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A Phase-change-material-based Variable Stiffness Sheath Inspired by a Multi-layer Wave Spring Structure for Flexible Upper Gastrointestinal Endoscopic Robots

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IEEE robotics and Automation Letters 2025年第6期10卷 6504-6511页

作者： Song, Dezhi Luo, Xiangyu Yu, Xiangyang Zhang, Bo Yang, Zhengbao Hu, Chengzhi Shi, Chaoyang Tianjin University Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education School of Mechanical Engineering Tianjin300072 China Tianjin Hospital of ITCWM Tianjin Nankai Hospital Department of Gastrointestinal Surgery Tianjin300100 China Waseda University Future Robotics Organization Tokyo1620044 Japan The Hong Kong University of Science and Technology Department of Mechanical and Aerospace Engineering Hong Kong Southern University of Science and Technology Department of Mechanical and Energy Engineering Shenzhen518055 China

Continuum robots in flexible gastrointestinal endoscopy require transitioning between flexible and rigid states. Phase-change-material-based variable stiffness (VS) methods exhibit a significant stiffness change ratio but are typically time-consuming. These materials are commonly fabricated as simple cylindrical or tubular structures and integrated with continuum joints, overlooking how the VS module's structural characteristics affect stiffness modulation and bending performance. To balance motion flexibility and operational stability, this work presents a stiffness-tunable sheath inspired by a multi-layer wave spring structure, fabricated utilizing thermoplastic material. A water-based active heating/cooling method is employed, wherein the circulation of hot/cold water through silicone tubes helically wrapped around the VS sheath enables rapid thermal regulation. Structural parameters selection of the VS sheath based on the orthogonal design method has been performed to enhance rigid-state stiffness and reduce maximum stress during 90° flexion in a flexible state. Experimental results showed the proposed VS sheath achieves a stiffness change ratio of up to 16.5 times within 30s. After being integrated with a continuum joint, the sheath demonstrates an average positioning error of 1.48mm within a ±90° bending range in a flexible state, without structural compromise or interference with the continuum joint's bending. In a rigid state, the proposed design can resist 400g external payload with a deflection of less than 6mm. The efficacy of this design has been validated through ex-vivo experiments on a porcine stomach. © 2016 IEEE.

关键词： Endoscopy

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Analysis of VSC-HVDC System in the Asynchronously Operating Grids During AC Line Faults 1

Analysis of VSC-HVDC System in the Asynchronously Operating ...

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1st IEEE International Conference on Smart and Sustainable Developments in Electrical engineering, SSDEE 2025

作者： Tiwari, Ravi Shankar Sinha, Ashish Kumar Kumar, Prashant GLA University Department of Electrical Engineering Mathura India Dongguk University Department of Mechanical Robotics and Energy Engineering Seoul04620 Korea Republic of

ISBN: (纸本)9798331542108

The growing energy demand and ruler electrification accelerates the integration of synchronously and asynchronously operating grids. Generation based on hydro, wind or solar may operate at a frequency slightly different than the national grid due to its intermittent nature and operational constraints. It is important to integrate the generation of various sources to improve grid reliability. Wind energy farms are usually integrated into the grid using VSC (voltage source converters)-HVDC systems. Faults on either side of the HVDC link may create operational and stability issues for interconnecting the HVDC link. The fault ride-through is the ability of the VSC-HVDC system to remain connected with the grid during faults. This paper explores and analyzes the fault ride-through ability of a± 100kV, 200 MW two-level VSC-HVDC to maintain interconnections between grids, especially during the presence of intermittent sources like wind farms at one end of the VSC-HVDC system. © 2025 IEEE.

关键词： Electric power transmission networks

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Manufacturing process design for cellular structure used as impact energy absorbers 4

Manufacturing process design for cellular structure used as ...

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4th International Symposium on Advances and Innovation in mechanical engineering, ISAIME 2023

作者： Komara, Asep Indra Setiawan, Rachman Budiwantoro, Bagus Doctoral Program of Mechanical Engineering Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Bandung Indonesia Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Bandung Indonesia Manufacturing Design Engineering Department Politeknik Manufaktur Bandung Bandung Indonesia

The application of passive safety technology in vehicles is generally through impact-absorbing structures. This technology has been widely applied to trains, planes, and cars to protect passengers from fatal accidents. Cellular structures are defined by a unit cell that combines material, space, and unit cell repetition to obtain a large structure. It is selected as the base structure of the impact energy absorber for its potentially high specific energy absorption (SEA]. Such a structure poses a challenge in its manufacturing method. This study examines alternative manufacturing processes for cellular structures designed as impact absorbers, and then selects and develops an effective and efficient manufacturing method to produce these cellular structures. Several alternative manufacturing methods were chosen to exercise the use of a combined plaster molding technology and additive manufacturing for prototyping. Manufacturing process simulation studies were conducted using Altair Inspire Cast software to determine the success of the casting process. The final stage is to carry out the process of making cell structures and evaluating the results. This work results in an effective manufacturing process design to be implemented throughout the production stage. Furthermore, for mass production, mold patterns may be replaced by using injection molding. © 2025 Institute of Physics Publishing. All rights reserved.

