A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling

Due to its exceptional terrain mobility, quadrupedal locomotion has been used in the design of many amphibious robots for broad applications including resource exploration, disaster rescue, and reconnaissance. In this work, swimming of a quadrupedal paddling model is considered, and the effects of t...

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Main Authors: Yihan Wang, Yumeng Cai, Bin Xie, Chi Zhu, Yunquan Li, Ye Chen
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Biomimetics
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Online Access:https://www.mdpi.com/2313-7673/10/3/148
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author Yihan Wang
Yumeng Cai
Bin Xie
Chi Zhu
Yunquan Li
Ye Chen
author_facet Yihan Wang
Yumeng Cai
Bin Xie
Chi Zhu
Yunquan Li
Ye Chen
author_sort Yihan Wang
collection DOAJ
description Due to its exceptional terrain mobility, quadrupedal locomotion has been used in the design of many amphibious robots for broad applications including resource exploration, disaster rescue, and reconnaissance. In this work, swimming of a quadrupedal paddling model is considered, and the effects of the legs’ initial swing angle, swing amplitude, and power phase duration are numerically investigated through three paddling gaits, namely, the trotting gait, the diagonal, and the lateral sequence gaits. Three different modes for drag-based thrust generation, the “Trotting Mode”, the “Hindering Mode”, and the “Separate Mode”, are identified. In the “Trotting Mode”, each pair of diagonal legs contributes equally and alternately to the thrust within the paddling cycle, and its contribution is impaired by the other pair of diagonal legs. In the “Hindering Mode”, the thrust contribution of an individual leg is significantly undermined by the drag resulting from the preceding leg leaving its current power phase and entering the following recovery phase. In the “Separate Mode”, the four legs independently contribute to the total thrust by forming a compact four-peak waveform equally distributed within one paddling cycle. At a given swing amplitude, the leg configuration at peak thrust moment is identical, regardless of initial swing angle and power phase ratio. Meanwhile, a forward-tilted leg configuration with flatter upper- and lower-limb alignment at peak thrust moment consistently indicates a lower thrust generation. Hydrodynamic moments in the diagonal and lateral sequence gaits are much larger than those in the trotting gait. In addition, enhanced thrust is typically accompanied by larger hydrodynamic moments and a higher energy expenditure.
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spelling doaj-art-15cf96a4d8cb43e8bb783c89da93f0972025-08-20T03:43:21ZengMDPI AGBiomimetics2313-76732025-02-0110314810.3390/biomimetics10030148A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal PaddlingYihan Wang0Yumeng Cai1Bin Xie2Chi Zhu3Yunquan Li4Ye Chen5Shien-Ming Wu School of Intelligent Engineering, South China University of Technology, Guangzhou 510641, ChinaShien-Ming Wu School of Intelligent Engineering, South China University of Technology, Guangzhou 510641, ChinaShien-Ming Wu School of Intelligent Engineering, South China University of Technology, Guangzhou 510641, ChinaDepartment of Mechanics and Engineering Science, Peking University, Beijing 100871, ChinaShien-Ming Wu School of Intelligent Engineering, South China University of Technology, Guangzhou 510641, ChinaShien-Ming Wu School of Intelligent Engineering, South China University of Technology, Guangzhou 510641, ChinaDue to its exceptional terrain mobility, quadrupedal locomotion has been used in the design of many amphibious robots for broad applications including resource exploration, disaster rescue, and reconnaissance. In this work, swimming of a quadrupedal paddling model is considered, and the effects of the legs’ initial swing angle, swing amplitude, and power phase duration are numerically investigated through three paddling gaits, namely, the trotting gait, the diagonal, and the lateral sequence gaits. Three different modes for drag-based thrust generation, the “Trotting Mode”, the “Hindering Mode”, and the “Separate Mode”, are identified. In the “Trotting Mode”, each pair of diagonal legs contributes equally and alternately to the thrust within the paddling cycle, and its contribution is impaired by the other pair of diagonal legs. In the “Hindering Mode”, the thrust contribution of an individual leg is significantly undermined by the drag resulting from the preceding leg leaving its current power phase and entering the following recovery phase. In the “Separate Mode”, the four legs independently contribute to the total thrust by forming a compact four-peak waveform equally distributed within one paddling cycle. At a given swing amplitude, the leg configuration at peak thrust moment is identical, regardless of initial swing angle and power phase ratio. Meanwhile, a forward-tilted leg configuration with flatter upper- and lower-limb alignment at peak thrust moment consistently indicates a lower thrust generation. Hydrodynamic moments in the diagonal and lateral sequence gaits are much larger than those in the trotting gait. In addition, enhanced thrust is typically accompanied by larger hydrodynamic moments and a higher energy expenditure.https://www.mdpi.com/2313-7673/10/3/148quadrupedal paddlingthrust generationimmersed-boundary method
spellingShingle Yihan Wang
Yumeng Cai
Bin Xie
Chi Zhu
Yunquan Li
Ye Chen
A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
Biomimetics
quadrupedal paddling
thrust generation
immersed-boundary method
title A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
title_full A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
title_fullStr A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
title_full_unstemmed A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
title_short A Computational Study on the Hydrodynamics of Bio-Inspired Quadrupedal Paddling
title_sort computational study on the hydrodynamics of bio inspired quadrupedal paddling
topic quadrupedal paddling
thrust generation
immersed-boundary method
url https://www.mdpi.com/2313-7673/10/3/148
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