Analytical Study of Reachable Workspace for 2-RPR Planar Parallel Mechanisms

Author(s):  
Mahdi Agheli ◽  
Stephen S. Nestinger ◽  
Robert L. Norton

In both planar and spatial parallel mechanisms, selection of the structural parameters for a desired workspace generally employs the use of numerical methods. However, using the closed-form solution, if it exists, facilitates workspace-based design and optimization of the mechanism, and may significantly reduce the required time and calculation for finding the workspace of the mechanism. This paper presents a general and comprehensive closed-form solution for the reachable workspace of a 2-RPR planar parallel mechanism. The workspace of the mechanism is analyzed step-by-step in detail and its boundary is derived analytically. Since the solution is closed-form, it has high accuracy and reliability. Furthermore, the provided solution can be employed to solve the workspace of similar mechanisms in a closed-form manner including other n-RPR planar parallel mechanisms.

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Mahdi Agheli ◽  
Stephen S. Nestinger

The workspace of hexapod robots is a key performance parameter which has attracted the attention of numerous researchers during the past decades. The selection of the hexapod parameters for a desired workspace generally employs the use of numerical methods. This paper presents a general methodology for solving the closed-form constant orientation workspace of radially symmetric hexapod robots. The closed-form solution facilitates hexapod robot design and minimizes numerical efforts with on-line determination of stability and workspace utilization. The methodology can be used for robots with nonsymmetric and nonidentical kinematic chains. In this paper, the methodology is used to derive the closed-form equations of the boundary of the constant-orientation workspace of axially symmetric hexapod robots. Several applications are provided to demonstrate the capability of the presented closed-form solution in design and optimization. An approach for workspace-based design optimization is presented using the provided analytical solution by applying an iterative optimization algorithm to the find optimized structural parameters and an optimized workspace.


2015 ◽  
Vol 9 (6) ◽  
pp. 765-774 ◽  
Author(s):  
Wanjin Guo ◽  
◽  
Ruifeng Li ◽  
Chuqing Cao ◽  
Yunfeng Gao ◽  
...  

Application of hybrid robotics is a continuously developing field, as hybrid manipulators have demonstrated that they can combine the benefits of serial structures and parallel mechanisms. In this paper, a novel 5-degree-of-freedom hybrid manipulator is designed. The structure of this manipulator and its kinematics analysis are presented. An innovative closed-form solution was proposed to address the inverse kinematics problem. Additionally, the validity of the closed-form solution was verified via co-simulation using MATLAB and ADAMS. Finally, the reachable workspace of this manipulator was obtained for further optimizing the structure and motion control.


Author(s):  
Srimani Bhamidipati ◽  
Mahesh Panchagnula ◽  
John Peddieson

The application of fully Eulerian "multi-fluid" models to air blast atomization is discussed. Such models envision the system as consisting one carrier fluid phase and multiple drop phases, each having a discrete size. A model problem is formulated which allows a general closed form solution in terms of recurrence relations. This closed form solution is employed to produce representative results. A selection of these is used to illustrate interesting aspects of the predictions.


2011 ◽  
Vol 2011 ◽  
pp. 1-19 ◽  
Author(s):  
M. Ayub ◽  
M. H. Tiwana ◽  
A. B. Mann ◽  
H. Zaman

The diffraction of sound from a semi-infinite soft duct is investigated. The soft duct is symmetrically located inside an acoustically lined but infinite duct. A closed-form solution is obtained using integral transform and Jones' method based on Wiener-Hopf technique. The graphical results are presented, which show how effectively the unwanted noise can be reduced by proper selection of different parameters. The kernel functions are factorized with different approaches. The results may be used to design acoustic barriers and noise reduction devices.


1992 ◽  
Vol 114 (1) ◽  
pp. 68-73 ◽  
Author(s):  
V. Parenti-Castelli ◽  
C. Innocenti

The forward displacement analysis (FDA) in closed form of two classes of new parallel mechanisms derived from the Stewart Platform Mechanism (SPM) is presented in this paper. These mechanisms, when a set of actuator displacements is given, become multiloop structures of type PRR-3S and PPR-3S, with P, R and S for prismatic, revolute and spherical pairs, whereas the SPM has the structure RRR-3S. Solving the FDA in closed form means finding all the possible positions and orientations of the output controlled link when a set of actuator displacements is given, or equivalently, finding all possible closures of the corresponding structure. The closed form analysis of the PRR-3S and PPR-3S structures here presented results in algebraic equations in one unknown of degree 16 and 12, respectively. Hence 16 and 12 closures of the corresponding structures can be obtained. Numerical examples confirm these new theoretical results.


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