Dimensional synthesis and dynamic manipulability of a planar two-degree-of-freedom parallel manipulator

2008 ◽  
Vol 222 (6) ◽  
pp. 1061-1069 ◽  
Author(s):  
J Wu ◽  
J Wang ◽  
L Wang ◽  
H Shao
Keyword(s):  
Condition Number ◽  
Parallel Manipulator ◽  
Virtual Work ◽  
Mean Value ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
Hybrid Machine Tool ◽  
Inertia Matrix ◽  
Output Ratio ◽  
Two Degree Of Freedom

This article deals with the dimensional synthesis and dynamic manipulability of a planar two-degree-of-freedom (DOF) parallel manipulator. The dimensional synthesis based on the workspace and velocity output ratio is presented. The dynamic formulation is derived by using the virtual work principle. Taking into account that the accelerating capabilities at a given point along all directions are more isotropic, the condition number of inertia matrix in the dynamic equation is presented as an index to evaluate the dynamic manipulability of a manipulator. Furthermore, two global performance indices, which consider the mean value and standard deviation of the condition number of inertia matrix, are proposed, respectively. The dynamic manipulability of the parallel manipulator is more isotropic in the centre than at the peripheries of the workspace. The parallel manipulator is incorporated into a four-DOF hybrid machine tool, which also includes a two-DOF worktable.

Dynamic dexterity of a planar 2-DOF parallel manipulator in a hybrid machine tool

Robotica ◽  
2008 ◽  
Vol 26 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Jun Wu ◽  
Jinsong Wang ◽  
Tiemin Li ◽  
Liping Wang ◽  
Liwen Guan
Keyword(s):  
Condition Number ◽  
Parallel Manipulator ◽  
Virtual Work ◽  
Mean Value ◽  
Virtual Work Principle ◽  
Hybrid Machine Tool ◽  
Inertia Matrix ◽  
Inertial Parameters ◽  
Dynamic Formulation ◽  
The Mean

SUMMARYThis paper addresses the dynamic dexterity of a planar 2-degree of freedom (DOF) parallel manipulator with virtual constraint. Without simplification, the dynamic formulation is derived by using the virtual work principle. The condition number of the inertia matrix of the dynamic equation is presented as a criterion to evaluate the dynamic dexterity of a manipulator. In order to obtain the best isotropic configuration of the dynamic dexterity in the whole workspace, two global performance indices, which consider the mean value and standard deviation of the condition number of the inertia matrix, respectively, are proposed as the objective function. For a given set of geometrical and inertial parameters, the dynamic dexterity of the parallel manipulator is more isotropic in the center than at the boundaries of the workspace.

Motion Performance Analysis of Double-Cylinder Parallel Manipulators

2009 ◽  
Author(s):  
Hong Zhou ◽  
Shehu T. Alimi ◽  
Aravind Ravindranath ◽  
Hareesh Vepuri
Keyword(s):  
Performance Analysis ◽  
Parallel Manipulator ◽  
Critical Role ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Serial Manipulators ◽  
Operation Speed ◽  
Transmission Angle ◽  
Motion Performance ◽  
Two Degree Of Freedom

Double-cylinder parallel manipulators are closed-loop two-degree-of-freedom linkages. They are preferred to use because of their simplicity plus the common advantages of parallel manipulators such as high stiffness, load-bearing, operation speed and precision positioning. Like other parallel manipulators, the output motion of double-cylinder parallel manipulators is not as flexible as two-degree-of-freedom serial manipulators. The motion performance analysis plays a critical role for this type of parallel manipulator to be applied successfully. In this paper, the linkage feasibility conditions are established based on the transmission angle. When feasibility conditions are satisfied, there is no dead position during operation. The workspace is generated by using curve-enveloping theory. The singularity characteristics are analyzed within the workspace. The motion performance index contours within the workspace are produced using the condition number of the manipulator Jacobian matrix. The results of this paper provide guidelines to apply this type of parallel manipulator.

scholarly journals Simulation and Optimisation of a Two Degree of Freedom, Planar, Parallel Manipulator

2021 ◽  
Author(s):  
◽  
Ben Haughey
Keyword(s):  
Genetic Algorithm ◽  
Simulation Model ◽  
Cycle Time ◽  
Parallel Manipulator ◽  
Robotic Manipulators ◽  
Degree Of Freedom ◽  
End Effector ◽  
Planar Parallel Manipulator ◽  
Pick And Place ◽  
Two Degree Of Freedom