关键词： Injection molding

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The Influence of Silicon Dioxide as a Fuel Additive in a Diesel Engine Fuelled by Pure Palm Oil 4

The Influence of Silicon Dioxide as a Fuel Additive in a Die...

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4th International Symposium on Advances and Innovation in mechanical engineering, ISAIME 2023

作者： Prahmana, Rico Aditia Darmanto, Prihadi Setyo Reksowardojo, Iman Kartolaksono Prakoso, Tirto Juangsa, Firman Bagja Doctoral Program of Mechanical Engineering Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Bandung40132 Indonesia Program Study of Mechanical Engineering Faculty of Industrial Technology Institut Teknologi Sumatera South Lampung35365 Indonesia Thermal Science and Engineering Research Group Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Bandung Indonesia Department of Chemical Engineering Faculty of Industrial Technology Institut Teknologi Bandung Bandung40132 Indonesia Program Study of Mechanical Engineering Faculty of Industrial Technology Universitas Pertamina Jakarta12220 Indonesia

In the last decade, the Indonesian government has implemented a program to use biodiesel as a substitute for fossil diesel to reduce dependence on fossil fuels. On the other hand, the development of biodiesel as an alternative fuel to replace fossil diesel has several challenges, one of which is the production of biodiesel, which is more complicated and requires a long process. However, the direct use of crude palm oil (CPO) in diesel engines is not recommended because it has many drawbacks. Research recently shows that fuel additives in diesel engines have promising prospects. Therefore, to solve the problem, this study used pure palm oil (PPaO) as the primary fuel, with the addition of silicon oxide (SiO2) as a fuel additive in diesel engines. The results showed that using SiO2 additive in PPaO can increase thermal efficiency by 18.8% at 60% load compared to diesel fuel (DF). Nevertheless, using this fuel increased specific fuel consumption (SFC) by 3.9% on average and increased the opacity by 153% compared to diesel fuel. These results indicate that SiO2 has the potential to be developed as an effective additive to PPaO fuel that can improve the efficiency and performance of diesel engines. © 2025 Institute of Physics Publishing. All rights reserved.

关键词： Biodiesel

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Distribution-Allowed Noise-Resistant Neural Dynamics for Constrained Time-Dependent Quadratic programming With kWTA Application

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IEEE Transactions on Systems, Man, and Cybernetics: Systems 2025年第5期55卷 3732-3741页

作者： Ma, Xin Ma, Dexiu Liu, Mei The Chinese University of Hong Kong Multi-Scale Medical Robotics Center Department of Mechanical and Automation Engineering Hong Kong Dingxi Vocational and Technical College School of Electronic Information Dingxi730500 China

Existing computational models for addressing time-dependent quadratic programming (TDQP) problems encounter some challenges, such as generating lagging errors, lack of noise immunity, and inability to be distributed. To handle these challenges, this article proposes a distribution-allowed noise-resistant neural dynamics (DANRND) model to solve TDQP problems with equality and inequality constraints by introducing auxiliary variables rather than by using the nonlinear complementary problem (NCP) function. The proposed model is able to effectively eliminate the hysteresis error and suppress the influence of noises. Specifically, the proposed model is capable of implementation in a distributed manner, which extends its scope of applications. Then, theoretical analyses are provided to prove the global convergence in both noise-free and noisy conditions. Simulative examples and comparison results with existing methods are offered, demonstrating the superiority of the proposed DANRND model. Finally, a distributed cooperative task based on the k-winner-take-all (kWTA) operation is performed on a multirobot platform to further verify the distributed implementation of the proposed DANRND model. © 2013 IEEE.

