ABSTRACT (FREE ACCESS LINK: http://authors.elsevier.com/a/1Q65W1HxM4UjNq) A method for the prepar... more ABSTRACT (FREE ACCESS LINK: http://authors.elsevier.com/a/1Q65W1HxM4UjNq) A method for the preparation of TiO2 thick films made of anatase nanocrystallites and featuring a mesoporous structure is described. Modification of a typical sol-gel synthesis that uses Titanium (IV) isopropoxide (TTIP) as precursor, through both the incorporation of a non-ionic surfactant (Tween 20) and the optimization of thermal treatments, allows to increase the thickness of each spin-coated layer, and to obtain by successive runs porous, transparent, homogeneous and crackless films with thickness up to 1.2 mm. The effect of the changing the Tween 20/TTIP ratio (R, ranging from 0.25 to 1.00) on the crystallographic, morphological and optical properties has been studied by X-ray Diffraction, N2 adsorption, UV-Visible Spectroscopy and Field Emission Scanning Electron Microscopy, in both powder and film form. The size of particles decreases slightly with increasing R, while the specific surface area increases somewhat. For all the R values, including R = 0, nanoparticles behave as direct semiconductors, in contrast with bulk anatase: changes in the band gap extent caused by the porous structure are negligible. Photo-electrochemical performance and carrier dynamics were studied using the films as anodes for the water photo-electrolysis reaction by means of Linear Sweep Voltammetry, Amperometry and Electrochemical Impedance Spectroscopy. Increasing R values improves the photocatalytic performance of the TiO2 films and leads to a comprehensive faster charge transfer at the oxide-solution interface, so that those with R = 1 offer highest performance, due to the combination of both higher thickness and improved quality of the material.
ABSTRACT Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, th... more ABSTRACT Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, thus easily up-scalable, anodic oxidation of a titanium foil followed by rapid thermal annealing. The structural/morphological characterization shows the formation of well defined one-dimensional nanotube carpets, while the X-ray diffraction analysis reveals the pure anatase crystalline structure of the thermal treated samples. The electrochemical response in laboratory-scale lithium cells is highly satisfying: at a very high discharge/charge rate of 12C, the NTs can perform with good stability and capacity retention after long-term cycling along with improved durability (>1100 cycles). High surface area, self-induced doping, short diffusion path and fast kinetics of the unidirectionally aligned TiO2 nanotube arrays are intriguing prospects which can be considered responsible for the noticeable electrochemical performance obtained in the absence of foreign ingredients such as binders and conductive agents, which would affect the overall energy density.
The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained... more The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained by laser powder bed fusion (LPBF) process. The potentiodynamic tests were carried out in solutions having different chloride contents. The results emphasize the role of chloride concentration on localized corrosion. The increase of concentration reduces pitting potential. In addition, the influence of the post-processing heat treatment temperature was recognized. Penetrating attacks occurred either on after low temperatures stress relieving or specimens without any treatment, promoted by selective dissolution of the α-Al phase stimulated by galvanic coupling with noble silicon precipitates at the border of the melt pool. Such penetrating morphology was not observed after heat treatments at high temperature.
The goal of the present work is to evaluate mechanical properties and to analyse the microstructu... more The goal of the present work is to evaluate mechanical properties and to analyse the microstructure of 316L stainless steel produced by Laser Powder Bed Fusion (L-PBF) follow by rolling with different thickness reduction under ambient and cryogenic conditions. The samples before rolling were heat treated. The static tensile test was realized at ambient and cryogenic (77K) conditions. The L-PBF powder metal production technology approved that is a key technology in the AM area, especially for metal powder materials. Mechanical properties tested at 298K and 77K shows that the application of various thermo-deformation rolling conditions increases of strength properties. Achieved mechanical properties are comparable to conventional bulk materials. The strength properties after the rolling under ambient and cryogenic conditions were significantly increased.
