Foot-Ground Interaction for 2D Gait Using Concurrent Optimization

2017 ◽  
Author(s):  
Yujiang Xiang ◽  
Benjamin Ramirez ◽  
Sarah Hoffman ◽  
Tonoy Chowdhury
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Reaction Force ◽  
Optimal Solution ◽  
Optimization Method ◽  
Inverse Optimization ◽  
Human Gait ◽  
Optimization Approach ◽  
Concurrent Optimization ◽  
Skeletal Model

Foot-ground interaction is modeled for a human gait simulation by using a 2D skeletal model with 12 degrees of freedom (DOF). Three contacting elements are attached to the heel, phalangeal, and toe sections respectively. The contacting process is modeled using an inverse optimization approach, in which the contacting force due to the penetration deformation and velocity is equal to the balanced ground reaction force (GRF). This is set as an equality constraint in the walking optimization formulation. A predictive dynamics approach is used to predict the walking motion and to optimize the contacting process. The results indicated that the contacting model can realistically match the GRF, and the resulting gait motion, contacting penetration, and contacting parameters are all optimized simultaneously. The optimal solution is obtained in seconds. This demonstrates an efficient way to model the foot-ground contacting deformation process using an inverse optimization method and eliminates the need for integrating equations of motion (EOM).

scholarly journals A two-stage evolutionary optimization approach for an irrigation system design

2016 ◽  
Vol 19 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Milan Cisty ◽  
Zbynek Bajtek ◽  
Lubomir Celar
Keyword(s):  
Water Distribution ◽  
Irrigation System ◽  
Optimal Solution ◽  
Water Distribution Network ◽  
Search Space ◽  
Optimization Method ◽  
Global Optimum ◽  
Optimization Approach ◽  
Nsga Ii ◽  
Irrigation Network

In this work, an optimal design of a water distribution network is proposed for large irrigation networks. The proposed approach is built upon an existing optimization method (NSGA-II), but the authors are proposing its effective application in a new two-step optimization process. The aim of the paper is to demonstrate that not only is the choice of method important for obtaining good optimization results, but also how that method is applied. The proposed methodology utilizes as its most important feature the ensemble approach, in which more optimization runs cooperate and are used together. The authors assume that the main problem in finding the optimal solution for a water distribution optimization problem is the very large size of the search space in which the optimal solution should be found. In the proposed method, a reduction of the search space is suggested, so the final solution is thus easier to find and offers greater guarantees of accuracy (closeness to the global optimum). The method has been successfully tested on a large benchmark irrigation network.

An Adaptive Self-Sensing Strategy for Piezoelectrically-Actuated Microcantilevers Used in Ultra-Small Mass Sensing Applications

2006 ◽  
Author(s):  
Miheer Gurjar ◽  
Nader Jalili
Keyword(s):  
Adaptive Estimation ◽  
Equations Of Motion ◽  
Optimization Method ◽  
The Self ◽  
Optimization Approach ◽  
Mass Sensing ◽  
Piezoelectric Patch ◽  
Sensing Applications ◽  
Tip Mass ◽  
Microcantilever Beam

This paper presents a mathematical model of a self-sensing microcantilever beam for mass sensing applications. Equations of motion are derived for a microcantilever beam with a tip mass and a piezoelectric patch actuator deposited on the cantilever surface. In the self-sensing mode, the same piezoelectric patch is used for actuation and sensing. Selfinduced voltage signals, which are extracted using a capacitive bridge mechanism, reveal frequency information of the vibrating beam, which in turn, reveals the particle mass. Equations of motion are obtained using the extended Hamilton's principle by considering the microcantilever as a distributed- parameters system. Two methods to estimate the unknown tip mass are presented. The first one is based on an inverse solution to the characteristic equation problem, while the second method uses a constraint-based optimization approach to estimate the tip mass. To improve the self-sensing performance, the need for adaptive estimation of the piezoelectric capacitance is stressed and an online estimation mechanism is presented. Simulations are presented to demonstrate the ability of the model to detect tip mass up to 0.1 femtogram (1 femtogram = 10-15 gm). Further simulation results demonstrate the working of constraint optimization method and adaptive self-sensing mechanism.

Multidisciplinary Design Optimization of Small Canister-Launched Space Launch Vehicle Using Genetic Algorithm

2013 ◽  
Vol 302 ◽  
pp. 583-588 ◽  
Author(s):  
Fredy M. Villanueva ◽  
Lin Shu He ◽  
Da Jun Xu
Keyword(s):  
Genetic Algorithm ◽  
Design Optimization ◽  
Multidisciplinary Design Optimization ◽  
Optimal Solution ◽  
Optimization Method ◽  
Launch Vehicle ◽  
Low Earth Orbit ◽  
Multidisciplinary Design ◽  
Optimization Approach ◽  
Design Variables

A multidisciplinary design optimization approach of a three stage solid propellant canister-launched launch vehicle is considered. A genetic algorithm (GA) optimization method has been used. The optimized launch vehicle (LV) is capable of delivering a microsatellite of 60 kg. to a low earth orbit (LEO) of 600 km. altitude. The LV design variables and the trajectory profile variables were optimized simultaneously, while a depleted shutdown condition was considered for every stage, avoiding the necessity of a thrust termination device, resulting in reduced gross launch mass of the LV. The results show that the proposed optimization approach was able to find the convergence of the optimal solution with highly acceptable value for conceptual design phase.

