An Active Foot-Ankle Prosthesis With Biomechanical Energy Regeneration

2010 ◽  
Vol 4 (1) ◽  
Author(s):  
Joseph K. Hitt ◽  
Thomas G. Sugar ◽  
Matthew Holgate ◽  
Ryan Bellman
Keyword(s):  
Design Methodology ◽  
Energy Requirement ◽  
System Modeling ◽  
Model Verification ◽  
Ankle Prosthesis ◽  
Below The Knee ◽  
Actuation System ◽  
Transtibial Prosthesis ◽  
Power And Energy ◽  
Good Agreement

A unique, robust, robotic transtibial prosthesis with regenerative kinetics was successfully built and a 6-month human subject trial was conducted on one male below-the-knee amputee under linear walking conditions. This paper presents the quasistatic system modeling, DC motor and transmission modeling and analyses, design methodology, and model verification. It also outlines an approach to the design and development of a robotic transtibial prosthesis. The test data will show that the true power and energy requirement predicted in the modeling and analyses is in good agreement with the measured data, verifying that the approach satisfactorily captures the physical system. The modeling and analyses in this paper describes a process to determine an optimal combination of motors, springs, gearboxes, and rotary to linear transmissions to significantly minimize the power and energy consumption. This kinetic minimization allows the downsizing of the actuation system and the battery required for daily use to a self-portable level.

Missile Roll Autopilot Redesign Based Advanced Fin Actuation System Modeling

2020 ◽  
Author(s):  
Sameh Fathey Shelan ◽  
Mohammed Abozied Hassan ◽  
Hossam Hendy ◽  
Yehia Zakarya Elhalwagy
Keyword(s):  
System Modeling ◽  
Actuation System

scholarly journals Preliminary Design of a Small Unmanned Battery Powered Tailsitter

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Bo Wang ◽  
Zhongxi Hou ◽  
Zhaowei Liu ◽  
Qingyang Chen ◽  
Xiongfeng Zhu
Keyword(s):  
Energy Consumption ◽  
Design Methodology ◽  
Design Space ◽  
Preliminary Design ◽  
Wing Loading ◽  
Detailed Design ◽  
Discharge Model ◽  
Battery Discharge ◽  
Power And Energy

This paper presents a preliminary design methodology for small unmanned battery powered tailsitters. Subsystem models, including takeoff weight, power and energy consumption models, and battery discharge model, were investigated, respectively. Feasible design space was given by simulation with mission and weight constraints, while the influences of wing loading and battery ratio were analyzed. Case study was carried out according to the design process, and the results were validated by previous designs. The design methodology can be used to determine key parameters and make necessary preparations for detailed design and vehicle realization of small battery powered tailsitters.

scholarly journals High Temperature, Permanent Magnet Biased, Fault Tolerant, Homopolar Magnetic Bearing Development

2008 ◽  
Author(s):  
Alan Palazzolo ◽  
Randall Tucker ◽  
Andrew Kenny ◽  
Kyung-Dae Kang ◽  
Varun Ghandi ◽  
...  
Keyword(s):  
High Temperature ◽  
Design Methodology ◽  
Permanent Magnets ◽  
Fault Tolerant ◽  
State Of The Art ◽  
Magnetic Bearing ◽  
Test Results ◽  
Test Rig ◽  
Control Forces ◽  
Good Agreement

This paper summarizes the development of a magnetic bearing designed to operate at 1,000F. A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1,000F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces with over one-half of the coils failed. The construction and design methodology of the bearing is outlined and test results are shown. The agreement between a 3D finite element, magnetic field based prediction for force is shown to be in good agreement with predictions at room and high temperature. A 5 axis test rig will be complete soon to provide a means to test the magnetic bearings at high temperature and speed.