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA)
This paper discusses on the potential application of the selective laser melting technology to th... more This paper discusses on the potential application of the selective laser melting technology to the integration of microwave waveguide components in single monolithic parts. Three study cases working in Ku, K, or Ka bands are reported. For each study case, the correlation between the predicted and measured RF performance is significant. Benefits in terms of minimization of mass, envelope, interfaces and parts count are identified.
Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that allows the producti... more Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that allows the production of fully dense near net shape metal components using 3D CAD data as digital information. Despite the strong interest in this innovative technology, nowadays, only a few alloys can be processed by LPBF processes. There is therefore a strong interest in the development of new alloys especially designed for AM. In the present study the microstructure and the mechanical properties of three new aluminium alloys were investigated by means of laser single scan tracks experiments. In particular the new compositions were obtained by adding copper and silver to an AlSi10Mg powder and using a Al-Er pre-alloyed powder. The geometrical features and the microstructure of the scans were investigated and compared with the AlSi10Mg ones.
The Ti6Al4V alloy is the most used to fabricate hip prostheses. Additive Manufacturing technology... more The Ti6Al4V alloy is the most used to fabricate hip prostheses. Additive Manufacturing technology (AM) leads to obtain parts with geometry reproducing the anatomical shape of the patient through reverse engineering techniques. Moreover, it allows to obtain rough surfaces, which favor the osseointegration. On the other hand, the technology and the post-processing heat treatment modify the alloy microstructure and the passive film, with consequent alteration of the passivity current. The ions released into the human body can lead to allergic reactions, inflammation and chronic intoxication. For this reason, it is important to know the speed of dissolution of the alloy in passive conditions. The aim of this work is to determine the passivity current of the alloy in simulated body solution at 38 °C by means of short (60 hours) and long (2500 hours) potentiostatic tests, obtaining the passivity current in equilibrium conditions.
Abstract This paper presents a study of the microstructure evolution due to oxidation exposure of... more Abstract This paper presents a study of the microstructure evolution due to oxidation exposure of Inconel 625 (IN625) alloy produced by Laser Powder Bed Fusion (LPBF). IN625 is a nickel-based superalloy characterized by good mechanical properties, excellent oxidation, and corrosion resistance from cryogenic temperatures up to 980 °C, allowing its wide use in various harsh environments. In order to enable the application of LPBF IN625 components at high temperatures, the oxidation properties and microstructure of as-built and post-heat treated LPBF IN625 alloy must be carefully investigated. For this reason, an extensive characterization of the oxidation behavior of the alloy in the as-built condition and after solution treatment was performed. For both these conditions, the oxidation treatments were performed at 900 °C up to 96 h. The characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and scratch test analysis. The characteristics of the oxide layer and formed phases were investigated. The as-built IN625 state presented greater oxidation resistance compared to the solutionized IN625 one. The latter condition showed a defected oxide layer with the presence of Nb and Ni oxides inside the Cr oxide layer.
IEEE Antennas and Wireless Propagation Letters, 2018
In this letter, the design and the 3D printing of highperformance feed horns operating within Ku ... more In this letter, the design and the 3D printing of highperformance feed horns operating within Ku and V bands are presented. A smooth-wall architecture has been preferred in order to ease the manufacturing and to enhance the 3D printing quality. A suitable design procedure has been developed for the synthesis of dual-band smooth-wall feeds. Single-band and dualband all-metal prototypes have been manufactured through the selective laser melting technology. Remarkable agreement between the predicted and measured performances have been achieved also for the higher-frequency Q/V-band feed horn with measured return-loss higher than 33 dB, cross-polarization lower than-28 dB, and peak gain of 25dBi.
Inconel 625 (IN625) is a Ni superalloy ideal for the aeronautic and aerospace industries because ... more Inconel 625 (IN625) is a Ni superalloy ideal for the aeronautic and aerospace industries because of its superior mechanical and corrosion resistance properties. However, the production of components with complex geometries by traditional processes is very expensive, so additive manufacturing (AM) technologies can be applied to reduce the costs. In this work, IN625 alloy is processed by two different AM processes: selective laser melting (SLM) and laser metal deposition (LMD). First, the different powders are characterized, and then a parameter optimization is performed to obtain the highest possible density (over 99.8%) and hardness, showing very fine microstructures. The LMD process allows the highest build-up rate, but results in less dimensional accuracy and a lower hardness than the SLM process.
