Author(s):  
K. Sugimoto
Keyword(s):  
Screw Theory ◽  
Sampling Period ◽  
Trajectory Control ◽  
Orthogonal Basis ◽  
Industrial Robots ◽  
End Effector ◽  
Straight Line ◽  
Line Trajectory ◽  
Straight Line Trajectory

The screw theory is applied to determination of joint velocities of robot arms. The method described in this paper can be directly used for the straight line trajectory control of existing industrial robots. Joint velocities are computed by taking inner products of two kinds of screws, one of which is an element of an orthogonal basis of the screw system composed of joint screws and another is the screw representing an instantaneous motion of an end effector. The computation can be performed during a sampling period while a robot is in motion.

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

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