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arXiv 2023年

作者： Dinkel, Holly Di, Julia Santos, Jamie Albee, Keenan Borges, Paulo Moreira, Marina Alexandrov, Oleg Coltin, Brian Smith, Trey Department of Aerospace Engineering The University of Illinois Urbana-Champaign UrbanaIL United States Department of Mechanical Engineering Stanford University StanfordCA United States Department of Physics Chalmers University of Technology Gothenburg Sweden Maritime and Multi-Agent Autonomy Group The Jet Propulsion Laboratory California Institute of Technology PasadenaCA United States Robotics and Autonomous Systems Group CSIRO Data61 BrisbaneQLD Australia Intelligent Robotics Group The NASA Ames Research Center Moffett FieldCA United States

Assistive free-flyer robots autonomously caring for future crewed outposts—such as NASA’s Astrobee robots on the International Space Station (ISS)—must be able to detect day-to-day interior changes to track inventory, detect and diagnose faults, and monitor the outpost status. This work presents a framework for multi-agent cooperative mapping and change detection to enable robotic maintenance of space outposts. One agent is used to reconstruct a 3D model of the environment from sequences of images and corresponding depth information. Another agent is used to periodically scan the environment for inconsistencies against the 3D model. Change detection is validated after completing the surveys using real image and pose data collected by Astrobee robots in a ground testing environment and from microgravity aboard the ISS. This work outlines the objectives, requirements, and algorithmic modules for the multi-agent reconstruction system, including recommendations for its use by assistive free-flyers aboard future microgravity outposts. © 2023, CC BY.

关键词： Space stations

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Sound absorption characteristics of balsa cored asymmetric sandwich composite material

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AIP Conference Proceedings 2024年第1期3178卷

作者： Prahlad Kumar K. Priya Ajit Nandan Kumar Jha Raju Kumar Thakur Vikram Department of Mechanical Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Jharkhand 826004 India Department of Automation & Robotics Sandip Institute of Technology & Research Centre (SITRC) Nashik Maharashtra India

This paper presents acoustical properties of balsa core sandwich panels. The sandwich panel is composed of glass fiber, carbon fiber, and balsa wood. The acoustical properties of the panel is evaluated in terms of absorption coefficient. The impedance tube technique utilizing ASTM Two-Load method is used for the sound absorption and characteristics. Different samples of the sandwich panel are prepared by varying the thickness of core. The sound absorption characteristics is observed to be sensitive to the thickness of samples and direction of incidence of sound waves. Along with the core thickness effect, the effect of placing samples in the direction of sound incidence is also studied. The placement direction is also observed to have a strong influence on the sound absorption. The thinner core sandwich panel has higher sound absorption in case the sample faces the sound source from the carbon fiber side. Whereas thicker core sandwich panel has higher absorption in case of the sample facing the sound source from the glass fiber side.

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Design Optimization and Data-driven Shallow Learning for Dynamic Modeling of a Smart Segmented Electroadhesive Clutch

Design Optimization and Data-driven Shallow Learning for Dyn...

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IEEE International Conference on robotics and automation (ICRA)

作者： Navid Feizi Zahra Bahrami S. Farokh Atashzar Mehrdad R. Kermani Rajni V. Patel Canadian Surgical Technologies and Advanced Robotics (CSTAR) Lawson Health Research Institute London ON Canada School of Biomedical Engineering Western University London ON Canada Institute of Geography University of Erlangen-Nuremberg Erlangen Germany Department of Mechanical and Aerospace Engineering the Department of Electrical and Computer Engineering and the Department of Biomedical Engineering New York University (NYU) New York NY USA NYU WIRELESS and NYU CUSP Department of Electrical and Computer Engineering Western University London ON Canada Department of Electrical and Computer Engineering the Department of Surgery and the Department of Clinical Neurological Sciences School of Biomedical Engineering Western University London ON Canada

Electroadhesive clutches have attracted a great deal of interest in the last decade as semi-active actuators for human-robot interaction due to their lightweight, low power consumption, and tunable high-torque output capability. However, because of the complexity of their dynamics, in most cases, they are utilized in an ON/OFF -control strategy. In this regard, the non-autonomous (time-dependent) degradation of electroadhesive behavior is an inherent challenge that injects unpredictability and uncertainty into the behavior of this family of semi-active clutches. We propose a novel approach to preventing degradation of electroadhesion using a segmented electrode design that modulates the electrical field on the dielectric surface while using a direct current signal and securing low power consumption. This paper, for the first time, presents an optimization process based on a novel analytic model of the proposed actuator. It also develops a data-driven model augmentation using a hybrid shallow learning approach composed of a long short-term memory (LSTM) architecture which is combined with the analytical model. The performance of the proposed semi-active clutch and the data-driven hybrid model is experimentally validated in this paper.

