FLEGX: A Jumping Flexible Robotic Leg

2017 ◽  
Author(s):  
Daniele Ludovico ◽  
Mariapaola D’Imperio ◽  
Ferdinando Cannella
Keyword(s):  
Energy Efficient ◽  
Humanoid Robot ◽  
Numerical Models ◽  
Experimental Tests ◽  
Efficient Solutions ◽  
Flexible Link ◽  
Dynamic Features ◽  
Integrated Environment ◽  
Physical Prototype ◽  
Robotic Leg

Nowadays the robotic challenges are various and many of these are oriented towards bioinspired, safe and energy efficient solutions. Considering these needs, the authors propose the development of a flexible robotic leg as a first step in the design of a jumping humanoid robot. The virtual prototyping techniques played a key role in the identification of the optimal geometric and dynamic features of the leg, such as the length and thickness of the flexible link or the inertial properties of the whole system, and in the choice of the most suitable mechanical and electromechanical components. Several simulations were performed using the software MSC.Nastran® and MSC.Adams® - Matlab/Simulink® integrated environment and their results will be presented. Future works concern the assembly of a physical prototype and an extended campaign of experimental tests to collect data useful for validate the numerical models.

Towards Multi-Body Analyses for Advanced Flexible Robotic Systems

2017 ◽  
Author(s):  
Mariapaola D’Imperio ◽  
Carlo Canali ◽  
Darwin Caldwell ◽  
Ferdinando Cannella ◽  
Cristiano Pizzamiglio ◽  
...  
Keyword(s):  
Design Process ◽  
Development Process ◽  
Virtual Prototyping ◽  
Experimental Tests ◽  
Research Field ◽  
Robotic Systems ◽  
Global Competition ◽  
Physical Prototype ◽  
Multi Body ◽  
Robotic Leg

Manufacturers answered to the global competition rise by increasing the efficiency of their development process by substituing the hardware tests with their virtual counterpart. Following the same idea, in this paper, the introduction of the virtual prototyping technique in the design of a complex robotic leg is proposed. The novelty of this work is double: the first motivation lies on the characteristic of the mechanism, since it is a FLEXible jumping LEG; the second one, instead, regards to the introduction of methods well known in other research field but rarely used in robotics. This paper describes the whole design process, while the assembly of the physical prototype, the control development and the experimental tests will be matters of future works.

scholarly journals Additively Manufactured Parts Made of a Polymer Material Used for the Experimental Verification of a Component of a High-Speed Machine with an Optimised Geometry—Preliminary Research

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 137
Author(s):  
Artur Andrearczyk ◽  
Bartlomiej Konieczny ◽  
Jerzy Sokołowski
Keyword(s):  
Polymer Material ◽  
High Speed ◽  
Numerical Models ◽  
Flow Analysis ◽  
Experimental Tests ◽  
Strength Analysis ◽  
Compressor Wheel ◽  
Operational Characteristics ◽  
3D Printed ◽  
Novel Method

This paper describes a novel method for the experimental validation of numerically optimised turbomachinery components. In the field of additive manufacturing, numerical models still need to be improved, especially with the experimental data. The paper presents the operational characteristics of a compressor wheel, measured during experimental research. The validation process included conducting a computational flow analysis and experimental tests of two compressor wheels: The aluminium wheel and the 3D printed wheel (made of a polymer material). The chosen manufacturing technology and the results obtained made it possible to determine the speed range in which the operation of the tested machine is stable. In addition, dynamic destructive tests were performed on the polymer disc and their results were compared with the results of the strength analysis. The tests were carried out at high rotational speeds (up to 120,000 rpm). The results of the research described above have proven the utility of this technology in the research and development of high-speed turbomachines operating at speeds up to 90,000 rpm. The research results obtained show that the technology used is suitable for multi-variant optimization of the tested machine part. This work has also contributed to the further development of numerical models.

scholarly journals Numerical and experimental evaluation of masonry prisms by finite element method

