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Intelligent Service Robotics

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23-02-2022 | Original Research Paper

Feedforward operational stiffness modulation and external force estimation of planar robots equipped with variable stiffness actuators

Authors: Tatsuya Ohe, Tsige Tadesse Alemayoh, Jae Hoon Lee, Shingo Okamoto

Published in: Intelligent Service Robotics | Issue 2/2022

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Abstract

A variable stiffness actuator (VSA) is considered a promising mechanism-based approach for realizing compliant robotic manipulators. By changing the stiffness of each joint, the robot can modulate the stiffness of the entire system to enhance safety and efficiency during physical interaction with other systems. This paper presents a feedforward method to modulate the operational stiffness of a parallel planar robot with multiple VSAs. A VSA utilizing a lever mechanism was developed, clearly presenting its mechanical design and kinematic model details. A computational model of joint-restoring torque was developed based on deformation measurements and hysteresis loop geometry to estimate the applied torque of each joint in real-time. An algorithm was proposed to compute the joint stiffness solution using the robot's kinematic model for modulating the operational stiffness of the parallel robot. Experiments were performed to evaluate the proposed method by comparing the performances of two DOF serial and parallel robot systems. The results demonstrated the capability of the VSA in both feedforward stiffness modulation and external force estimation.

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Title: Feedforward operational stiffness modulation and external force estimation of planar robots equipped with variable stiffness actuators
Authors: Tatsuya Ohe
Tsige Tadesse Alemayoh
Jae Hoon Lee
Shingo Okamoto
Publication date: 23-02-2022
Publisher: Springer Berlin Heidelberg
Published in: Intelligent Service Robotics / Issue 2/2022
Print ISSN: 1861-2776
Electronic ISSN: 1861-2784
DOI: https://doi.org/10.1007/s11370-022-00412-y

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