A Lightweight Robotic Device Based on a Micro-Macro Actuation Concept for the Inspection of Railway Pantograph

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Giancarlo Santamato ◽  
Domenico Chiaradia ◽  
Massimiliano Solazzi ◽  
Antonio Frisoli
Keyword(s):  
High Frequency ◽  
Structural Integrity ◽  
Passive Movement ◽  
Functional Verification ◽  
Robotic Device ◽  
Structural Dynamic ◽  
Actuation System ◽  
Periodic Maintenance ◽  
Lightweight Structure ◽  
Robotic Devices

Abstract Functional verification of railway pantographs is performed within periodic maintenance programs by means of specifically designed automation and robotic devices that can check their structural integrity and correct functionality. In this paper, we present the design and validation of a new portable inspection robotic device that through structural dynamic excitation and passive movement can assess the health status of railway pantographs. The device is endowed with a new actuation system that combines the large range of force attained through a macro-actuator with the high-frequency capabilities of a micro-actuator while preserving lightweight structure. The reported design and experiments confirm that excitation transmission by accurate force control can be achieved in the entire frequency range, despite the interaction between actuator and structure, and that simulated defects can be revealed by low and high-frequency alterations.

scholarly journals A Wearable Robotic Device Based on Twisted String Actuation for Rehabilitation and Assistive Applications

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Mohssen Hosseini ◽  
Roberto Meattini ◽  
Gianluca Palli ◽  
Claudio Melchiorri
Keyword(s):  
Force Sensor ◽  
Robotic Device ◽  
Actuation System ◽  
Arm Rehabilitation ◽  
Basic Force ◽  
Twisted String ◽  
Working Principle ◽  
Robotic Devices ◽  
Robotic Applications ◽  
Electromyography Signals

The preliminary experimental study toward the implementation of an arm rehabilitation device based on a twisted string actuation module is presented. The actuation module is characterized by an integrated force sensor based on optoelectronic components. The adopted actuation system can be used for a wide set of robotic applications and is particularly suited for very compact, light-weight, and wearable robotic devices, such as wearable rehabilitation systems and exoskeletons. Thorough presentation and description of the proposed actuation module as well as the basic force sensor working principle are illustrated and discussed. A conceptual design of a wearable arm assistive system based on the proposed actuation module is presented. Moreover, the actuation module has been used in a simple assistive application, in which surface-electromyography signals are used to detect muscle activity of the user wearing the system and to regulate the support action provided to the user to reduce his effort, showing in this way the effectiveness of the approach.

scholarly journals The Actuation System of the Ankle Exoskeleton T-FLEX: First Use Experimental Validation in People with Stroke

2021 ◽  
Vol 11 (4) ◽  
pp. 412
Author(s):  
Daniel Gomez-Vargas ◽  
Felipe Ballen-Moreno ◽  
Patricio Barria ◽  
Rolando Aguilar ◽  
José M. Azorín ◽  
...  
Keyword(s):  
Inertial Sensor ◽  
Movement Analysis ◽  
Biomechanical Analysis ◽  
Gait Patterns ◽  
Positive Effects ◽  
General Terms ◽  
Actuation System ◽  
Abnormal Gait ◽  
Ankle Kinematics ◽  
Robotic Devices

