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Compressive and energy absorption properties of titanium hybrid lattice structures for bioimplant applications fabricated via LPBF

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Materials and Design 2025年 254卷

作者： Karmiris-Obratański, Panagiotis Georgakopoulos-Soares, Ilias Cichocki, Kamil Lisiecka-Graca, Paulina Papazoglou, Emmanouil L. Advanced Manufacturing Laboratory Department of Manufacturing Systems Faculty of Mechanical Engineering and Robotics AGH University of Krakow Krakow Poland School of Chemical Engineering Department of Materials Science and Engineering National Technical University of Athens Heroon Polytechniou 9 Athens15780 Greece Institute for Personalized Medicine Department of Biochemistry and Molecular Biology The Pennsylvania State University College of Medicine HersheyPA United States Faculty of Metals Engineering and Computer Science AGH University of Krakow Adama Mickiewicza Ave. 30 Kraków30-059 Poland School of Mechanical Engineering Section of Manufacturing Technology National Technical University of Athens Heroon Polytechniou 9 Athens15780 Greece

The compressive properties of lattice structures are strongly influenced by lattice design, density, material, and manufacturing method. Recent advancements in manufacturing, particularly Additive Manufacturing, have enabled the fabrication of complex lattice structures from advanced materials. Building on this progress, the present study investigates the compressive properties and energy absorption capabilities of four distinct lattice structures at three relative densities (20 %, 30 %, and 40 %), specifically tailored for implant applications. The lattices, fabricated from Ti6Al4V ELI alloy using the Laser Powder Bed Fusion (LPBF) method, include a hybrid Fluorite-BCC lattice, a SplitP TPMS skeletal lattice, a stochastic Voronoi lattice, and a hybrid Voronoi-TPMS Gyroid lattice. Compressive properties, including the Elastic Modulus of Compression (EMC), Compressive Yield Strength, and Ultimate Compressive Strength, were systematically analyzed alongside energy absorption capabilities. The Gibson-Ashby model was employed to quantify the relationship between compressive properties and relative density. Additionally, Digital Image Correlation and high-resolution imaging during compression tests provided detailed insights into deformation mechanisms and collapse behavior. The findings offer valuable insights into the compressive performance of these novel hybrid lattices, highlighting their potential applicability in bioimplant applications, with the Fluorite-BCC lattice exhibits the highest EMC and the Fluorite-BCC and SplitP lattices exhibit higher energy absorption capabilities. © 2025 The Author(s)

关键词： Machinability

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The MEDUSA class of autonomous marine vehicles and their role in EU projects

The MEDUSA class of autonomous marine vehicles and their rol...

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OCEANS - Europe

作者： Pedro Caldeira Abreu João Botelho Pedro Góis Antonio Pascoal Jorge Ribeiro Miguel Ribeiro Manuel Rufino Luís Sebastião Henrique Silva Laboratory of Robotics and Systems in Engineering and Science (LARSyS) University of Lisbon Lisbon Portugal

This paper describes a new class of autonomous marine vehicles named Medusa and highlights their role in a number of EU projects addressing multiple vehicle scenarios. The MEDUSA vehicles, with surface and diving versions, were designed and built at the Institute for systems and robotics, IST, Univ. de Lisboa, Portugal as a result of an effort aimed at affording researchers and practitioners of marine robotics tools to: i) assess the efficacy of cooperative motion control and navigation algorithms and ii) seamlessly execute scientific and commercial missions with multiple robots at sea. We first define the problem of designing the MEDUSA-class of vehicles by describing the desired functional requirements that motivated their development and then present our solution. Mechanical and electrical design considerations that relate to the requirements are explained, and the software architecture is described. This includes a brief overview of the navigation system, the main lower-level control loops which other features can build upon, and some of the higher-level algorithms for multiple-vehicle cooperative missions. We also illustrate the functionality of the mission control system, a dedicated software suite that allows operators to seamlessly program and follow the state of execution of cooperative missions involving multiple vehicles, possibly running different operations or missions in parallel. Finally, we summarize the participation of IST and the MEDUSA vehicles in a number of representative EC-funded Marine robotics-related projects.