2017 ◽  
Vol 10 (2) ◽  
pp. 477-508 ◽  
Author(s):  
C. F.R. SANTOS ◽  
R. C. S. S. ALVARENGA ◽  
J. C. L. RIBEIRO ◽  
L. O CASTRO ◽  
R. M. SILVA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
High Strength Concrete ◽  
Numerical Models ◽  
High Strength ◽  
Experimental Tests ◽  
Experimental Results ◽  
Concrete Blocks ◽  
Micro Modeling ◽  
Modeling Strategy

Abstract This work developed experimental tests and numerical models able to represent the mechanical behavior of prisms made of ordinary and high strength concrete blocks. Experimental tests of prisms were performed and a detailed micro-modeling strategy was adopted for numerical analysis. In this modeling technique, each material (block and mortar) was represented by its own mechanical properties. The validation of numerical models was based on experimental results. It was found that the obtained numerical values of compressive strength and modulus of elasticity differ by 5% from the experimentally observed values. Moreover, mechanisms responsible for the rupture of the prisms were evaluated and compared to the behaviors observed in the tests and those described in the literature. Through experimental results it is possible to conclude that the numerical models have been able to represent both the mechanical properties and the mechanisms responsible for failure.

Super-long span bridge aerodynamics: on-going results of the TG3.1 benchmark test – Step 1.2

2019 ◽  
Author(s):  
Giorgio Diana ◽  
Stoyan Stoyanoff ◽  
Andrew Allsop ◽  
Luca Amerio ◽  
Tommaso Argentini ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Tests ◽  
Numerical Comparison ◽  
Aeroelastic Stability ◽  
Turbulent Wind ◽  
Long Span Bridges ◽  
Buffeting Response ◽  
Long Span ◽  
Long Span Bridge ◽  
Sectional Model

<p>This paper is part of a series of publications aimed at the divulgation of the results of the 3-step benchmark proposed by the IABSE Task Group 3.1 to define reference results for the validation of the software that simulate the aeroelastic stability and the response to the turbulent wind of super-long span bridges. Step 1 is a numerical comparison of different numerical models both a sectional model (Step 1.1) and a full bridge (Step 1.2) are studied. Step 2 will be the comparison of predicted results and experimental tests in wind tunnel. Step 3 will be a comparison against full scale measurements.</p><p>The results of Step 1.1 related to the response of a sectional model were presented to the last IABSE Symposium in Nantes 2018. In this paper, the results of Step 1.2 related to the response long-span full bridge are presented in this paper both in terms of aeroelastic stability and buffeting response, comparing the results coming from several TG members.</p>

scholarly journals NUMERICAL ANALYSIS OF CORRUGATED STEEL PLATE BRIDGE WITH REINFORCED CONCRETE RELIEVING SLAB

2015 ◽  
Vol 22 (5) ◽  
pp. 585-596 ◽  
Author(s):  
Damian BEBEN ◽  
Adam STRYCZEK
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Steel Plate ◽  
Numerical Models ◽  
Experimental Tests ◽  
Bridge Engineering ◽  
Steel Plates ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Rc Slab

The paper presents a numerical analysis of corrugated steel plate (CSP) bridge with reinforced concrete (RC) relieving slab under static loads. Calculations were made based on the finite element method using Abaqus software. Two computation models were used; in the first one, RC slab was used, and the other was without it. The effect of RC slab to deformations of CSP shell was determined. Comparing the computational results from two numerical models, it can be concluded that when the relieving slab is applied, substantial reductions in displacements, stresses, bending mo­ments and axial thrusts are achieved. Relative reductions of displacements were in the range of 53–66%, and stresses of 73–82%. Maximum displacements and bending moments were obtained at the shell crown, and maximum stresses and axial thrusts at the quarter points. The calculation results were also compared to the values from experimental tests. The course of computed displacements and stresses is similar to those obtained from experimental tests, although the absolute values were generally higher than the measured ones. Results of numerical analyses can be useful for bridge engineering, with particular regard to bridges and culverts made from corrugated steel plates for the range of necessity of using additional relieving elements.