Robotic devices can provide physical assistance to people who have suffered neurological impairments such as stroke. Neurological disorders related to this condition induce abnormal gait patterns, which impede the independence to execute different Activities of Daily Living (ADLs). From the fundamental role of the ankle in walking, Powered Ankle-Foot Orthoses (PAFOs) have been developed to enhance the users’ gait patterns, and hence their quality of life. Ten patients who suffered a stroke used the actuation system of the T-FLEX exoskeleton triggered by an inertial sensor on the foot tip. The VICONmotion capture system recorded the users’ kinematics for unassisted and assisted gait modalities. Biomechanical analysis and usability assessment measured the performance of the system actuation for the participants in overground walking. The biomechanical assessment exhibited changes in the lower joints’ range of motion for 70% of the subjects. Moreover, the ankle kinematics showed a correlation with the variation of other movements analyzed. This variation had positive effects on 70% of the participants in at least one joint. The Gait Deviation Index (GDI) presented significant changes for 30% of the paretic limbs and 40% of the non-paretic, where the tendency was to decrease. The spatiotemporal parameters did not show significant variations between modalities, although users’ cadence had a decrease of 70% of the volunteers. Lastly, the satisfaction with the device was positive, the comfort being the most user-selected aspect. This article presents the assessment of the T-FLEX actuation system in people who suffered a stroke. Biomechanical results show improvement in the ankle kinematics and variations in the other joints. In general terms, GDI does not exhibit significant increases, and the Movement Analysis Profile (MAP) registers alterations for the assisted gait with the device. Future works should focus on assessing the full T-FLEX orthosis in a larger sample of patients, including a stage of training.

Finite Element Dynamic Analysis of a Railway Seat Under Longitudinal Impact Condition

2011 ◽  
Author(s):  
Francesco Caputo ◽  
Giuseppe Lamanna ◽  
Alessandro Soprano
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Seat Belt ◽  
Element Model ◽  
Railway Vehicle ◽  
Longitudinal Impact ◽  
Structural Behaviour ◽  
Structural Dynamic ◽  
Sled Test ◽  
Seat Frame

For a railway vehicle, the structural integrity of the seat frame and of its connection to that of the coach is a very important aspect of the design phase addressed to the improvement of the passive safety performances, at most because the analysis of the accidents occurred in recent years shows that secondary impacts against vehicle interiors remain one of the main causes of injury. All regulations which apply to this task start from the assumption that whatever happens to the vehicle the seat must remain connected to the vehicle frame, as well as the different parts to each other. Numerical evaluations are obviously necessary to match with this design requirement; it would be desirable to apply multi-body (MB) codes to this task, as they are really fast, but unfortunately they can’t provide detailed results for what concerns the structural behaviour of the involved seat and vehicle components. For this reason, in the present work a full finite element model of a sled-test, including a FE dummy, has been developed, analysed and validated by comparison with the available experimental results; it has been also showed how this kind of numerical simulation is suited and necessary to evaluate the structural behaviour of the structural components of the seat frame. In the context of the presented study the MADYMO® code has been adopted to perform the preliminary MB analyses necessary to calibrate and evaluate the relevant parameters of dummy-seat contact surfaces and of seat-belt stiffness, while LS DYNA® code has been used for the structural dynamic FE analyses.

scholarly journals Structural Low-Level Dynamic Response Analysis Using Deviations of Idealized Edge Profiles and Video Acceleration Magnification

2019 ◽  
Vol 9 (4) ◽  
pp. 712
Author(s):  
Dashan Zhang ◽  
Liangfei Fang ◽  
Ye Wei ◽  
Jie Guo ◽  
Bo Tian
Keyword(s):  
High Frequency ◽  
Vibration Characteristics ◽  
Response Analysis ◽  
Test Beam ◽  
Structural Dynamic ◽  
Vibration Signals ◽  
High Frequency Vibration ◽  
Low Level ◽  
Beam Experiment ◽  
Noise Barrier

The development of high-speed camera systems and image processing techniques has promoted the use of vision-based methods as a practical alternative for the analysis of non-contact structural dynamic responses. In this study, a deviation extraction method is introduced to obtain deviation signals from structural idealized edge profiles. Given that the deviation temporal variations can reflect the structural vibration characteristics, a method based on singular-value decomposition (SVD) is proposed to extract valuable vibration signals from the matrix composed of deviations from all video frames. However, this method exhibits limitations when handling low-level motions that reflect high-frequency vibration components. Hence, a video acceleration magnification algorithm is employed to enhance low-level deviation variations before the extraction. The enhancement of low-level deviation variations is validated by a light-weight cantilever beam experiment and a noise barrier field test. From the extracted waveforms and their spectrums from the original and magnified videos, subtle deviations of the selected straight-line edge profiles are magnified in the reconstructed videos, and low-level high-frequency vibration signals are successfully enhanced in the final extraction results. Vibration characteristics of the test beam and the noise barrier are then analyzed using signals obtained by the proposed method.