A Quantitative Model of Surface Segregation in III-V Ternary Compounds

2000 ◽  
Vol 618 ◽  
Author(s):  
Sergey Yu. Karpov ◽  
Yuri N. Makarov
Keyword(s):  
Surface Segregation ◽  
Quantitative Model ◽  
Model Verification ◽  
Key Factors ◽  
Underlying Assumption ◽  
Factors Affecting ◽  
Surface Population ◽  
Theoretical Predictions ◽  
Good Agreement ◽  
Crystal Bulk

ABSTRACTA quantitative model of surface segregation free from adjustable parameters is suggested for the growth of ternary III-V compounds. In contrast to previous approaches, the model considers the dynamics of surface population by the three elements producing the ternary alloy. The underlying assumption is that the atoms in the adsorption layer are in equilibrium with the crystal bulk. Elastic strain arising in the epitaxial layer due to the lattice constant mismatch with the substrate is found to be one of the key factors affecting segregation. Along with growth temperature, it controls the segregation efficiency and the composition profile evolution in a growing heterostructure. The effect of the V/III ratio, growth rate and other parameters is accounted for. Here, we apply the model to analyze the InGaAs growth by molecular beam epitaxy owing to the vast experimental data available for the model verification. The theoretical predictions show a good agreement with the experimental observations

The estimation of the length constant of a long cooling fin by variational iteration method

2015 ◽  
Vol 25 (4) ◽  
pp. 887-891 ◽  
Author(s):  
Yan Zhang ◽  
Qiaoling Chen ◽  
Fujuan Liu ◽  
Ping Wang
Keyword(s):  
Nonlinear Equation ◽  
Nonlinear Equations ◽  
Iteration Method ◽  
Design Methodology ◽  
Variational Iteration Method ◽  
Engineering Problem ◽  
Content Type ◽  
Variational Iteration ◽  
Length Constant ◽  
Good Agreement

Purpose – The purpose of this paper is to validate the variational iteration method (VIM) is suitable for various nonlinear equations. Design/methodology/approach – The He’s VIM is applied to solve nonlinear equation which is derived from actual engineering problem. The result was compared with other method. Findings – The result obtained from VIM shows good agreement with Xu’s result which provide a solid evidence that VIM is convenient and effective for solving nonlinear equation in the engineering. Originality/value – The VIM can be extended to many academic and engineering fields for nonlinear equations solving.

The reaction of aluminum atoms with methane

1990 ◽  
Vol 68 (4) ◽  
pp. 633-639 ◽  
Author(s):  
Hengtai Yu ◽  
John D. Goddard
Keyword(s):  
Transition State ◽  
Energy Barrier ◽  
Energy Requirement ◽  
Basis Sets ◽  
Insertion Reaction ◽  
Reaction Coordinates ◽  
Abstraction Reaction ◽  
Level Transition ◽  
Split Valence ◽  
Good Agreement

Abinitio SCF and CISD calculations with split valence and larger basis sets have been carried out for several possible reactions of ground state (2P) aluminum atoms with methane. In particular, the barriers to insertion of Al into a CH bond to give a CH3AlH intermediate and the abstraction of a hydrogen by Al to give AlH and CH3 have been studied. At the SCF level, transition state structures have been located and verified by vibrational analyses. In addition, intrinsic reaction coordinates (IRC) have been followed from the transition state geometries down to reactants and to products. Calculated vibrational frequencies and lowest excitation energy for the CH3AlH intermediate are in good agreement with matrix isolation experimental results. As anticipated on the basis of MO natural correlation symmetry arguments, the energy barrier to the insertion reaction is high (~50 kcal mol−1 at the CI level). The energy requirement for the abstraction reaction is similar.[Formula: see text]Keywords: Al, CH4, HAlCH3, insertion and abstraction reactions.

Finite-Element Modeling and Model Verification of Steel W-Beam Guardrails Subject to Pendulum Impact Loading

1998 ◽  
Vol 1647 (1) ◽  
pp. 147-157
Author(s):  
T. Russell Gentry ◽  
Lawrence C. Bank
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
Model Verification ◽  
Federal Highway ◽  
Time Histories ◽  
Tension Capacity ◽  
The Impact ◽  
Impact Events ◽  
Pendulum Impact ◽  
Good Agreement

The experimental and simulated response of steel W-beam guards to pendulum impact loading for impact velocities of 20 km/h, 30 km/h, and 35 km/h are presented. The guardrails were supported by four posts and cable-anchored at each end to ensure that the full tension capacity of the rail could be developed. Experiments carried out with a 912-kg impact pendulum are compared with LS-DYNA finite-element simulations of the impact events. Pendulum tests were completed at the Turner Fairbank Highway Research Center of the Federal Highway Administration. Acceleration, velocity, and displacement time histories are compared for the pendulum impact test and the LS-DYNA simulations. Comparison of the experimental and simulation acceleration records is made using the Numerical Analysis of Roadside Design time-domain statistics. The comparative statistics show that the simulations are in good agreement with the experiments. Guardrail tension data and cable tension data are presented from the LS-DYNA simulations. Results show that the guardrail was close to its tension yield point when impacted an initial velocity of 35 km/h.