On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures ... more On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures by coupling the photo-reduction of metal precursors with 3D printing technology. The generated structures consist of metal nanoparticles embedded in a polymer matrix shaped into complex multilayered architectures. 3D conductive structures are fabricated with a digital light-processing printer incorporating silver salt into photocurable formulations.
Silver particles with spiky nanostructured morphologies have been obtained by two different wet-s... more Silver particles with spiky nanostructured morphologies have been obtained by two different wet-synthesis approaches. A detailed investigation was carried out into the synthesis parameters to tune the shape of the sample into desert-roseand succulent-like particles. The first synthetic route was based on the reduction of silver nitrate by iron sulfate in the presence of maleic acid as anisotropic agent, whereas in the second method ascorbic acid was used as the reducing agent and citric acid as the anisotropic agent. A nucleation model
Among carbon nanotubes (CNTs) based composites, aluminium/CNTs ones are rather promising for weig... more Among carbon nanotubes (CNTs) based composites, aluminium/CNTs ones are rather promising for weight sensitive applications, such as in aerospace field, thanks to the combination of the low weight and high stiffness and strength of the reinforcement. In this work, a self-assembled apparatus, named Pressure Assisted Fast Electric Sintering (PAFES), has been employed for the sintering of commercial micrometre size aluminium powders with multi-wall carbon nanotubes (MWCNTs). To do this effectively, much effort was devoted to the fundamental step of the CNTs dispersion and mixing in the Al powders by high energy milling.
2010 IEEE International Conference on Robotics and Biomimetics, 2010
In this paper we investigate the key factors associated with the realization of a hand exoskeleto... more In this paper we investigate the key factors associated with the realization of a hand exoskeleton that could be embedded in an astronaut glove for EVA (Extra Vehicular Activities). Such a project poses several and varied problems, mainly due to the complex structure of the human hand and to the extreme environment in which the glove operates. This work provides an overview of existing exoskeletons and their related technologies and lays the ground for the forthcoming prototype realization, by presenting a preliminary analysis of possible solutions in terms of mechanical structure, actuators and sensors.
41st International Conference on Environmental Systems, 2011
The total time of Extravehicular Activity (EVA) performed by astronauts has increased significant... more The total time of Extravehicular Activity (EVA) performed by astronauts has increased significantly during the past few years. On the other hand, the bulk and stiffness of the suit itself and in particular of the gloves generate some difficulties for the astronauts to perform their tasks in space. Therefore, it is necessary to improve the EVA glove technology for future needs. Since a lack of categorized information for those who want to improve EVA gloves is evident, in this work a survey on related literature has been carried out and fundamental data has been categorized. The paper starts with an overview on the historical and chronological progress of EVA suits and EVA gloves followed by a review of the previously demonstrated EVA gloves including American and Russian ones. The remaining part of the paper is dedicated to the characteristics of current EVA gloves and to present and future trends in research for further improvements.