Three-Dimensional Symmetric Maximum Weight Lifting Prediction

2020 ◽  
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Degrees Of Freedom ◽  
Material Handling ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Weight Lifting ◽  
Optimization Approach ◽  
Maximum Weight ◽  
Manual Material Handling ◽  
Reaction Forces ◽  
Skeletal Model

Abstract Lifting heavy weight is one of the main reasons for manual material handling related injuries which can be mitigated by determining the limiting lifting weight of a person. In this study, a 40 degrees of freedom (DOFs) spatial skeletal model was employed to predict the symmetric maximum weight lifting motion. The lifting problem was formulated as a multi-objective optimization (MOO) problem to minimize the dynamic effort and maximize the box weight. An inverse-dynamics-based optimization approach was used to determine the optimal lifting motion and the maximum lifting weight considering dynamic joint strength. The predicted lifting motion, ground reaction forces (GRFs), and maximum box weight were shown to match well with the experimental results. It was found that for the three-dimensional (3D) symmetric lifting the left and right GRFs were not same.

Solid Rocket Motor Design Optimization Using Genetic Algorithm

2014 ◽  
Vol 905 ◽  
pp. 502-506 ◽  
Author(s):  
Fredy M. Villanueva ◽  
Lin Shu He ◽  
Da Jun Xu
Keyword(s):  
Genetic Algorithm ◽  
Design Optimization ◽  
Optimal Solution ◽  
Optimization Method ◽  
Rocket Motor ◽  
Design Parameters ◽  
Optimization Approach ◽  
Solid Rocket Motor ◽  
Conceptual Design Phase ◽  
Solid Rocket

A design optimization approach of a solid propellant rocket motor is considered. A genetic algorithm (GA) optimization method has been used. The optimized solid rocket motor (SRM) is intended to use as a booster of a flight vehicle, and delivering a specific payload following a predefined prescribed trajectory. Sensitivity analysis of the optimized solution has been conducted using Monte Carlo method to evaluate the effect of uncertainties in design parameters. The results show that the proposed optimization approach was able to find the convergence of the optimal solution with highly acceptable value for conceptual design phase.

Muscle Force Prediction of 2D Gait Using Predictive Dynamics Optimization

2016 ◽  
Author(s):  
Yujiang Xiang
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Force ◽  
Optimal Solution ◽  
Human Motion ◽  
Human Gait ◽  
Predictive Dynamics ◽  
Physical Constraints ◽  
Reaction Forces ◽  
Muscle Groups ◽  
Optimization Schemes

Cyclic human gait is simulated in this work by using a 2D musculoskeletal model with 12 degrees of freedom (DOF). Eight muscle groups are modeled on each leg. Predictive dynamics approach is used to predict the walking motion. In this process, the model predicts joints dynamics and muscle forces simultaneously using optimization schemes and task-based physical constraints. The results indicated that the model can realistically match human motion, ground reaction forces (GRF), and muscle force data during walking task. The proposed optimization algorithm is robust and the optimal solution is obtained in seconds. This can be used in human health domain such as leg prosthesis design.

An Optimization Method for Solution Selection Based on the Inverse Kinematics Problem of a Mechanical Arm

2015 ◽  
Vol 740 ◽  
pp. 211-217
Author(s):  
Yuan Yuan Luo ◽  
Dong Xu Li ◽  
Cai Zhi Fan
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Optimal Solution ◽  
Optimization Method ◽  
Target Object ◽  
Operation Process ◽  
Inverse Kinematics Problem ◽  
Simulation And Experiment ◽  
Solution Selection ◽  
Solution Problem

The solution selection problem of inverse kinematics for a mechanical arm is an important factor affecting the robot end effector positioning. This paper takes a real robotic arm of four degrees of freedom grasping the target object as the research background and studies the multi-solution problem of the inverse kinematics. Firstly, the paper establishes the kinematics model of the mechanical arm and solved the inverse kinematics equation by multiplying by the inverse of the coordinate transformation matrix on both sides. Secondly, the paper presents an optimization method based on joint minimization aiming at the multi-solution problem, and deals with the singularity of the mechanical arm by using the method of setting threshold in the process of operation, which can get the optimal solution without suffering singularity problems. Finally, the simulation and experiment results show that the joint angle of the mechanical arm changes smoothly during the operation process and singular points do not occur, verifying the effectiveness of the processing method.

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

The Influence of Loading Position in A Priori High Stress Detection using Mode Superposition

2020 ◽  
Vol 1 (1) ◽  
pp. 93-102
Author(s):  
Carsten Strzalka ◽  
◽  
Manfred Zehn ◽  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
A Priori ◽  
High Stress ◽  
Von Mises Stress ◽  
Detailed Knowledge ◽  
Variable Loading ◽  
Numerical Effort ◽  
Von Mises

For the analysis of structural components, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent durability analyses. In industrial application advanced FE-models result in high numbers of degrees of freedom, making dynamic analyses time-consuming and expensive. As detailed finite element models are necessary for accurate stress results, the resulting data and connected numerical effort from dynamic stress analysis can be high. For the reduction of that effort, sophisticated methods have been developed to limit numerical calculations and processing of data to only small fractions of the global model. Therefore, detailed knowledge of the position of a component’s highly stressed areas is of great advantage for any present or subsequent analysis steps. In this paper an efficient method for the a priori detection of highly stressed areas of force-excited components is presented, based on modal stress superposition. As the component’s dynamic response and corresponding stress is always a function of its excitation, special attention is paid to the influence of the loading position. Based on the frequency domain solution of the modally decoupled equations of motion, a coefficient for a priori weighted superposition of modal von Mises stress fields is developed and validated on a simply supported cantilever beam structure with variable loading positions. The proposed approach is then applied to a simplified industrial model of a twist beam rear axle.

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