关键词： Vehicles Navigation Sensors Robots Batteries Payloads Software architecture

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Cooperative Navigation and Control: the EU MORPH project

Cooperative Navigation and Control: the EU MORPH project

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Oceans MTS/IEEE Washington (Conference)

作者： Pedro Caldeira Abreu Mohammadreza Bayat Joao Botelho Pedro Gois Joao Pedro Gomes Antonio Pascoal Jorge Ribeiro Miguel Ribeiro Manuel Rufino Luis Sebastiao Henrique Silva Laboratory of Robotics and Systems in Engineering and Science (LARSyS) ISR/IST University of Lisbon

ISBN: (纸本)9781467393744

The EU MORPH project advances the use of a formation of five autonomous marine vehicles for mapping and scientific surveying of challenging, unstructured underwater environments as a means to overcome the limitations imposed by current single-vehicle based technology. We describe the test scenarios envisioned in the project and the requirements and constraints that they impose on the cooperative navigation and control systems that enable the concerted operation of the vehicle formation. We then provide a high-level description of each of the blocks that compose the final navigation and formation control architecture, developed at ISR/IST. We highlight how the systems take into account specific mission-related requirements and applications (e.g., typical trajectories employed for mapping and surveying). We describe the results of several trials at sea (involving multiple partners in the project and a group of heterogeneous vehicles) that illustrate the applicability of the MORPH concept in real operational scenarios as well as the limitations of the systems developed.

关键词： Autonomous marine vehicles Underwater surveying Formations of autonomous vehicles Cooperative navigation and control

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Real-time Trajectory Generation for Multiple Drones using Bézier Curves ⁎

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IFAC-PapersOnLine 2020年第2期53卷 9276-9281页

作者： Bahareh Sabetghadam Rita Cunha António Pascoal Laboratory of Robotics and Engineering Systems (LARSyS) ISR/IST University of Lisbon Lisbon Portugal

Practical applications of drones are expanding into many new areas due to their fast-evolving technology. Looking further into the future, it is very likely that applications will require more than one drone to tackle a specific task, calling for reliable and efficient algorithms that can generate collision-free trajectories for multiple drones, under timing constraints of real-time applications. In this paper, we study a motion planning method based on the Bézier parametrization of spatial paths with a special focus on the less addressed issue in this method, (inefficient) constraint evaluation, that might hinder its use in real-time trajectory generation for multi-drone applications. We take advantage of the Bézier curves properties to obtain a small-scale optimization problem and find a finite set of inequalities that guarantee constraints satisfaction. We also propose a method to lower the conservatism in the resulting set of inequalities without the need to use unnecessary high-degree Bézier curves. Numerical results illustrate the efficacy of the presented method in reducing the computational costs associated with generating collision-free trajectories for multiple drones and re-planning them online with a receding horizon.

关键词： Trajectory Generation Real-time Bezier Curves

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Multimodal Emotion Classification Supported in the Aggregation of Pre-trained Classification Models 1

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23rd International Conference on Computational science, ICCS 2023

作者： Cardoso, Pedro J. S. Rodrigues, João M. F. Novais, Rui LARSyS – Laboratory for Robotics and Engineering Systems ISR-Lisbon Lisboa1049-001 Portugal Instituto Superior de Engenharia Universidade do Algarve Faro8005-129 Portugal

ISBN: (数字)9783031360305

ISBN: (纸本)9783031360299

Human-centric artificial intelligence struggles to build automated procedures that recognize emotions which can be integrated in artificial systems, such as user interfaces or social robots. In this context, this paper researches on building an Emotion Multi-modal Aggregator (EMmA) that will rely on a collection of open-source single source emotion classification methods aggregated to produce an emotion prediction. Although extendable, tested solution takes a video clip and divides into its frames and audio. Then a collection of primary classifiers are applied to each source and their results are combined in a final classifier utilizing machine learning aggregator techniques. The aggregator techniques that have been put to the test were Random Forest and k-Nearest Neighbors which, with an accuracy of 80%, have demonstrated superior performance over primary classifiers on the selected dataset. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