41st International Conference on Environmental Systems, 2011
The human hand is a very particular limb: it has a wide range of degrees of freedom, permitting t... more The human hand is a very particular limb: it has a wide range of degrees of freedom, permitting to achieve a great variety of movements, and is also one of the most sensorized parts of the human body. These characteristics make it the most important tool for astronauts to perform extravehicular activity (EVA). However, mandatory EVA equipment strongly reduces hand performances, in particular as regards dexterity, tactile perception, mobility and fatigue. Several studies have been conducted to determine the influence of the EVA glove on manual capabilities, both in the past and more recently. This study presents experimental data regarding the performance decay which occurs in forces, fatigue and capability to execute tasks when wearing a non pressurized EVA glove, in comparison with bare-handed potential. Moreover, mechanical resistance of the glove has been measured and imposed pressure maps are presented. Results yield a deeper knowledge on how EVA gloves hinder human hand performance and how this is related to their stiffness. Nomenclature EVA = Extravehicular Activity EMU = Extravehicular Mobility Unit TMG = Thermal Micrometeoroid Garment EMG = Electromyography
41st International Conference on Environmental Systems, 2011
The human hand is an extremely complex system due to its large number of degrees of freedom (DoF)... more The human hand is an extremely complex system due to its large number of degrees of freedom (DoF) within a significantly reduced space. Moreover, it is required for most of the tasks performed by humans. That is why it is necessary to understand deeply all the characteristics of the human hand in order to develop devices interacting with it: to support it, to substitute injured parts, to help the recovery from injuries, or to enhance the performances while preserving its natural level of dexterity. The aim of this paper is to provide a complete and exhaustive summary of the kinematic, static and dynamic characteristics of the human hand as a preliminary step towards the development of hand devices such as prosthetic/robotic hands and exoskeletons. Both fields provide promising opportunities in research and space applications; the former through humanoid robotic helpers (e.g., Eurobot, Robonaut), the latter through the rising necessity to help the astronauts during Extravehicular Activity (EVA). In literature, several papers can be found analyzing kinematics, workspace, constraints and forces of the human hand 2,4. However this information is scattered among several papers, regarding in particular the exerted forces and the dependencies of joint forces and velocities from the angular values of the same joint or the adjacent one. Direct and inverse kinematics are presented for all the fingers and the data related to maximum forces, velocities, acceleration for each joint of each finger has been collected and is presented in this work.
Please note that technical editing may introduce minor changes to the text and/or graphics contai... more Please note that technical editing may introduce minor changes to the text and/or graphics contained in the manuscript submitted by the author(s) which may alter content, and that the standard Terms & Conditions and the ethical guidelines that apply to the journal are still applicable. In no event shall the RSC be held responsible for any errors or omissions in these Accepted Manuscript manuscripts or any consequences arising from the use of any information contained in them.
ABSTRACT (FREE ACCESS LINK: http://authors.elsevier.com/a/1Q65W1HxM4UjNq) A method for the prepar... more ABSTRACT (FREE ACCESS LINK: http://authors.elsevier.com/a/1Q65W1HxM4UjNq) A method for the preparation of TiO2 thick films made of anatase nanocrystallites and featuring a mesoporous structure is described. Modification of a typical sol-gel synthesis that uses Titanium (IV) isopropoxide (TTIP) as precursor, through both the incorporation of a non-ionic surfactant (Tween 20) and the optimization of thermal treatments, allows to increase the thickness of each spin-coated layer, and to obtain by successive runs porous, transparent, homogeneous and crackless films with thickness up to 1.2 mm. The effect of the changing the Tween 20/TTIP ratio (R, ranging from 0.25 to 1.00) on the crystallographic, morphological and optical properties has been studied by X-ray Diffraction, N2 adsorption, UV-Visible Spectroscopy and Field Emission Scanning Electron Microscopy, in both powder and film form. The size of particles decreases slightly with increasing R, while the specific surface area increases somewhat. For all the R values, including R = 0, nanoparticles behave as direct semiconductors, in contrast with bulk anatase: changes in the band gap extent caused by the porous structure are negligible. Photo-electrochemical performance and carrier dynamics were studied using the films as anodes for the water photo-electrolysis reaction by means of Linear Sweep Voltammetry, Amperometry and Electrochemical Impedance Spectroscopy. Increasing R values improves the photocatalytic performance of the TiO2 films and leads to a comprehensive faster charge transfer at the oxide-solution interface, so that those with R = 1 offer highest performance, due to the combination of both higher thickness and improved quality of the material.