关键词： Quadratic programming

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Low-cost chemical surface smoothing of CO2 laser-etched acrylic using WELD ON 4 acrylic solvent cement

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International Journal of Advanced Manufacturing Technology 2025年第5期138卷 2245-2255页

作者： Moncada, Luis H. Safaripour, Samira Hutter, Tanya Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States Materials Science and Engineering Program and Texas Materials Institute The University of Texas at Austin AustinTX78712 United States

With the increasing use of micro-manufactured devices and the demand for low-cost fabrication techniques, this study presents a simple and scalable surface polishing method for laser etched acrylic using WELD-ON 4 acrylic solvent cement, a solvent typically used for bonding thermoplastics. The method’s effectiveness was evaluated by treating acrylic samples up to three times and analyzing changes in transparency, surface roughness average (Ra), luminescence, and wettability. Results show that even a single treatment significantly improved surface smoothness, reduced light scattering, and brought contact angle and optical clarity closer to those of unetched acrylic. After three treatments, the surface became isotropic, with laser-etched lines disappearing. Specifically, a 60% reduction in Ra was observed in the direction perpendicular to the etched lines, while the parallel direction initially showed a similar trend, followed by a slight increase attributed to the formation of surface irregularities caused by the re-solidification of dissolved acrylic. Contact angle measurements indicated that the surface remained hydrophilic, with controllable wettability based on the number of treatments. Overall, this method provides a low-cost, cleanroom-free solution for improving the surface finish of laser-fabricated acrylic components. Its compatibility with complex or recessed geometries makes it particularly suitable for microfluidic devices and other precision applications requiring both optical clarity and controlled surface properties. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2025.

关键词： Carbon dioxide lasers

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Analysis of Sandwich Structures with 3D-Printed Kresling Origami Cores

Analysis of Sandwich Structures with 3D-Printed Kresling Ori...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Hossain, Md Shahjahan Csercsevits, Vincent Seshaiah, Kira Bateniparvar, Omid Ghosh, Ranajay Department of Mechanical and Aerospace Engineering University of Central Florida OrlandoFL United States Department of Mechanical Engineering Widener University ChesterPA United States Smith College Picker Engineering Program NorthamptonMA United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Lightweight structures with bioinspired metamaterials, with their uniquely engineered properties not found in naturally occurring materials, have garnered significant attention for their potential in various engineering applications. This study explores the mechanical behavior of sandwich plate structures utilizing the Kresling origami pattern, fabricated through a straightforward 3D printing process. By conducting 3-point bending and compression tests, as well as simulations with Abaqus software, the research investigates the distinctive mechanical properties and performance enhancements these origami-inspired structures offer under mechanical loading. This study is noteworthy for being the first to investigate the bending characteristics of sandwich structures utilizing the two cell Kresling pattern or double Kresling, an area that has not been previously explored. Utilizing the Kresling structure in sandwich panels poses a challenge due to its rotational behavior. To address this, we employ a double Kresling pattern, which confines the rotation to the middle layer. This approach ensures that the outer layers remain stable, maintaining the overall integrity of the sandwich panel structure during deformation under mechanical loading. The findings reveal that the 3D-printed Kresling origami core significantly reduces weight while maintaining structural integrity, making it especially beneficial for aerospace engineering, where lightweight yet strong materials are crucial. This research highlights the potential of Kresling-patterned sandwich plates to improve efficiency and performance in supersonic vehicles, providing valuable insights into their structural efficiency and applicability in advanced engineering fields. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Compression testing

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Adaptive Robust Control Integrated With Gaussian Processes for Quadrotors: Enhanced Accuracy, Fault Tolerance and Anti-Disturbance

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IEEE Transactions on Systems, Man, and Cybernetics: Systems 2025年第5期55卷 3235-3248页

作者： Liang, Weisheng Amer, Abdelhakim Mehndiratta, Mohit Chen, Zheng Yao, Bin Kayacan, Erdal Zhejiang University State Key Laboratory of Fluid Power and Mechatronic Systems Hangzhou310027 China Aarhus University Artificial Intelligence in Robotics Laboratory Department of Electrical and Computer Engineering Aarhus8000 Denmark GIM Robotics Espoo02650 Finland Zhejiang University Ocean College Ocean Research Center of Zhoushan Zhoushan316021 China Purdue University School of Mechanical Engineering West Lafayette47907 United States Department of Electrical Engineering and Information Technology Paderborn33098 Germany

With increasingly challenging applications for quadrotors, higher requirements are emerging for tracking accuracy and safety. While high accuracy is a prerequisite for complex tasks, safety is ensured through tolerance to actuator faults and resistance to external disturbances. In this article, adaptive robust control (ARC) integrated with Gaussian processes (GPs), i.e., ARC-GP, is proposed to achieve enhanced accuracy, fault tolerance, and anti-disturbance. These three requirements are interrelated and affected by uncertainties. The primary idea of this article is to categorize uncertainties into parametric and nonparametric types, which are then addressed through parameter adaptation and GP, respectively. First, a detailed dynamic model is established, including actuator models that reflect different types of faults corresponding to changes in different physical parameters. Then, parameter adaptation is designed, with direct and indirect methods adopted for different parameters. In particular, the actuator parameters are effectively estimated to achieve targeted fault compensation. Regarding GP for nonparametric uncertainties, its model parameters are also updated via parameter adaptation. The GP thereby also learns parameter estimation errors along with external disturbances. Accordingly, ARC controllers are designed, for which robust feedback terms are constructed to further mitigate uncertainties on the basis of the covariances predicted by GP. The experiments demonstrate that the proposed ARC-GP can actively tolerate various types of actuator faults and better resist wind disturbances. © 2013 IEEE.

