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Wu. Intell Robot 2021;1(2):99­115 Intelligence & Robotics
DOI: 10.20517/ir.2021.11

Research Article Open Access

On the elastodynamics of a five-axis lightweight an-
thropomorphic robotic arm

Guanglei Wu

School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China.
Correspondence to: Dr. Guanglei Wu, School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, Liaoning,
China. E-mail: gwu@dlut.edu.cn
How to cite this article: Wu GL. On the elastodynamics of a five-axis lightweight anthropomorphic robotic arm. Intell Robot
2021;1(2):99-115. http://dx.doi.org/10.20517/ir.2021.11

Received: 17 Sep 2021 First Decision: 22 Oct 2021 Revised: 12 Nov 2021 Accepted: 18 Nov 2021 Published: 1 Dec 2021
Academic Editors: Simon X. Yang, Howard Li Copy Editor: Xi-Jun Chen Production Editor: Xi-Jun Chen

Abstract
This paper presents elastodynamic modeling and analysis for a five-axis lightweight robotic arm. Natural frequencies
are derived and visualized within the dexterous workspace to show the overall performances and compare them to
the frequencies when the robotics is with payload. The comparison shows that the payload has a relatively small
influence to the first- and second-order frequencies. Sensitivity analysis is conducted, and the system’s frequency is
more sensitive to the second joint stiffness than the others. Moreover, observations from the displacement response
analysis reveal that the robotics produces linear elastic displacements of the same level between the loaded and
unloaded working modes but larger rotational deflections under the loaded working condition. The main contribution
of this work lies in that a systematic approach of elastodynamic analysis for serial robotic manipulators is formulated,
where the arm gravity and external load are taken into account to investigate the dynamic behaviors of the robotic
arms, i.e., frequencies, sensitivity analysis, and displacement responses, under the loaded mode.

Keywords: Lightweight robotic arm, elastodynamics, natural frequency, displacement response

1. INTRODUCTION
Lightweight robotic arms and anthropomorphic assistive robots with high payload capacity are desired for
applications of industry and welfare, among other fields, such as assisted daily living [1–3] , pick-and-place op-
[4]
erations , etc. Pick-and-place robots are well suited for a static environment where the task is repeated and
[5]
precise tolerances are demanded . As a mechanical system, the dynamic characteristics of the robotic arm

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0
International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, shar­
ing, adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as long as you
give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate
if changes were made.

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