ABSTRACT Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, th... more ABSTRACT Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, thus easily up-scalable, anodic oxidation of a titanium foil followed by rapid thermal annealing. The structural/morphological characterization shows the formation of well defined one-dimensional nanotube carpets, while the X-ray diffraction analysis reveals the pure anatase crystalline structure of the thermal treated samples. The electrochemical response in laboratory-scale lithium cells is highly satisfying: at a very high discharge/charge rate of 12C, the NTs can perform with good stability and capacity retention after long-term cycling along with improved durability (>1100 cycles). High surface area, self-induced doping, short diffusion path and fast kinetics of the unidirectionally aligned TiO2 nanotube arrays are intriguing prospects which can be considered responsible for the noticeable electrochemical performance obtained in the absence of foreign ingredients such as binders and conductive agents, which would affect the overall energy density.
The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained... more The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained by laser powder bed fusion (LPBF) process. The potentiodynamic tests were carried out in solutions having different chloride contents. The results emphasize the role of chloride concentration on localized corrosion. The increase of concentration reduces pitting potential. In addition, the influence of the post-processing heat treatment temperature was recognized. Penetrating attacks occurred either on after low temperatures stress relieving or specimens without any treatment, promoted by selective dissolution of the α-Al phase stimulated by galvanic coupling with noble silicon precipitates at the border of the melt pool. Such penetrating morphology was not observed after heat treatments at high temperature.
The goal of the present work is to evaluate mechanical properties and to analyse the microstructu... more The goal of the present work is to evaluate mechanical properties and to analyse the microstructure of 316L stainless steel produced by Laser Powder Bed Fusion (L-PBF) follow by rolling with different thickness reduction under ambient and cryogenic conditions. The samples before rolling were heat treated. The static tensile test was realized at ambient and cryogenic (77K) conditions. The L-PBF powder metal production technology approved that is a key technology in the AM area, especially for metal powder materials. Mechanical properties tested at 298K and 77K shows that the application of various thermo-deformation rolling conditions increases of strength properties. Achieved mechanical properties are comparable to conventional bulk materials. The strength properties after the rolling under ambient and cryogenic conditions were significantly increased.
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA)
This paper discusses on the potential application of the selective laser melting technology to th... more This paper discusses on the potential application of the selective laser melting technology to the integration of microwave waveguide components in single monolithic parts. Three study cases working in Ku, K, or Ka bands are reported. For each study case, the correlation between the predicted and measured RF performance is significant. Benefits in terms of minimization of mass, envelope, interfaces and parts count are identified.
Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that allows the producti... more Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that allows the production of fully dense near net shape metal components using 3D CAD data as digital information. Despite the strong interest in this innovative technology, nowadays, only a few alloys can be processed by LPBF processes. There is therefore a strong interest in the development of new alloys especially designed for AM. In the present study the microstructure and the mechanical properties of three new aluminium alloys were investigated by means of laser single scan tracks experiments. In particular the new compositions were obtained by adding copper and silver to an AlSi10Mg powder and using a Al-Er pre-alloyed powder. The geometrical features and the microstructure of the scans were investigated and compared with the AlSi10Mg ones.
The Ti6Al4V alloy is the most used to fabricate hip prostheses. Additive Manufacturing technology... more The Ti6Al4V alloy is the most used to fabricate hip prostheses. Additive Manufacturing technology (AM) leads to obtain parts with geometry reproducing the anatomical shape of the patient through reverse engineering techniques. Moreover, it allows to obtain rough surfaces, which favor the osseointegration. On the other hand, the technology and the post-processing heat treatment modify the alloy microstructure and the passive film, with consequent alteration of the passivity current. The ions released into the human body can lead to allergic reactions, inflammation and chronic intoxication. For this reason, it is important to know the speed of dissolution of the alloy in passive conditions. The aim of this work is to determine the passivity current of the alloy in simulated body solution at 38 °C by means of short (60 hours) and long (2500 hours) potentiostatic tests, obtaining the passivity current in equilibrium conditions.