关键词： Robust control

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Real-Time Adaptation of Deep Learning Walking Speed Estimators Enables Biomimetic Assistance Modulation in an Open-Source Bionic Leg

IEEE Transactions on Medical Robotics and Bionics

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IEEE Transactions on Medical robotics and Bionics 2025年第2期7卷 711-722页

作者： Maldonado-Contreras, Jairo Y. Johnson, Cole Zhou, Sixu Kim, Hanjun Knight, Ian Herrin, Kinsey R. Young, Aaron J. Institute of Robotics and Intelligent Machines Georgia Institute of Technology Mechanical Engineering Department AtlantaGA30332 United States Georgia Institute of Technology School of Computer Science AtlantaGA30332 United States

This study introduces a novel continual learning algorithm that incrementally improves the performance of deep-learning-based walking speed estimators during level-ground walking with a powered knee-ankle prosthesis. While user-dependent (DEP) estimators generally outperform user-independent (IND) estimators, they require the pre-collection of DEP training data. In contrast, our real-time algorithm adapts IND estimators to self-labeled DEP data generated during walking, eliminating the need for pre-collected datasets. The algorithm also features a biomimetic scaling mechanism that adjusts prosthetic assistance based on speed estimates. We evaluated our algorithm on novel subjects (N=10) with unilateral above-knee amputations during treadmill and overground walking. For treadmill trials, when adapted with estimated and ground truth labels, estimators achieved mean absolute errors (MAEs) of 0.074 [0.023] (mean, [standard deviation]) and 0.074 [0.018] m/s, respectively, reflecting a significant 28% (p ¡ 0.05) reduction in MAE compared to non-adapted estimators. For overground trials, treadmill-adapted estimators demonstrated a significant 18% (p ¡ 0.05) reduction in MAE compared to non-adapted estimators. Our algorithm significantly reduced speed estimation errors within one minute of walking and delivered biomimetic assistance (r{=}0.91) across speeds. This approach allows off-the-shelf powered prostheses to seamlessly adapt to new users, delivering biomimetic assistance through precise, real-time walking speed estimation. © 2018 IEEE.

关键词： Knee prostheses

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Eutectic conditions of carbon dioxide clathrate hydrate and sodium Chloride: Implications for zero liquid discharge seawater desalination

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Journal of Industrial and engineering Chemistry 2025年 147卷 512-521页

作者： Gibo, Akari Nakao, Seiya Ohmura, Ryo Yasuda, Keita Energy and Environment Program School of Engineering University of the Ryukyus 1 Senbaru Okinawa Nishihara903-0213 Japan Department of Mechanical Engineering Keio University 3-14-1 Hiyoshi Kohoku-ku Yokohama223-8522 Japan

The eutectic temperature, pressure, and concentration conditions of carbon dioxide clathrate hydrate and sodium chloride dihydrate were measured to advance clathrate hydrate-based seawater desalination and salt production technology that enables seawater desalination through zero liquid discharge. The measured eutectic conditions were within the temperature range of 256.2 K ≤ Teu ≤ 263.5 K, the pressure range of 0.91 MPa ≤ peu ≤ 2.70 MPa, and the concentration range, expressed as the mass fraction of sodium chloride, of 0.235 ≤ wm,eu ≤ 0.242. These eutectic conditions correspond to the four-phase equilibrium of a saturated sodium chloride aqueous solution, carbon dioxide clathrate hydrate, carbon dioxide gas, and sodium chloride dihydrate, as well as the five-phase equilibrium of a saturated sodium chloride aqueous solution, carbon dioxide clathrate hydrate, carbon dioxide gas, liquid carbon dioxide, and sodium chloride dihydrate. Based on the measured eutectic conditions, implications for implementing clathrate hydrate-based seawater desalination and salt production were presented, including a conceptual design for a methodology involving reverse osmosis, multi-stage clathrate hydrate-based seawater desalination, and clathrate hydrate-based seawater desalination and salt production. © 2024 The Korean Society of Industrial and engineering Chemistry

关键词： Sodium chloride

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