Computation of the safe working zones of Planar and Spatial Parallel Manipulators

Robotica ◽  
2019 ◽  
Vol 38 (5) ◽  
pp. 861-885 ◽  
Author(s):  
Murali K. Karnam ◽  
Aravind Baskar ◽  
Rangaprasad A. Srivatsan ◽  
Sandipan Bandyopadhyay

SUMMARYThis paper presents the computation of the safe working zone (SWZ) of a parallel manipulator having three degrees of freedom. The SWZ is defined as a continuous subset of the workspace, wherein the manipulator does not suffer any singularity, and is also free from the issues of link interference and physical limits on its joints. The proposed theory is illustrated via application to two parallel manipulators: a planar 3-R̲RR manipulator and a spatial manipulator, namely, MaPaMan-I. It is also shown how the analyses can be applied to any parallel manipulator having three degrees of freedom, planar or spatial.

Author(s):  
Dhruvesh Patel ◽  
Rohit Kalla ◽  
Halil Tetik ◽  
Gökhan Kiper ◽  
Sandipan Bandyopadhyay

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Jun Wu ◽  
Binbin Zhang ◽  
Liping Wang

The paper deals with the evaluation of acceleration of redundant and nonredundant parallel manipulators. The dynamic model of three degrees-of-freedom (3DOF) parallel manipulator is derived by using the virtual work principle. Based on the dynamic model, a measure is proposed for the acceleration evaluation of the redundant parallel manipulator and its nonredundant counterpart. The measure is designed on the basis of the maximum acceleration of the mobile platform when one actuated joint force is unit and other actuated joint forces are less than or equal to a unit force. The measure for evaluation of acceleration can be used to evaluate the acceleration of both redundant parallel manipulators and nonredundant parallel manipulators. Furthermore, the acceleration of the 4-PSS-PU parallel manipulator and its nonredundant counterpart are compared.


Author(s):  
H. R. Mohammadi Daniali ◽  
P. J. Zsombor-Murray ◽  
Jorge Angeles

Abstract The singularities of the Jacobian matrices of two manipulator with three degrees of freedom are analyzed. One is a planar 3-legged manipulator; the other, a planar double-triangular manipulator. A general classification of parallel-manipulator singularities into three groups is described. The classification scheme relies on the properties of the Jacobian matrices of the manipulator. Finally, the three types of singularity are identified for the two manipulators.


2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Jaime Gallardo-Alvarado ◽  
Ramon Rodriguez-Castro

In this work, a new parallel manipulator with multiple operation modes is introduced. The proposed robot is based on a three-degrees-of-freedom (3DOF) parallel manipulator endowed with a three-dof central kinematic chain, where by blocking some specific kinematic pairs, the robot can modify its mobility. Hence, the robot manipulator is able to assume the role of a limited-dof or a nonredundant parallel manipulator. Without loss of generality, the instantaneous kinematics of one member of the family of parallel manipulators generated by the reconfigurable parallel manipulator, the three-RPRRC + RRPRU nonredundant parallel manipulator with decoupled motions, is approached by means of the theory of screws. For the sake of completeness, the finite kinematics of the robot is also investigated. Numerical examples are included with the purpose to clarify the method of kinematic analysis.


2005 ◽  
Vol 33 (3) ◽  
pp. 251-259 ◽  
Author(s):  
H. R. Mohammadi Daniali

With regard to planar parallel manipulators, a general classification of singularities into three groups is given. The classification scheme relies on the properties of instantaneous centers of rotation. This method is very fast and can easily be applied to the manipulators under study. The method is applied to a planar three-degrees-of-freedom parallel manipulator and all its singular configurations are found.


2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Lingmin Xu ◽  
Qinchuan Li ◽  
Ningbin Zhang ◽  
Qiaohong Chen

Parallel manipulators (PMs) with redundant actuation are attracting increasing research interest because they have demonstrated improved stiffness and fewer singularities. This paper proposes a new redundantly actuated parallel manipulator that has three degrees-of-freedom (DOFs) and four limbs. The proposed manipulator is a 2UPR-2PRU parallel manipulator (where P represents an actuated prismatic joint, R represents a revolute joint, and U represents a universal joint) that is actuated using four prismatic joints; two of these joints are mounted on the base to reduce the movable mass. Mobility analysis shows that the moving platform has two rotational DOFs and one translational DOF. First, the inverse displacement solution, velocity, and singularity analyses are discussed. Next, the local transmission index (LTI) and the good transmission workspace are used to evaluate the motion/force transmissibility of the 2UPR-2PRU parallel manipulator. Finally, the parameter-finiteness normalization method (PFNM) is used to produce an optimal design that considers the good transmission workspace. It is thus shown that the motion/force transmission of the proposed manipulator is improved by optimizing the link parameters.


2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.


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