Abstract This paper presents a study of the microstructure evolution due to oxidation exposure of... more Abstract This paper presents a study of the microstructure evolution due to oxidation exposure of Inconel 625 (IN625) alloy produced by Laser Powder Bed Fusion (LPBF). IN625 is a nickel-based superalloy characterized by good mechanical properties, excellent oxidation, and corrosion resistance from cryogenic temperatures up to 980 °C, allowing its wide use in various harsh environments. In order to enable the application of LPBF IN625 components at high temperatures, the oxidation properties and microstructure of as-built and post-heat treated LPBF IN625 alloy must be carefully investigated. For this reason, an extensive characterization of the oxidation behavior of the alloy in the as-built condition and after solution treatment was performed. For both these conditions, the oxidation treatments were performed at 900 °C up to 96 h. The characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and scratch test analysis. The characteristics of the oxide layer and formed phases were investigated. The as-built IN625 state presented greater oxidation resistance compared to the solutionized IN625 one. The latter condition showed a defected oxide layer with the presence of Nb and Ni oxides inside the Cr oxide layer.
IEEE Antennas and Wireless Propagation Letters, 2018
In this letter, the design and the 3D printing of highperformance feed horns operating within Ku ... more In this letter, the design and the 3D printing of highperformance feed horns operating within Ku and V bands are presented. A smooth-wall architecture has been preferred in order to ease the manufacturing and to enhance the 3D printing quality. A suitable design procedure has been developed for the synthesis of dual-band smooth-wall feeds. Single-band and dualband all-metal prototypes have been manufactured through the selective laser melting technology. Remarkable agreement between the predicted and measured performances have been achieved also for the higher-frequency Q/V-band feed horn with measured return-loss higher than 33 dB, cross-polarization lower than-28 dB, and peak gain of 25dBi.
Inconel 625 (IN625) is a Ni superalloy ideal for the aeronautic and aerospace industries because ... more Inconel 625 (IN625) is a Ni superalloy ideal for the aeronautic and aerospace industries because of its superior mechanical and corrosion resistance properties. However, the production of components with complex geometries by traditional processes is very expensive, so additive manufacturing (AM) technologies can be applied to reduce the costs. In this work, IN625 alloy is processed by two different AM processes: selective laser melting (SLM) and laser metal deposition (LMD). First, the different powders are characterized, and then a parameter optimization is performed to obtain the highest possible density (over 99.8%) and hardness, showing very fine microstructures. The LMD process allows the highest build-up rate, but results in less dimensional accuracy and a lower hardness than the SLM process.
On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures ... more On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures by coupling the photo-reduction of metal precursors with 3D printing technology. The generated structures consist of metal nanoparticles embedded in a polymer matrix shaped into complex multilayered architectures. 3D conductive structures are fabricated with a digital light-processing printer incorporating silver salt into photocurable formulations.
Silver particles with spiky nanostructured morphologies have been obtained by two different wet-s... more Silver particles with spiky nanostructured morphologies have been obtained by two different wet-synthesis approaches. A detailed investigation was carried out into the synthesis parameters to tune the shape of the sample into desert-roseand succulent-like particles. The first synthetic route was based on the reduction of silver nitrate by iron sulfate in the presence of maleic acid as anisotropic agent, whereas in the second method ascorbic acid was used as the reducing agent and citric acid as the anisotropic agent. A nucleation model
Among carbon nanotubes (CNTs) based composites, aluminium/CNTs ones are rather promising for weig... more Among carbon nanotubes (CNTs) based composites, aluminium/CNTs ones are rather promising for weight sensitive applications, such as in aerospace field, thanks to the combination of the low weight and high stiffness and strength of the reinforcement. In this work, a self-assembled apparatus, named Pressure Assisted Fast Electric Sintering (PAFES), has been employed for the sintering of commercial micrometre size aluminium powders with multi-wall carbon nanotubes (MWCNTs). To do this effectively, much effort was devoted to the fundamental step of the CNTs dispersion and mixing in the Al powders by high energy milling.
