Alexandru Margine

Mechanism of a Leg Exoskeleton for Walking Rehabilitation Purposes

This paper addresses attention to the conceptual mechanism design of a leg exoskeleton for human rehabilitation purposes. Different mechanism solutions for locomotion rehabilitation are analyzed from a structural and functional viewpoints. By using mobility analysis and considerations on structure design, a new leg exoskeleton is identified with low-cost features and motion ability for rehabilitation purposes.

Design and Simulation of a Single DOF Human-Like Leg Mechanism

In this paper is carried out the selection and simulation of a one degrees of freedom (DOF) leg mechanism. The leg mechanism consist of a nine bar linkage and is based on a Low-cost Easy-operation idea. Virtual simulation tests of the model shows the feasible of the proposed leg mechanism, for human leg motion assistance. Kinematics and dynamics analysis of the leg mechanism is carried out. Finally, dynamic simulation results reveal the motion characteristics and performance of the leg mechanism.

Kinematic and Dynamic Study of a Mechanism for a Vehicle Front and Rear Stabilizer Bars

In this paper, a method is described for theoretical and experimental studies of a front and rear stabilizer bars used on vehicle steering and suspension systems. Based on the fatigue experimental tests performed on a special test-bed, a complex actuation mechanism from the test bed structure will be analyzed. This mechanism through his kinematic and dynamic structure assures complete conditions for simulating the dynamic behavior in a complex mode of the rear stabilizer bar used on a vehicle steering and suspension structures.

Modular Knee Orthosis FEM Analysis from Kinematic Considerations

In this paper a locomotion system kinematic analysis is presented in order to obtain the knee motion equations for a child walking. With these equations a modular knee orthosis with flexible elements was designed and simulated through finite elements analysis with ADAMS. The whole human locomotion system is analyzed. Based on these results a modular knee orthosis prototype for a 7 years old child with locomotion disabilities was fabricated. The prototype was evaluated through experimental tests with CONTEMPLAS motion analysis equipment.

Study upon the Dynamic Answer of Plane Manipulators

The paper illustrates the structure of plane mechanical systems used to manipulators. In the first part are presented some kinematics schemes used to plane manipulators. These mechanisms are used to manipulators, positioning and control systems. In generally these mechanisms have two or three degree of mobility. The purpose of the paper is to study the dynamics of a plane manipulator mechanical system used to manipulate garbage containers. It is presented the kinematics scheme of a plane manipulator, used to this purpose and is presented the mechanism functional description. In the second part is presented the kinematical and dynamical analysis for the plane manipulator mechanism. In the last part of the paper are presented graphical results for the dynamics parameters.

Analytical and Numerical Study of Critical Speed for Right Shafts

In this paper it is presented the theoretical, experimental and numerical simulation of critical speed for right shafts. For this purpose, it is designed a virtual model of a test bench for shaft critical speed analysis. The studied shaft is mounted on two bearings and on the middle it has mounted a heavy disc. The system has the possibility to modify the shaft speed with a frontal friction continuous variable transmission. It is presented a mathematical model to calculate the critical speed of the shaft. The result obtained by analytical calculation is verified by experimental way and by numerical simulation. The simulation of shaft flexibility is achieved in ADAMS multibody software and obtained results are presented and discussed. Shaft experimental flexional deformations and the results obtained by numerical simulation are similar. Study of shaft flexibility by numerical simulation in ADAMS is an easy tool and very important for practical application to avoid resonance in elastic mechanical systems.

Children Locomotion Rehabilitation Test Bed Designed from Kinematic Considerations

In this paper a locomotion system kinematic analysis is presented in order to obtain the hips, knees and ankles motions equations for a child walking. With these equations an experimental test bed was especially designed and simulated for locomotion rehabilitation by using MSC Adams. The whole human locomotion system was analyzed from kinematic viewpoints. Based on the obtained results a locomotion rehabilitation test bed prototype for a 7 years old child with locomotion disabilities was fabricated.

Experimental Investigations Concerning Friction from Threaded Assemblies

In this research an experimental test rig and method to measure friction torque from screw-nut assemblies is presented. The experimental test rig uses to measure friction torque an elastic cylinder bush with strain gauge transducers. The frictions torque and the traction force from the threaded assembly are transmitted to the elastic cylinder bush and produce elastic deformations. The elastic cylinder is calibrated in order to establish a correlation between elastic deformation and force of solicitation. In order to measure the experimental data the MGCPlus data acquisition system is used. The experimental results obtained are presented, consisting in the dependence between friction torques and axial traction force occurred in the screw.

Experimental Approach Regarding the Behavior of a Human Rehabilitation Exoskeleton

In this paper an experimental research was performed in case of a human rehabilitation exoskeleton. The research aim was to evaluate the joint trajectories and the influence of the ground-foot contact by using two distinctive shapes of the exoskeleton foot. Thus an experimental motion analysis was used, called CONTEMPLAS and an exoskeleton prototype with 1DOF placed on a treadmill. The experimental activity was developed when the exoskeleton was used on walking activity. There were studied two types of foot shapes and also the generated impact of their form on the hip, knee and ankle joints trajectories during walking. The obtained results will be useful for the improvement of the exoskeleton orientation in space.

MOTION STUDY OF A WHEELCHAIR PROTOTYPE FOR DISABLED PEOPLE

In this paper is presented the design and experimental prototype of a wheelchair for disabled people. Design solution proposed to be implemented uses two reduction gears motors and a mechanical transmission with chains. The motion controller developed uses PWM technology (pulse wave modulation). The wheelchair has the ability of forward – backward motion and steering. The design solution is developed in Solid Works, and it’s implemented to a wheelchair prototype model. Wheelchair design and motion makes him suitable especially for indoor use. It is made a study of the wheelchair kinematics, first using a kinematic simulation in Adams. Are presented the wheelchair motion trajectory and kinematics parameters. The experimental prototype is tested with a motion analysis system based on ultra high speed video recording. The obtained results from simulation and experimentally tests, demonstrate the efficiency of wheelchair proposed solution.