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Robust longitudinal attitude control of flapping-wing micro air vehicle based on disturbance observer

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Journal of institute of Control, robotics and Systems 2019年第11期25卷 1000-1006页

作者： Lee, Jonggu Ryu, Seungwan Kim, H. Jin Department of Mechanical and Aerospace Engineering Seoul National University Korea Republic of Automation and Systems Research Institute Seoul National University Korea Republic of

Flapping-wing micro air vehicles (FWMAVs) are interesting flight platforms due to their energy efficiency, camouflage ability and agility. However, these FWMAVs produce limited forces and moments due to their small scale and complex dynamics, so most studies have been conducted in indoor environments where external disturbance is excluded. In order for these bio-inspired robots to perform various tasks in outside, an ability to react robustly to external disturbance is essential. In this paper, we employ a robust controller called disturbance observer for attitude control of a FWMAV. Before designing a controller, we derive the attitude dynamics of the FWMAV based on experimental data. Then, we validate the proposed algorithm with a flight experiment in a laboratory condition with wind disturbance similar to outdoor flight. © 2019, institute of Control, robotics and Systems. All rights reserved.

关键词： Robust control

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Seed-assisted hydrothermal growth of monoclinic copper oxide nanostructures on carbon fiber fabric for hierarchical composites

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AIP Conference Proceedings 2024年第1期3178卷

作者： Ravi Shankar Rai Payal Senapaty Alok Kumar Vivek Bajpai Department of Automation and Robotics Sandip Institute of Technology and Research Centre Nashik Maharashtra India Department of Mechanical Engineering SRM Institute of Science and Technology Chennai Tamil Nadu India Department of Mechanical Engineering Indian Institute of Technology Jodhpur Rajasthan India Department of Mechanical Engineering Indian Institute of Technology (Indian School of Mines) Dhanbad Jharkhand India

The processing and morphological examination of copper oxide (CuO) nanostructures under varied concentrations and processing temperatures were explored in this research. A two-step seed-assisted hydrothermal approach was used to fabricate CuO nanostructures embedded in the surface of plain-woven carbon fiber fabric (WCF), with seeding followed by growth treatments with controlled chemical precursors. Three major factors are taken in the experimentation such as seed cycles, growth solution, and hydrothermal duration. By adjusting the CuO molar concentrations and controlling the growth temperature in the hydrothermal processing for different set of durations, several nanostructure morphologies of CuO such as petal-like, cuboid-like, buds-like nanorods, and nanoflakes were formed. The field emission scanning electron microscope (FESEM) and Energy-dispersive X-ray spectroscopy (EDS) spectra were used to evaluate diverse morphologies and their elemental compositions. It was discovered that the length of the growth treatment and the number of seeding treatments had a significant impact on the growth of nanostructures. The notion of growing CuO nanostructures directly onto WCF to increase the interfacial parameter of plain carbon fiber polymer composites was proposed in this study, which is a better strategy for secondary reinforcement than adding carbon nanotubes (CNTs) into the matrix. For the construction of laminated hybrid composites using the vacuum assisted resin transfer molding process (VARTM), Epoxy resin was utilized as the matrix material, which was reinforced with generated CuO nanostructures on WCF. The contact surface area between the molecules of the carbon fibers increases due to bonding of nanostructures at the interfaces thus, the load transmission will also increase. This may be responsible for the enhancement in the strength and delamination property of the resulting composite material.