Regenerative effects in the Sit-to-Stand and Stand-to-Sit movement

Robotica ◽  
2014 ◽  
Vol 33 (1) ◽  
pp. 107-126 ◽  
Author(s):  
Ronnie Joseph Wong ◽  
James Andrew Smith
Keyword(s):  
Energy Efficient ◽  
Humanoid Robot ◽  
Humanoid Robots ◽  
Gear Ratio ◽  
Scale Model ◽  
Hip Joints ◽  
Regenerative Effect ◽  
Sit To Stand ◽  
A Value ◽  
Nimh Battery

SUMMARYWhile Sit-to-Stand and Stand-to-Sit are routine activities and are crucial pre-requisites to walking and running their underlying dynamics are poorly understood. Furthermore, the potential for using these movements to regenerate energy in energy-sensitive devices such as orthoses, prostheses and humanoid robots has never been examined. Insights in this domain can lead to more energy-efficient prosthesis, orthosis and humanoid robot designs.OBJECTIVES: The objectives are two-fold: first, to determine how much energy can be regenerated during standard movements related to transitions between sitting and standing on a scale humanoid model and second, to determine if the chosen actuator could produce better results if the gear ratio were modified. This manuscript's main contribution to the literature is by showing which joint provides the most regenerative effect during transitions between sitting and standing.MODEL DESIGN AND IMPLEMENTATION: Joint trajectories from existing biomechanics trials of sitting and standing transitions were fed into a 1/10 scale model of a humanoid robot. The robot model, developed in MapleSim, is comprised of standard and off-the-shelf subcomponents, including amplifier, NiMH battery and Robotis Dynamixel RX-28 actuators.RESULTS: Using the RX-28 actuator, the ankle, knee and hip joints all show a degree of regenerative effects, the hip demonstrates the most dramatic levels during the transition from standing to sitting. This contrasts with recent publications which show that the knee has the most important regenerative effects during walking and running. It is also found that for under 3 degree trajectory error the regenerative effect is best for all joints when the gear ratio is increased from the RX-28's 193:1 value to a value of approximately 760:1 for the ankle, 630:1 for the knee and 600:1 for the hip.CONCLUSIONS: During transitions between sitting and standing the greatest potential for regeneration occurs in the hips. Therefore, systems designed to implement regenerative effects between sitting and standing need to include subsystems at the hip for maximum regenerative effects.

scholarly journals Feedforward Tactical Optimization for Energy-Efficient Operation of Freight Trains: The Swiss Case

2018 ◽  
Vol 2672 (10) ◽  
pp. 278-288 ◽  
Author(s):  
Valerio De Martinis ◽  
Ambra Toletti ◽  
Francesco Corman ◽  
Ulrich A. Weidmann ◽  
Andrew Nash
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Real Data ◽  
Efficient Solutions ◽  
Future Market ◽  
Speed Profile ◽  
Efficient Operation ◽  
The North ◽  
Simulation Based ◽  
Profile Optimization

The optimization of rail operation for improving energy efficiency plays an important role for the current and future market of rail freight services and helps rail compete with other transport modes. This paper presents a feedforward simulation-based model that performs speed profile optimization together with minor rescheduling actions. The model’s purpose is to provide railway operators and infrastructure managers with energy-efficient solutions that are tailored especially for freight trains. This work starts from the assumption that freight train characteristics are completely defined only a few hours before actual departure; therefore, small specific feedforward adjustments that do not affect the surrounding operation can still be considered. The model was tested in a numerical example. The example clearly shows how the optimized solutions can be evaluated with reference to energy saved and robustness within the rail traffic. The evaluation is based on real data from the North–South corridor crossing Switzerland from Germany to Italy.

scholarly journals Knee-stretched walking with toe-off and heel-strike for a position-controlled humanoid robot based on model predictive control

2021 ◽  
Vol 18 (4) ◽  
pp. 172988142110362
Author(s):  
Zelin Huang ◽  
Zhangguo Yu ◽  
Xuechao Chen ◽  
Qingqing Li ◽  
Libo Meng ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Energy Efficient ◽  
Humanoid Robot ◽  
Center Of Mass ◽  
Heel Strike ◽  
Gait Generation ◽  
Double Support ◽  
Transition Moments ◽  
Efficient Gait

