Daniela Tarnita

Numerical Simulations and Experimental Human Gait Analysis Using Wearable Sensors

The paper presents a comparison between an experimental study of flexion-extension movement in human legs joints and numerical simulations on a virtual mannequin computed in ADAMS virtual environment. Using Biometrics system which is a data acquisition system based on electrogoniometers, data were collected for the right and left ankle, knee and hip during experimental gait overground on force platforms. The mean flexion-extension cycles for legs joints were obtained. The obtained experimental data series were be introduced as input data in the joints of the virtual mannequin and a walking simulation was performed in ADAMS environment software. The variation of ground forces during walking are obtained by experimental data and by virtual simulation.

Contributions on the Modeling and Simulation of the Human Knee Joint with Applications to the Robotic Structures

The main objective of this chapter is to develop a three-dimensional solid finite element model of the healthy knee joint to predict stresses in its individual components and to study the effects of the frontal plane tibio–femoral angle on the stress distribution in the knee cartilages and menisci. It was developed the geometric models of the joint which shows different tilt in varus and valgus with 5°, the joint being affected by osteoarthritis in the medial and lateral compartment. For geometric modeling of the human knee joint was used the embedded applications: Design Modeler, SpaceClaim under Ansys Workbench 14.5 software package. For each model a non-linear analysis was performed. The non-linearities are due to the presence of the contact elements modeled between components surfaces. The applied force was equal with 800 N. Finally the results obtained for normal knee and for OA knee joint are compared.

Design and Simulation of an Orthotic Device for Patients with Osteoarthritis

The first aim of this paper is the development of a virtual model of a new orthotic device, starting from an existent orthotic device, currently used in knee rehabilitation and from the virtual models developed for healthy knee joint and for the knee joint affected by osteoarthritis (OA) disease with varus inclination of 5°, 10°, 15°. The second aim consists in the obtaining of stress and displacements using numerical simulations for healthy knee joint, for knee joint affected by osteoarthritis (OA) and for orthotic device—OA knee assemblies. The Finite Element Method (FEM) is used to obtain the diagrams and the maximum values of von Mises stress and displacements for healthy knee, for the three studied cases of OA knee, orthotic devices-assemblies. These values are extracted and compared. Finally, an experimental study is provided in order to compare the range of motion and the amplitude of the flexion-extension knees of a five patients group with OA knees with and without orthosis, and to mark out the advantages of the proposed orthotic device.

Application of Nonlinear Dynamics to Human Knee Movement on Plane and Inclined Treadmill

The objective of this study is to quantify and investigate nonlinear motion of the human knee joint for a sample of 7 healthy subjects on plane treadmill and inclined treadmill with an angle of 10° and for both knees of a sample of 3 patients who suffer of osteoarthritis, only on the plane treadmill, using nonlinear dynamics stability analysis. The largest Lyapunov exponent (LLE) and correlation dimensions are calculated as chaotic measures from the experimental time series of the flexion-extension angle of human knee joint. Larger values of LLEs obtained for patients group suffering by osteoarthritis are associated with more divergence and increase of knee variability, while smaller values obtained for healthy subjects reflect increase of local stability, less divergence and variability, less sensitivity to perturbations and higher resistance to stride-to-stride variability. The use of nonlinear tools may provide additional insight on the nature of the step-to-step fluctuations present in human and robotic locomotion.

Influences of Varus Tilt on the Stresses in Human Prosthetic Knee Joint

In this paper the effects of varus tilt on contact stresses in the three components of total knee prostheses using 3D finite element analysis were investigated. Using Ansys simulation environment, six complex virtual models of human knee joint–prosthesis assembly obtained for six different varus tilts which increase from 176o to 191o, with an increment of 3o have been subjected to finite element analysis in order to obtain the stress maps and total displacements maps.

Experimental Bench Used to Test Human Elbow Endoprosthesis

In this paper, the 3D virtual model and the prototype of an experimental bench designed and used to test endoprosthesis prototypes for elbow joint in flexion-extension and pronation-supination movements are presented. The experimental tests were carried out on a group of nine healthy subjects and on the corpse prosthetic elbow. Experimental data for flexion-extension movement cycles were acquired using SimiMotion video system. The data files and the flexion-extension angle diagrams are obtained for all the subjects and for the corpse prosthetic elbow. The command programs in C++ for the performance of experimental tests on the bench are elaborated. A comparative experimental study of flexion-extension movement for healthy elbows and for the prosthetic corpse elbow joint fixed on the experimental bench is presented.

Modeling, Simulation and Optimization of a Human Knee Orthotic Device

In order to improve the quality of human walking, the present paper is analyzing a 3D virtual model for an orthotic device which is subjected to an optimization process based on dimensional, geometric and material criteria. For geometric modeling of the human knee joint were used the embedded applications: DesignModeler, SpaceClaim under AnsysWorkbench software package and for the orthotic device it was used ProEngineer application. The orthotic device is designed to rehabilitate people with knee problems, especially for the osteoarthritis affection. The geometric model of the joint shows a 50 tilt in varus, the joint beeing affected by osteoarthritis in the medial compartment. Using Ansys simulation environment, the virtual assembly joint orthois has been subjected to a nonlinear analysis based on the contacts and on the materials used. The proposed orthotic device seeks to improve the quality of walking by minimizing the loads from the knee joint, also on cartilage and on the menisci. Finally there are beeing compared the results obtained for normal knee, OA knee and OA knee-orthosis assemblies.

Nonlinear Analysis of Human Ankle Dynamics

In this paper finite-time Lyapunov exponents were estimated in order to quantify the local dynamic stability, based on the experimental time series of the flexion-extension and inversion-eversion angles of ankle joints, obtained from a group of five subjects with normal left ankles and right ankles suffering by repeated sprains with residual laxities walking over-ground and on plane and inclined treadmill with different speeds and inclinations.

Design and Finite Element Analysis of a New Spherical Prosthesis-Elbow Joint Assembly

This study aims to present a new virtual model of an elbow prosthesis with as few components as possible, having a simpler technological approach which can be an important base for the study of the complex behavior of the elbow joint. The prosthetic system is of spherical type consisting of three parts: a part implanted in the humerus, a part implanted in the ulna bone and a third part transforms the assembly from an unconstrained prosthesis in a semi-constrained prosthesis. The kinematic simulation of the flexion-extension and pronation-supination movements of the spherical prosthesis—joint assembly was performed. The virtual model is designed in Solid Works software. By using the finite element method, the healthy elbow joint and the prosthetic elbow joint assembly were analysed and the comparative diagrams of the maximum stress in healthy elbow joint and in prosthetic elbow joint concerning the flexion-extension and pronation-supination movements were drawn and analysed.

Experimental Human Walking and Virtual Simulation of Rehabilitation on Plane and Inclined Treadmill

The paper presents the results of the authors concerning the experimental human walking and numerical simulation of human rehabilitation on a treadmill. Using Biometrics data acquisition system based on electrogoniometers, experimental measurements for ankle, knee and hip joints of right and left legs during walking on plane and inclined treadmill are performed. The human legs motion assistance for rehabilitation is proposed with an attached exoskeleton. The numerical simulation of a virtual mannequin walking with the attached exoskeleton on a plane and inclined treadmill is performed, using ADAMS virtual environment. A comparison between human experimental measurements and numerical simulations of a virtual mannequin with exoskeleton is presented.