<p>Development in pick-and-place robotic manipulators continues to grow as factory processes are streamlined. One configuration of these manipulators is the two degree of freedom, planar, parallel manipulator (2DOFPPM). A machine building company, RML Engineering Ltd., wishes to develop custom robotic manipulators that are optimised for individual pick-and-place applications. This thesis develops several tools to assist in the design process. The 2DOFPPM’s structure lends itself to fast and accurate translations in a single plane. However, the performance of the 2DOFPPM is highly dependent on its dimensions. The kinematics of the 2DOFPPM are explored and used to examine the reachable workspace of the manipulator. This method of analysis also gives insight into the relative speed and accuracy of the manipulator’s end-effector in the workspace. A simulation model of the 2DOFPPM has been developed in Matlab’s® SimMechanics®. This allows the detailed analysis of the manipulator’s dynamics. In order to provide meaningful input into the simulation model, a cubic spline trajectory planner is created. The algorithm uses an iterative approach of minimising the time between knots along the path, while ensuring the kinematic and dynamic limits of the motors and end-effector are abided by. The resulting trajectory can be considered near-minimum in terms of its cycle-time. The dimensions of the 2DOFPPM have a large effect on the performance of the manipulator. Four major dimensions are analysed to see the effect each has on the cycle-time over a standardised path. The dimensions are the proximal and distal arms, spacing of the motors and the height of the manipulator above the workspace. The solution space of all feasible combinations of these dimensions is produced revealing cycle-times with a large degree of variation over the same path. Several optimisation algorithms are applied to finding the manipulator configuration with the fastest cycle-time. A random restart hill-climber, stochastic hill-climber, simulated annealing and a genetic algorithm are developed. After each algorithm’s parameters are tuned, the genetic algorithm is shown to outperform the other techniques.</p>

Dynamic Analysis and Counterweight Optimization of the 2-DOF Parallel Manipulator of a Hybrid Machine Tool

2007 ◽  
Vol 2 (4) ◽  
pp. 344-350 ◽  
Author(s):  
Jun Wu ◽  
Jinsong Wang ◽  
Liping Wang ◽  
Tiemin Li ◽  
Yue Liu
Keyword(s):  
Machine Tool ◽  
Parallel Manipulator ◽  
Cutting Tool ◽  
Force Model ◽  
Cutting Force Model ◽  
Dynamic Simulations ◽  
Hybrid Machine Tool ◽  
Planar Parallel Manipulator ◽  
Hybrid Machine ◽  
Two Degree Of Freedom

This paper focuses on the dynamic modeling and counterweight optimization of the two degree of freedom planar parallel manipulator, which is a subpart of a hybrid machine tool. Based on a kinematic analysis, the dynamic equation is derived by using the Newton-Euler approach. Then, three counterweight modes are presented for the parallel manipulator. According to the cutting force model and motion planning of the cutting tool, the dynamic simulations with three counterweight modes are performed, and the mass of counterweight in each counterweight mode is optimized by minimizing the sum of mean square values of actuator forces. The simulations show that the optimal mass of counterweights does not equal the total mass of moving parts of the parallel manipulator, and each counterweight mode has its advantage and disadvantage. Considering the ease in which a counterweight can be implemented, the counterweight mode where two counterweights are connected to two sliders is adopted for the parallel manipulator.

Design, analysis, and stiffness optimization of a three degree of freedom parallel manipulator

Robotica ◽  
2009 ◽  
Vol 28 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Zhen Gao ◽  
Dan Zhang ◽  
Xiaolin Hu ◽  
Yunjian Ge
Keyword(s):  
Parallel Manipulator ◽  
Optimization Methods ◽  
Inverse Kinematic ◽  
Mean Value ◽  
Optimization Techniques ◽  
Degree Of Freedom ◽  
Stiffness Optimization ◽  
Inverse Kinematic Analysis ◽  
Three Degree Of Freedom ◽  
Stiffness Distribution

SUMMARYThis paper proposed a novel three degree of freedom (DOF) parallel manipulator—two translations and one rotation. The mobility study and inverse kinematic analysis are conducted, and a CAD model is presented showing the design features. The optimization techniques based on artificial intelligence approaches are investigated to improve the system stiffness of the proposed 3-DOF parallel manipulator. Genetic algorithms and artificial neural networks are implemented as the intelligent optimization methods for the stiffness synthesis. The mean value and the standard deviation of the global stiffness distribution are proposed as the design indices. Both the single objective and multi-objective optimization issues are addressed. The effectiveness of this methodology is validated with Matlab.

Sign in / Sign up

Export Citation Format

Share Document