Knee-stretched walking is considered to be a human-like and energy-efficient gait. The strategy of extending legs to obtain vertical center of mass trajectory is commonly used to avoid the problem of singularities in knee-stretched gait generation. However, knee-stretched gait generation utilizing this strategy with toe-off and heel-strike has kinematics conflicts at transition moments between single support and double support phases. In this article, a knee-stretched walking generation with toe-off and heel-strike for the position-controlled humanoid robot has been proposed. The position constraints of center of mass have been considered in the gait generation to avoid the kinematics conflicts based on model predictive control. The method has been verified in simulation and validated in experiment.

A Probabilistic Approach for the Assessment of LOC Events in Steel Storage Tanks Under Seismic Loading

2018 ◽  
Author(s):  
Fabrizio Paolacci ◽  
Daniele Corritore ◽  
Antonio C. Caputo ◽  
Oreste S. Bursi ◽  
Bledar Kalemi
Keyword(s):  
Numerical Models ◽  
Simple Procedure ◽  
Probabilistic Approach ◽  
Seismic Loading ◽  
Experimental Tests ◽  
Seismic Intensity ◽  
Storage Tanks ◽  
Industrial Plants ◽  
Damage States ◽  
Relationship Of

The damage states in a storage tank subjected to seismic loading can induce loss of containment (LOC) with possible consequences (fire, explosion, etc..) both for the surrounding units and people. This aspect is particularly crucial for the Quantitative Risk Analysis (QRA) of industrial plants subjected to earthquakes. Classical QRA methodologies are based on standard LOC conditions whose frequency of occurrence is mainly related to technological accident rather than natural events and are thus useless. Therefore, it is evident the necessity of establishing new procedures for the evaluation of the frequencies of occurrence of LOC events in storage tanks when subjected to an earthquake. Consequently, in this work a simple procedure founded on a probabilistic linear regression-based model is proposed, which uses simplified numerical models typically adopted for the seismic response of above ground storage tanks. Based on a set of predetermined LOC events (e.g. damage in the pipes, damage in the nozzles, etc..), whose probabilistic relationship with the local response (stress level, etc..) derives from experimental tests, the probabilistic relationship of selected response parameters with the seismic intensity measure (IM) is established. As result, for each LOC event, the cloud analysis method is used to derive the related fragility curve.

scholarly journals Sandwich Panels with Polymeric Foam Cores Exposed to Blast Loading: An Experimental and Numerical Investigation

2020 ◽  
Vol 10 (24) ◽  
pp. 9061
Author(s):  
Kristoffer Aune Brekken ◽  
Aase Reyes ◽  
Torodd Berstad ◽  
Magnus Langseth ◽  
Tore Børvik
Keyword(s):  
Shock Tube ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Experimental Tests ◽  
Quantitative Agreement ◽  
Low Velocity Impact ◽  
Blast Load ◽  
Low Velocity ◽  
Skin Deformation

Sandwich panels have proven to be excellent energy absorbents. Such panels may be used as a protective structure in, for example, façades subjected to explosions. In this study, the dynamic response of sandwich structures subjected to blast loading has been investigated both experimentally and numerically, utilizing a shock tube facility. Sandwich panels made of aluminium skins and a core of extruded polystyrene (XPS) with different densities were subjected to various blast load intensities. Low-velocity impact tests on XPS samples were also conducted for validation and calibration of a viscoplastic extension of the Deshpande-Fleck crushable foam model. The experimental results revealed a significant increase in blast load mitigation for sandwich panels compared to skins without a foam core, and that the back-skin deformation and the core compression correlated with the foam density. Numerical models of the shock tube tests were created using LS-DYNA, incorporating the new viscoplastic formulation of the foam material. The numerical models were able to capture the trends observed in the experimental tests, and good quantitative agreement between the experimental and predicted responses was in general obtained. One aim of this study is to provide high-precision experimental data, combined with a validated numerical modelling strategy, that can be used in simulation-based optimisation of sandwich panels exposed to blast loading.

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