<abstract xmlns="http://www.w3.org/1999/xhtml"><p> The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism are studied and optimized. The stiffness of the robotic system in every single moveable direction is measured and analyzed, and it is observed that in the case where one tries to make the x and y translational stiffness larger, the z directional stiffness will be reduced, i.e. the x and y translational stiffness contradicts with the one in z direction. Subsequently, the objective functions for the summation of the x and y translational stiffness and z directional stiffness are established and they are being optimized simultaneously. However, we later found that these two objectives are not in the same scale; a normalization of the objectives is thus taken into consideration. Meanwhile, the robotic system’s workspace is studied and optimized. Through comparing the stiffness landscape and the workspace volume landscape, it is also observed that the z translational stiffness shows the same changing tendency with the workspace volume’s changing tendency while the x and y translational stiffness shows the opposite changing tendency compared to the workspace volume’s. Via employing the Pareto front theory and differential evolution, the summation of the x and y translational stiffness and the volume of the workspace are being simultaneously optimized. Finally, the mechanism is employed to synthesize an exercise-walking machine for stroke patients.</p></abstract>

The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism are studied and optimized. The stiffness of the robotic system in every single moveable direction is measured and analyzed, and it is observed that in the case where one tries to make the x and y translational stiffness larger, the z directional stiffness will be reduced, i.e. the x and y translational stiffness contradicts with the one in z direction. Subsequently, the objective functions for the summation of the x and y translational stiffness and z directional stiffness are established and they are being optimized simultaneously. However, we later found that these two objectives are not in the same scale; a normalization of the objectives is thus taken into consideration. Meanwhile, the robotic system’s workspace is studied and optimized. Through comparing the stiffness landscape and the workspace volume landscape, it is also observed that the z translational stiffness shows the same changing tendency with the workspace volume’s changing tendency while the x and y translational stiffness shows the opposite changing tendency compared to the workspace volume’s. Via employing the Pareto front theory and differential evolution, the summation of the x and y translational stiffness and the volume of the workspace are being simultaneously optimized. Finally, the mechanism is employed to synthesize an exercise-walking machine for stroke patients.

Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

Department of Mechanical Engineering, Lassonde School of Engineering, York University, 4700 Keele Street, Toronto ON. M3J 1P3,

Measurement Science Review

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism...

Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

Published Online: Apr 26, 2017

Page range: 83 - 92

Received: Nov 09, 2016

Accepted: Mar 31, 2017

DOI: https://doi.org/10.1515/msr-2017-0011

Keywords
Robotic manipulator, stiffness, workspace, interactions, optimization, walking machine

© by Dan Zhang

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

Published Online: Apr 26, 2017

Page range: 83 - 92

Received: Nov 09, 2016

Accepted: Mar 31, 2017

DOI: https://doi.org/10.1515/msr-2017-0011

KeywordsRobotic manipulator, stiffness, workspace, interactions, optimization, walking machine

© by Dan Zhang

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
Robotic manipulator, stiffness, workspace, interactions, optimization, walking machine