关键词： Nearest neighbor search

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Cooperative Navigation Based on Bearing and Range Measurements to Different Vehicles

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IFAC-PapersOnLine 2020年第2期53卷 14552-14557页

作者： David Santos Pedro Batista Institute for Systems and Robotics Laboratory for Robotics and Engineering Systems Lisboa Portugal Institute for Systems and Robotics LARSyS Instituto Superior Técnico Universidade de Lisboa Portugal.

This paper presents a navigation solution for a vehicle operating in cooperation with two other. The vehicle is assumed to measure bearing to one of the aiding vehicles and range to the other. An observer with globally exponentially stable error dynamics is designed by obtaining an equivalent observable linear time-varying system using an artificial output and state augmentation. The observer relies on local measurements, as well as limited communication between the vehicles. Simulations are performed to assess the proposed solution.

关键词： Navigation bearing range cooperative navigation Kalman filter

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Cooperative control and navigation in the scope of the EC CADDY project

Cooperative control and navigation in the scope of the EC CA...

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OCEANS - Europe

作者： Pedro Abreu Mohammadreza Bayat João Botelho Pedro Góis António Pascoal Jorge Ribeiro Miguel Ribeiro Manuel Rufino Luís Sebastião Henrique Silva Laboratory of Robotics and Systems in Engineering and Science (LARSyS) ISR/IST University of Lisbon Lisbon Portugal

Cognitive Autonomous Diving Buddy (CADDY) is an FP7 project initiated in February 2014. The key objectives of the project are to develop, implement, and demonstrate in the course of missions at sea the efficacy of a number of innovative systems to assist human divers during the execution of demanding scientific and commercial activities in hazardous underwater environments. At the core of CADDY is the development of an underwater robot that plays the role of a buddy diver and a surface robot to improve guidance, monitoring, assistance, and safety of the diver's mission. The present paper gives a brief summary of the work done during the first year of the project towards the development and testing of the systems required for coordinated surface / underwater vehicle operations. We consider the cases where the leader is either the surface or the underwater vehicle. The architecture adopted for multiple vehicle coordination is described. Results of tests with the MEDUSA class of autonomous marine vehicles show the efficacy of the systems developed for navigation and coordinated motion control.

关键词： Vehicles Underwater vehicles Navigation Trajectory Robot kinematics

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Hierarchical Sponge-Hydrogel Hybrid Structures with Robust Interfaces

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Chinese Journal of Chemistry 2023年第20期41卷 2635-2640页

作者： Pei Zhang Guangda Chen Xingmei Chen Junfei Xing Yue Tao Ji Liu Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhenGuangdong518055 China Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Department of Mechanical and Energy EngineeringSouthern University of Science and TechnologyShenzhenGuangdong518055 China Guangdong Provincial Key Laboratory of Human-Augmentation and Rehabilitation Robotics in Universities Southern University of Science and TechnologyShenzhenGuangdong518055 China

Soft materials including elastomers and hydrogels are playing critical roles in a variety of fields,including bioelectrodes,batteries,supercapacitors,biomedical scaffolds,and solar vapor *** hydrophobic sponges(i.e.,mechanical robustness,elasticity and macroscopic porous structure)and hydrophilic hydrogels(i.e.,autonomous water absorption and transportation,biocompatibility)within one unit could readily combine the complementary characters from each component,making a number of future research directions and applications *** propose a simple yet effective strategy to construct sponge-hydrogel hybrid structures with robust hydrophobic-hydrophilic *** sponge scaffold imparts the sponges-hydrogel hybrids with desirable mechanical robustness,elasticity and macroscopic *** the other hand,the incorporated hydrogel component endows the hybrids with high water content(98 wt%hydrogel and 2 wt%sponge),superior compatibility,and nanoscale pores allowing for storage and transportation of various chemical and biological *** further demonstrate that the introduction of hydrophilic hydrogel components could effectively improve the liquid absorption capability,blood coagulation rate,hemostatic capacity and hemocompatibility,thus promising as hemostatic agents.