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The effects of small fibre misalignment on the mechanical properties of GFRP laminates: An experimental assessment

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AIP Conference Proceedings 2024年第1期3178卷

作者： Suleiman Lawal Daura Shubham Kalyan Kumar Singh Md. Tauhid Alam Ansari Raju Kumar Thakur Anand Gaurav R. Sankar Department of Mechanical Engineering SRM University Delhi-NCR Sonepat India 131029 Department of Mechanical Engineering IIT(ISM) Dhanbad India 826004 Department of Automation & Robotics Sandip Institute of Technology & Research Centre (SITRC) Nashik Maharashtra India

FRP laminated composites possess properties that greatly depend upon the fiber orientations and interactions between the participating materials. This work studies the effects of fiber misalignment on the mechanical properties of GFRP composites and the misalignments were increased in the steps of 5° to get a brief overview of the failure mechanisms upon their variations. It was observed that a change of 5°, 10°, 15° and 20° in the fiber orientations decreases the ultimate strength of the laminates by about 10, 33, 42 and 52% respectively. While the strain to failure increased by around 10, 39, 85 and 100% respectively compared to the (0°/90°, control samples) on-axis laminate. The increase in fibre orientations also changed the damage development in the samples from a well spread one (for control samples) to more localized one (mostly in the fibre direction) for the laminates with proposed misalignments. High cycle fatigue tests revealed S-N (load vs number of cycles to failure) curve that presented the best endurance limit for the on-axis samples, while plotting the similar results in terms of s-N (normalized load (σmax/σmax) vs number of cycles to failure) indicated ±10° laminates with the most gradual slope.

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Machine-learned flow estimation with sparse data — exemplified for the rooftop of an unmanned aerial vehicle vertiport

arXiv

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arXiv 2024年

作者： Hou, Chang Marra, Luigi Cornejo Maceda, Guy Y. Jiang, Peng Chen, Jingguo Liu, Yutong Hu, Gang Chen, Jialong Ianiro, Andrea Discetti, Stefano Meilán-Vila, Andrea Noack, Bernd R. Chair of Artificial Intelligence and Aerodynamics School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China Department of Aerospace Engineering Universidad Carlos III de Madrid Av. de la Universidad 30 Leganés Madrid28911 Spain Lab School of Civil and Environmental Engineering Harbin Institute of Technology Shenzhen518055 China Guangdong Provincial Key Laboratory of Intelligent and Resilient Structures for Civil Engineering Harbin Institute of Technology Shenzhen518055 China Meituan Technology Co. Ltd Shenzhen518131 China Department of Statistics Universidad Carlos III de Madrid Av. de la Universidad 30 Leganés Madrid28911 Spain Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics Harbin Institute of Technology Shenzhen518055 China

We propose a physics-informed data-driven framework for urban wind estimation. This framework validates and incorporates the Reynolds number independence for flows under various working conditions, thus allowing the extrapolation for wind conditions far beyond the training data. Another key enabler is a machine-learned non-dimensionalized manifold from snapshot data. The velocity field is modeled using a double encoder-decoder approach. The first encoder normalizes data using the oncoming wind speed, while the second encoder projects this normalized data onto the isometric feature mapping manifold. The decoders reverse this process, with k-nearest neighbor performing the first decoding and the second undoing the normalization. The manifold is coarse-grained by clustering to reduce the computational load for de- and encoding. The sensor-based flow estimation is based on the estimate of the oncoming wind speed and a mapping from sensor signal to the manifold latent variables. The proposed machine-learned flow estimation framework is exemplified for the flow above an Unmanned Aerial Vehicle vertiport. The wind estimation is shown to generalize well for rare wind conditions, not included in the original database. © 2024, CC BY.

关键词： Reynolds number

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Integrated Behavior Planning and Motion Control for Autonomous Vehicles with Traffic Rules Compliance

Integrated Behavior Planning and Motion Control for Autonomo...

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IEEE International Conference on robotics and Biomimetics

作者： Haichao Liu Kai Chen Yulin Li Zhenmin Huang Jianghua Duan Jun Ma Robotics and Autonomous Systems Thrust The Hong Kong University of Science and Technology (Guangzhou) Guangzhou China Division of Emerging Interdisciplinary Areas The Hong Kong University of Science and Technology Hong Kong SAR China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and Technology Hong Kong SAR China HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Shenzhen China