Amino Acid and Secondary Structure Integrity of Sonicated Milk Proteins

2020 ◽  
Vol 73 (3) ◽  
pp. 170 ◽  
Author(s):  
Rachana Pathak ◽  
Thomas S. H. Leong ◽  
Gregory J. O. Martin ◽  
Muthupandian Ashokkumar
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Acid Content ◽  
High Frequency ◽  
Structural Integrity ◽  
Skim Milk ◽  
Low Frequency ◽  
Amino Acid Content ◽  
Milk Proteins ◽  
Dairy Proteins

This study investigated the effect of low-frequency (20kHz) and high-frequency (414kHz) ultrasound treatment on the amino acid and secondary structural integrity of dairy proteins. Sonicated skim milk proteins were hydrolysed and analysed with reverse-phase high-performance liquid chromatography to investigate the amino acid content of the processed samples. It was successfully demonstrated that both low-frequency and high-frequency ultrasound did not adversely affect the amino acid content, even after prolonged extreme processing conditions (6h, 355kHz). This finding was supplemented with protein secondary structure data (Fourier-transform (FT)-IR secondary derivatives of the amide I band, 1700–1600cm−1) that showed that ultrasound was capable of causing structural modifications to the dairy proteins. This study shows that ultrasound can be used to influence protein–protein interactions in skim milk via alterations to the secondary structure without degrading the amino acids in the proteins.

Effects of High Frequency Hydrodynamic Loads on Structural Integrity and Mechanical Operability of Valves

2015 ◽  
Author(s):  
Yigit Isbiliroglu ◽  
Cagri Ozgur ◽  
Evren Ulku ◽  
Nish Vaidya ◽  
Kristofor Paserba
Keyword(s):  
High Frequency ◽  
Structural Integrity ◽  
Energy Content ◽  
Hybrid Approach ◽  
Piping System ◽  
Seismic Loads ◽  
Damage Potential ◽  
Element Analysis ◽  
Piping Systems ◽  
Number Of Cycles

In-line valves are qualified for static as well as dynamic loads from seismic and hydrodynamic (HD) events. Seismic loads are generally characterized by frequency content less than about 33 Hz whereas HD loads may exhibit a broad range of frequencies greater than 33 Hz. HD loads may also result in spectral accelerations significantly in excess of those due to the design basis seismic events. Current regulatory guidelines do not specifically address the evaluation of equipment response to high frequency loading. This paper investigates the response of skid and line mounted valves of piping systems under HD loads by using several independent rigorous finite element analysis solutions for various piping system segments. It presents a hybrid approach for the evaluation of the response of valves to HD and seismic loads. The proposed approach significantly reduces the amount of individual analysis and testing needed to qualify the valves. First, valve responses are evaluated on the basis of displacements since HD loads are generally characterized by high frequencies and small durations. Second, the damage potential of the loads on the valve actuators is represented by the energy imparted to the actuator quantified in terms of Arias intensity. The rationale for using the energy content is based on the fact that damage due to dynamic loading is related not only to the amplitude of the acceleration response but also to the duration and the number of cycles over which this acceleration is imposed.

scholarly journals Modal testing for model validation of structures with discrete nonlinearities

2015 ◽  
Vol 373 (2051) ◽  
pp. 20140410 ◽  
Author(s):  
D. J. Ewins ◽  
B. Weekes ◽  
A. delli Carri
Keyword(s):  
Model Validation ◽  
Nonlinear Response ◽  
Structural Integrity ◽  
Linear Models ◽  
Recent Literature ◽  
Modal Testing ◽  
Structural Dynamic ◽  
Nonlinear Features ◽  
Using Data ◽  
Further Development

