On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators

Serially connected statically balanced manipulators with springs have been used in many applications. However, a portion of the torques caused by springs countering each other lead to an imbalance in gravitational torques and, therefore, are deemed as waste torques for springs to achieve static bala...

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Main Authors: Chi-Shiun Jhuang, Chia-Wei Juang, Cheng-Hsin Shih, Dar-Zen Chen
Format: Article
Language:English
Published: MDPI AG 2023-02-01
Series:Machines
Subjects:
Online Access:https://www.mdpi.com/2075-1702/11/2/200
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author Chi-Shiun Jhuang
Chia-Wei Juang
Cheng-Hsin Shih
Dar-Zen Chen
author_facet Chi-Shiun Jhuang
Chia-Wei Juang
Cheng-Hsin Shih
Dar-Zen Chen
author_sort Chi-Shiun Jhuang
collection DOAJ
description Serially connected statically balanced manipulators with springs have been used in many applications. However, a portion of the torques caused by springs countering each other lead to an imbalance in gravitational torques and, therefore, are deemed as waste torques for springs to achieve static balance. In this paper, the torque contribution of a typical spring is classified as gravity-balancing torque and counter-torque based on the accumulated joint angle of the gravitational torque. Then, the internal counter-torque is defined as the sum of the magnitude of the terms of these counter-torques at each joint. Through the adjustment of spring attachment parameters, the internal counter-torque can be minimized with preferable spring attachment parameters while maintaining a static-balancing condition. A typical four-link manipulator with a preselected spring configuration is shown as an illustrative example. The results show that there are 28% and 50% reductions in the internal counter-torque at joints 2 and 3, respectively, through the adjustment of spring attachment parameters. Hence, the waste torques in statically balanced serially connected manipulators are reduced to the lowest quantity.
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spelling doaj.art-dfe5cecd8f87419990397a1267c545c12023-11-16T21:45:16ZengMDPI AGMachines2075-17022023-02-0111220010.3390/machines11020200On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced ManipulatorsChi-Shiun Jhuang0Chia-Wei Juang1Cheng-Hsin Shih2Dar-Zen Chen3Department of Mechanical Engineering, National Taiwan University, Taipei 10617, TaiwanDepartment of Mechanical Engineering, National Taiwan University, Taipei 10617, TaiwanDepartment of Mechanical Engineering, National Taiwan University, Taipei 10617, TaiwanDepartment of Mechanical Engineering, National Taiwan University, Taipei 10617, TaiwanSerially connected statically balanced manipulators with springs have been used in many applications. However, a portion of the torques caused by springs countering each other lead to an imbalance in gravitational torques and, therefore, are deemed as waste torques for springs to achieve static balance. In this paper, the torque contribution of a typical spring is classified as gravity-balancing torque and counter-torque based on the accumulated joint angle of the gravitational torque. Then, the internal counter-torque is defined as the sum of the magnitude of the terms of these counter-torques at each joint. Through the adjustment of spring attachment parameters, the internal counter-torque can be minimized with preferable spring attachment parameters while maintaining a static-balancing condition. A typical four-link manipulator with a preselected spring configuration is shown as an illustrative example. The results show that there are 28% and 50% reductions in the internal counter-torque at joints 2 and 3, respectively, through the adjustment of spring attachment parameters. Hence, the waste torques in statically balanced serially connected manipulators are reduced to the lowest quantity.https://www.mdpi.com/2075-1702/11/2/200internal counter-torqueserially connected manipulatorsstatic balance
spellingShingle Chi-Shiun Jhuang
Chia-Wei Juang
Cheng-Hsin Shih
Dar-Zen Chen
On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
Machines
internal counter-torque
serially connected manipulators
static balance
title On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
title_full On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
title_fullStr On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
title_full_unstemmed On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
title_short On the Internal Counter-Torque between Springs in Serially Connected Statically Balanced Manipulators
title_sort on the internal counter torque between springs in serially connected statically balanced manipulators
topic internal counter-torque
serially connected manipulators
static balance
url https://www.mdpi.com/2075-1702/11/2/200
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AT chenghsinshih ontheinternalcountertorquebetweenspringsinseriallyconnectedstaticallybalancedmanipulators
AT darzenchen ontheinternalcountertorquebetweenspringsinseriallyconnectedstaticallybalancedmanipulators