In this article, we propose an optimization-based integrated behavior planning and motion control scheme, which is an interpretable and adaptable urban autonomous driving solution that complies with complex traffic rules while ensuring driving safety. Inherently, to ensure compliance with traffic rules, an innovative design of potential functions (PFs) is presented to characterize various traffic rules related to traffic lights, traversable and non-traversable traffic line markings, etc. These PFs are further incorporated as part of the model predictive control (MPC) formulation. In this sense, high-level behavior planning is attained implicitly along with motion control as an integrated architecture, facilitating flexible maneuvers with safety guarantees. Due to the well-designed objective function of the MPC scheme, our integrated behavior planning and motion control scheme is competent for various urban driving scenarios and able to generate versatile behaviors, such as overtaking with adaptive cruise control, turning in the intersection, and merging in and out of the roundabout. As demonstrated from a series of simulations with challenging scenarios in CARLA, it is noteworthy that the proposed framework admits real-time performance and high generalizability.

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System Parameter Identification for a Quadrotor UAV by Frequency Domain Method

System Parameter Identification for a Quadrotor UAV by Frequ...

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2021 China automation Congress, CAC 2021

作者： Huang, Jing Li, Dong Wang, Ban Zhang, Youmin Mu, Lingxia Jiao, Shangbin Liu, Han Department of Automation and Information Engineering Xi'an University of Technology Shaanxi Xi'an710048 China Jiujiang Precision Test Technology Research Institute Jiangxi Jiujiang332000 China School of Aeronautics Northwestern Polytechnical University Shaanxi Xi'an710072 China Department of Mechanical Industrial and Aerospace Engineering Concordia University MontrealQCH3G 1M8 Canada

ISBN: (纸本)9781665426473

Without runways and the complex "cross swash plate" mechanical device, quadrotor can both take off vertically and achieve fast maneuvers. As a quite unstable and under-actuated system, to get an accurate bare-airframe model of the studied quadrotor is the key for flight control design. In this paper, the frequency domain system parameter identification method is utilized to obtain the state-space model of a quadrotor. Firstly, the theoretical analysis is conducted to acquire the nonlinear model for the quadrotor. Then, the nonlinear model is linearized, which is divided into four categories by different basic motions as: roll-axis, pitch-axis, yaw-axis, and altitude. After that, CIFER® is chosen to identify the parameters of four categories. Finally, with the low value of the Cramer-Rao (CR) bounds below 20%, it is concluded that the frequency response of the identified model can fit in the real flight data very well, and an accurate bare-airframe model is obtained. © 2021 IEEE

关键词： Frequency response

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Topologically assisted optimization for rotor design

arXiv

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arXiv 2023年

作者： Wang, Tianyu Yang, Yannian Chen, Xuanwu Li, Pengyu Iollo, Angelo Maceda, Guy Cornejo Y. Noack, Bernd R. School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China Key Laboratory of Autonomous Systems and Networked Control Ministry of Education Unmanned Aerial Vehicle Systems Engineering Technology Research Center of Guangdong School of Automation Science and Engineering South China University of Technology Guangzhou510640 China Institute of Aero Engine Tsinghua University Beijing10084 China Department of Mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen518055 China Institut de Mathématiques de Bordeaux Université de Bordeaux and Memphis Team Centre Inria de l’Université de Bordeaux Talence33400 France

We develop and apply a novel shape optimization exemplified for a two-blade rotor with respect to the figure of merit (FM). This topologically assisted optimization (TAO) contains two steps. First a global evolutionary optimization is performed for the shape parameters and then a topological analysis reveals the local and global extrema of the objective function directly from the data. This non-dimensional objective function compares the achieved thrust with the required torque. Rotor blades have a decisive contribution to the performance of quadcopters. A two-blade rotor with pre-defined chord length distribution is chosen as the baseline model. The simulation is performed in a moving reference frame with a k−ω turbulence model for the hovering condition. The rotor shape is parameterized by the twist angle distribution. The optimization of this distribution employs a genetic algorithm. The local maxima are distilled from the data using a novel topological analysis inspired by discrete scalar-field topology. We identify one global maximum to be located in the interior of the data and five further local maxima related to errors from non-converged simulations. The interior location of the global optimum suggests that small improvements can be gained from further optimization. The local maxima have a small persistence, i.e., disappear under a small Ε perturbation of the figure of merit values. In other words, the data may be approximated by a smooth mono-modal surrogate model. Thus, the topological data analysis provides valuable insights for optimization and surrogate modeling. Copyright © 2023, The Authors. All rights reserved.

关键词： Turbulence models

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