Model validation using data from modal tests is now widely practiced in many industries for advanced structural dynamic design analysis, especially where structural integrity is a primary requirement. These industries tend to demand highly efficient designs for their critical structures which, as a result, are increasingly operating in regimes where traditional linearity assumptions are no longer adequate. In particular, many modern structures are found to contain localized areas, often around joints or boundaries, where the actual mechanical behaviour is far from linear. Such structures need to have appropriate representation of these nonlinear features incorporated into the otherwise largely linear models that are used for design and operation. This paper proposes an approach to this task which is an extension of existing linear techniques, especially in the testing phase, involving only just as much nonlinear analysis as is necessary to construct a model which is good enough, or ‘valid’: i.e. capable of predicting the nonlinear response behaviour of the structure under all in-service operating and test conditions with a prescribed accuracy. A short-list of methods described in the recent literature categorized using our framework is given, which identifies those areas in which further development is most urgently required.

scholarly journals Prepositional units, formed on the basis of prepositional-noun forms (based on the material of modern Russian media)

2020 ◽  
Vol 7 (4) ◽  
pp. 418-427
Author(s):  
Haiyan Zhou ◽  
Keyword(s):  
High Frequency ◽  
Structural Integrity ◽  
Point Of View ◽  
Lexical Unit ◽  
The Third ◽  
Frequency Of Use ◽  
Close Relationship ◽  
Russian Media ◽  
Similarities And Differences ◽  
Modern Russian

The article deals with prepositional units formed on the basis of prepositional-noun and widely used in modern Russian media. These units were studied in different aspects and were referred to by different terms. We, following M. V. Vsevolodova, use the broader term “prepositional units” and divide prepositional units into three groups. The first group includes prepositional units of the type ввиду (чего-н.), вместо (кого-чего-н.), вроде (кого-чего-н.), which have a structural integrity. The second group includes such as в силу (чего-н.), в честь (кого-чего-н.), в течение (чего-н.), which differ separately. The third group is prepositional units of the type в рамках (чего-н.), в области (чего-н.), на фоне (чего-н.), etc., which were characterized by the possible insertion of consistent adjectives or pronouns. In the article, using the transitivity scale of V. V. Babaytseva, the similarities and differences of prepositional units are revealed, and the stages they occupy on the path of identification depending on the specifi use are revealed. From the point of view of the diachronic transition of language phenomena, these prepositional units reflect the process of their lexicalization, that is, it is clear that they have turned from separate syntactic units into a single lexical unit. On the other hand, there is also a grammaticalization process, that is, there is a desemanization and decategorization of each element within the unit. It indicates a close relationship between lexicalization and grammaticalization. The functional similarity of the prepositional forms of the noun and the preposition, a high frequency of use «предлог+падежная форма существительного» facilitate the transition into the prepositional units.

scholarly journals Transient high-frequency elasto-acoustic response of a vehicular drivetrain to sudden throttle demand

2001 ◽  
Vol 215 (1) ◽  
pp. 35-52 ◽  
Author(s):  
S Vafaei ◽  
M Menday ◽  
H Rahnejat
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Structural Response ◽  
Frequency Noise ◽  
Structural Dynamic ◽  
Shell Elements ◽  
Root Cause ◽  
Road Users ◽  
Drive Condition ◽  
Processing Techniques

This paper presents an experimental investigation of the high-frequency structural response of vehicular powertrain systems when subjected to sudden surge in output torque demand as in throttle tip-in from coast to drive condition. The lightly damped drivetrain system has many lash zones represented by low stiffness components and thin shell elements with large modal densities. The high-frequency noise and structural dynamic modes excited under impact conditions through low lash rate zones are of short transitory nature but a major concern to vehicle drivers and other road users alike. An investigation of the root cause of these transitory events requires state-of-the art signal processing techniques at reasonably high sampling rates. This paper presents the results of an investigation into the driveline clonk problem and establishes the relationship between this phenomenon and the low-frequency shuffle of the vehicle.

31. Low- and high-frequency subcortical SEP amplitude reduction during pure passive movement

2013 ◽  
Vol 124 (11) ◽  
pp. e196
Author(s):  
A. Insola ◽  
P. Mazzone ◽  
M. Valeriani
Keyword(s):  
High Frequency ◽  
Passive Movement
Sign in / Sign up

Export Citation Format

Share Document