2010 IEEE International Conference on Robotics and Biomimetics, 2010
In this paper we investigate the key factors associated with the realization of a hand exoskeleto... more In this paper we investigate the key factors associated with the realization of a hand exoskeleton that could be embedded in an astronaut glove for EVA (Extra Vehicular Activities). Such a project poses several and varied problems, mainly due to the complex structure of the human hand and to the extreme environment in which the glove operates. This work provides an overview of existing exoskeletons and their related technologies and lays the ground for the forthcoming prototype realization, by presenting a preliminary analysis of possible solutions in terms of mechanical structure, actuators and sensors.
41st International Conference on Environmental Systems, 2011
The total time of Extravehicular Activity (EVA) performed by astronauts has increased significant... more The total time of Extravehicular Activity (EVA) performed by astronauts has increased significantly during the past few years. On the other hand, the bulk and stiffness of the suit itself and in particular of the gloves generate some difficulties for the astronauts to perform their tasks in space. Therefore, it is necessary to improve the EVA glove technology for future needs. Since a lack of categorized information for those who want to improve EVA gloves is evident, in this work a survey on related literature has been carried out and fundamental data has been categorized. The paper starts with an overview on the historical and chronological progress of EVA suits and EVA gloves followed by a review of the previously demonstrated EVA gloves including American and Russian ones. The remaining part of the paper is dedicated to the characteristics of current EVA gloves and to present and future trends in research for further improvements.
41st International Conference on Environmental Systems, 2011
The human hand is a very particular limb: it has a wide range of degrees of freedom, permitting t... more The human hand is a very particular limb: it has a wide range of degrees of freedom, permitting to achieve a great variety of movements, and is also one of the most sensorized parts of the human body. These characteristics make it the most important tool for astronauts to perform extravehicular activity (EVA). However, mandatory EVA equipment strongly reduces hand performances, in particular as regards dexterity, tactile perception, mobility and fatigue. Several studies have been conducted to determine the influence of the EVA glove on manual capabilities, both in the past and more recently. This study presents experimental data regarding the performance decay which occurs in forces, fatigue and capability to execute tasks when wearing a non pressurized EVA glove, in comparison with bare-handed potential. Moreover, mechanical resistance of the glove has been measured and imposed pressure maps are presented. Results yield a deeper knowledge on how EVA gloves hinder human hand performance and how this is related to their stiffness. Nomenclature EVA = Extravehicular Activity EMU = Extravehicular Mobility Unit TMG = Thermal Micrometeoroid Garment EMG = Electromyography
41st International Conference on Environmental Systems, 2011
The human hand is an extremely complex system due to its large number of degrees of freedom (DoF)... more The human hand is an extremely complex system due to its large number of degrees of freedom (DoF) within a significantly reduced space. Moreover, it is required for most of the tasks performed by humans. That is why it is necessary to understand deeply all the characteristics of the human hand in order to develop devices interacting with it: to support it, to substitute injured parts, to help the recovery from injuries, or to enhance the performances while preserving its natural level of dexterity. The aim of this paper is to provide a complete and exhaustive summary of the kinematic, static and dynamic characteristics of the human hand as a preliminary step towards the development of hand devices such as prosthetic/robotic hands and exoskeletons. Both fields provide promising opportunities in research and space applications; the former through humanoid robotic helpers (e.g., Eurobot, Robonaut), the latter through the rising necessity to help the astronauts during Extravehicular Activity (EVA). In literature, several papers can be found analyzing kinematics, workspace, constraints and forces of the human hand 2,4. However this information is scattered among several papers, regarding in particular the exerted forces and the dependencies of joint forces and velocities from the angular values of the same joint or the adjacent one. Direct and inverse kinematics are presented for all the fingers and the data related to maximum forces, velocities, acceleration for each joint of each finger has been collected and is presented in this work.
Please note that technical editing may introduce minor changes to the text and/or graphics contai... more Please note that technical editing may introduce minor changes to the text and/or graphics contained in the manuscript submitted by the author(s) which may alter content, and that the standard Terms & Conditions and the ethical guidelines that apply to the journal are still applicable. In no event shall the RSC be held responsible for any errors or omissions in these Accepted Manuscript manuscripts or any consequences arising from the use of any information contained in them.
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Papers by Diego Manfredi