scholarly journals Application and Verification of a three-dimensional Hydrodynamic Model to Hamilton Harbour, Canada

2013 ◽  
Vol 2 (1) ◽  
pp. 77-89
Keyword(s):  
Water Level ◽  
Hydrodynamic Model ◽  
Three Dimensional ◽  
Model Verification ◽  
Water Current ◽  
Trajectory Model ◽  
Hamilton Harbour ◽  
Water Level Changes ◽  
Model Predictions ◽  
Good Agreement

A multi-layered three-dimensional hydrodynamic model has been developed to provide flow fields and water level changes in Hamilton Harbour. The field data collected in Hamilton Harbour during 1990 & 1991 field seasons was used for model verification. The simulated currents were compared with current meter data. Results from the trajectory model are in good agreement with the drogue experimental data. A quantitative criterion to evaluate the trajectory comparison was established with the help of the trajectory model using the random-walk approach. By using the water level changes in the Burlington Ship Canal, the model predictions were validated with the measurements at three water level stations in the Harbour. These comparisons demonstrate that the models can simulate the major features of the water current and level changes in Hamilton Harbour.

A Symmetric Multichamber Hydraulic Cylinder with Variable Piston Area: An Approach to Compact and Efficient Electrohydrostatic Actuation

2020 ◽  
pp. 1-35
Author(s):  
Harrison Bartlett
Keyword(s):  
Design Methodology ◽  
Hydraulic Cylinder ◽  
Power Losses ◽  
Symmetry Constraint ◽  
Standard Methods ◽  
Motor Torque ◽  
Actuation System ◽  
Constant Area ◽  
Hydraulic Cylinders ◽  
Simulation Results

Abstract This paper presents an approach for designing symmetric (effective cylinder area during extension is the same as that during retraction) multichamber cylinders with discretely variable piston area. The design methodology is presented in a generalizable manner and is demonstrated on an example five chamber cylinder design. A method for finding symmetric multichamber cylinder configurations from a given cylinder topology is presented, and subsequently, a method for discretely varying the effective piston area is developed, subject to a cylinder symmetry constraint. Furthermore, an algorithm is presented to optimally switch the effective cylinder area of an electrohydrostatic actuation system either to minimize the magnitude of motor torque or to minimize resistive power losses in the system. Additionally, a method for optimizing standard (constant area) hydraulic cylinders to minimize motor torque magnitude or resistive power losses is presented. These methods are then demonstrated on an example electrohydrostatic actuation system via simulation. Results indicate that this multichamber cylinder approach with discretely variable piston area may allow for the design of compact and efficient actuators relative to standard methods.

Mechanical Redesign of a Transtibial Prosthesis With Active and Passive Components and a Four-Bar Mechanism

2020 ◽  
Author(s):  
Devon K. Plata ◽  
Jessica B. Thayer ◽  
Philip A. Voglewede
Keyword(s):  
Energy Expenditure ◽  
Energy Input ◽  
Impedance Control ◽  
Energy Requirement ◽  
Neutral Position ◽  
Passive Components ◽  
Input Configuration ◽  
Transtibial Prosthesis ◽  
Spring Mechanism

Abstract This paper proposes a redesign of a four-bar mechanism for an active transtibial prosthesis created by Bergelin 2010 and modified by Klein 2009. Bergelin utilized a four-bar mechanism, motor, and spring to match the prosthesis ankle moments to the ankle moments of a healthy ankle. Bergelin’s prosthesis did succeed in matching ankle moments closely, but with excessive motor energy expenditure when the prosthesis was in a neutral position. Klein proposed a redesign of the mechanism to change the motor-spring connection from parallel to series to eliminate the energy requirement when the device is in neutral position, which allowed for the application of impedance control of mechanism. This paper proposes a reoptimization of the series motor-spring mechanism configuration proposed by Klein, which further reduces the energy input configuration of the active prosthesis.

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