关键词： Sponge-hydrogel hybrid Interface Hierarchical Robustness Liquid absorption Gels Polymer Composites Materials science

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A practical PID variable stiffness control and its enhancement for compliant force-tracking interactions with unknown environments

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science China(Technological sciences) 2023年第10期66卷 2882-2896页

作者： ZHANG Xin ZHOU Hao LIU JinGuo JU ZhaoJie LENG YuQuan YANG ChenGuang State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang 110169China University of Chinese Academy of Sciences Beijing 100049China School of Computing University of PortsmouthPortsmouth PO13HEUK Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Department of Mechanical and Energy EngineeringSouthern University of Science and TechnologyShenzhen 518055China Key Laboratory of Autonomous Systems and Networked Control College of Automation Science and EngineeringSouth China University of TechnologyGuangzhou 510640China

Compliant interaction control is a key technology for robots performing contact-rich manipulation *** design of the compliant controller needs to consider the robot hardware because complex control algorithms may not be compatible with the hardware performance,especially for some industrial robots with low bandwidth *** paper focuses on effective and easy-to-use compliant control algorithms for position/velocity-controlled *** by human arm stiffness adaptation behavior,a novel variable target stiffness(NVTS)admittance control strategy is proposed for adaptive force tracking,in which a proportional integral derivative(PID)variable stiffness law is designed to update the stiffness coefficient of the admittance function by the force and position ***,its stability and force-tracking capability are theoretically *** addition,an impact compensator(Impc)is integrated into the NVTS controller to enhance its disturbance-suppression capability when the robot is subjected to strong vibration disturbances in complicated surface polishing *** proposed controllers are validated through four groups of experimental tests using different robots and the corresponding results demonstrate that they have high-accuracy tracking capability and strong adaptability in unknown environments.

关键词： compliant interaction control force tracking PID variable stiffness impact compensator unknown environments

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EFFICIENT DISTANCE COMPUTATION USING BEST ELLIPSOID FIT

EFFICIENT DISTANCE COMPUTATION USING BEST ELLIPSOID FIT

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1992 IEEE INTERNATIONAL SYMP ON INTELLIGENT CONTROL

作者： RIMON, E BOYD, SP Robotics Laboratory Stanford University Department of Computer Science United States Information Systems Laboratory Stanford University Department of Electrical Engineering United States

ISBN: (纸本)0780305469

Knowledge of the distance between a robot and its surrounding environment is vital for any robotic system. The robot must obtain this information rapidly in order to plan and react in real-time. Our technique first surrounds the robot links and the obstacles by optimal ellipsoids, and then computes the clearance of the links from the obstacles with a generalized distance function. This approach offers an attractive alternative to the widely used technique of computing the distance via polyhedral representation of the robot and the obstacles. In particular, our approach offers a drastic reduction in the complexity of the data structures: each polyhedron, typically represented by a list of its features and their adjacency graph;is replaced by a minimum-volume ellipsoid represented by its center and a symmetric matrix whose dimension is either two or three (the workspace dimension). Moreover, while the computation time of the distance between polyhedra is often a function of their geometrical complexity, computation time in the ellipsoidal case is essentially constant;and becomes even more rapid when it is computed repeatedly along the robot's trajectory. Our method consists of the following two algorithms: The first computes the optimal ellipsoid surrounding a convex polyhedron. The second is an analytic formula for the free margin about one ellipsoid with respect to another, that is computed as a standard eigenvalue problem. An efficient incremental version of the latter algorithm is then proposed. This system has been implemented and preliminary simulation results are provided throughout the paper. © 1992 IEEE.

关键词： Geometry

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