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Optimization and Trajectory Planning of a 3-DOF Planar Parallel Micro-Manipulator
- Author(s)
- DONG Yanlu
- Advisor
- 이문구
- Department
- 일반대학원 기계공학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2012-08
- Language
- eng
- Alternative Abstract
- With the advantages of high speed and carrying capacity, good dynamic performance, low cost and compact structure, parallel robots have a good prospect of application. The main motivation behind the use of such mechanisms is that they provide better stiffness and accuracy than serial kinematic chains. Nowadays, parallel robots are widely used as flight simulators, auto mobile simulators and optical fiber alignment. They also become more popular in manufacturing process, as high speed/high precision milling machines and as micro assembling manipulators. However, one shortcoming of parallel manipulators is the particular configuration of the mechanism results in smaller workspace than their serial counterparts. That is because of the additional constraints imposed by the closed kinematic chains of these mechanisms. In the parallel robot design, the key point is structural parameter selection, which directly affects the mechanism performance such as workspace and dexterity. Therefore, optimization design of the parallel structure parameters becomes a very important issue. In this work, the 3-PRR, a new planar parallel manipulator which helps greatly to increase their maneuverability and enlarging their workspace, is presented. The planar parallel Manipulator has symmetric three identical PRR legs, with fixed prismatic actuators, connecting from the fixed base to the end-effecter. First, the constraint features, position formulations, inverse kinematics and workspace of 3-PRR planar parallel manipulator will be introduced. Those will provide theory basis for the following kinematics and workspace optimization. Second, optimization design will be considered with 2 aspects: workspace and dexterity. The workspace is the working area of the moving platform. Its size and shape is a very important indicator to measure the performance of the mechanisms. Monte Carlo Method is applied to determine the optimum parameter with the largest workspace. Dexterity is another indicator to show whether the mechanism is in good performance or not. Based on Global Condition Index, parameter will be optimized with the aim of finding the best dexterity. As the selection of the parallel kinematic parameter can affect both workspace and dexterity, losses will be incurred to the other hand by unilateral optimization. After the two optimizations, a multi-objective optimization problem will be finally proposed in order to determine optimum kinematic parameter with a required workspace and a better dexterity. The optimization method which mentioned above will be achieved by using Matlab Optimization Toolbox. Finally, a point-to-point trajectory is planned for this parallel manipulator using fifth-order polynomials. The motion undergone by desired trajectory should be as smooth as possible, abrupt changes in position, velocity, and acceleration should be avoided. Simulation of the trajectory and an experiment will be carried out to test the trajectory planning.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Mechanical Engineering > 3. Theses(Master)
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