Violeta Cristina Dumitru

Design and Motion Analysis of a Powered Wheelchair

This paper presents researches developed by authors to design a motorized robotic wheelchair for disabled people. These devices enable disabled people perform many activities of daily living thus improving their quality of life. Proposed solution uses for traction one DC motor with steps adjustable angular speed, and for steering one smaller motor. It is presented the kinematic scheme of the proposed transmission and kinematic analysis. It is developed a CAD model of the transmission, mounted on a wheelchair. They are made simulation in Adams, in order to verify the functionality of the proposed transmission. The obtained results validate proposed transmission model and enable success implementation of this transmission to a wheelchair experimental model.

The Behavior of the Virtual Human Head-Neck System during the Main Movements

The subject of this paper permits the cooperation between many researchers which activate in different fields, which have the capacity to develop informational methods and technologies to solve difficult problems given by the complexity of the scientifically target. Using computer-aided design (CAD) and dynamic simulation programs was developed a virtual model of the cervical human spine that includes the main muscle groups simulated by springs with dynamic parameters, nonlinear and variable. Were studied the main types of movements (displacements) lateral bending (left-right) and flexion-extension movements.

Mechanical and Corrosion Tests on Iron-Based Reinforced Parts Obtained by Powder Metallurgy

Samples from high compressibility powders (Ancorsteel 1000B) obtained by pressing at different pressures and sintering at 1150 °C, with (IPASW) and without spring steel wire (Φ = 0.5 mm) reinforcement (IPAS), coated and uncoated with zinc samples were selected for study of corrosion behaviour in salt spray and were subjected to mechanical tests (tensile strenght).

Economical Model Based on Graph Theory for Optimization Execution Order of Automotive Products on the Manufacturing Lines Served by Robots

This paper presents an economic model based on graph theory to optimize the execution order for automotive products on the manufacturing lines served by robots, so that the total manufacturing cost is minimized. The starting point is a representation of the range of automotive products with similar design attributes but with different construction requirements (material, tolerances, production volume). This representation is distinguished by a directed graph G = (X, Γ) consisting of the set X of nodes (products) and the set Γ of arcs (paths with minimal cost). In terms of mathematical optimization problem is solved by determining the minimum length Hamiltonian path in the graph, using the algorithm of Foulkes. The length of a path is obtained by adding the numbers associated with that path arcs. The model can be applied to other extreme transportation issues CIM type, such as: transportation network modeling; determining minimum distances; median problem (placing checkpoints); multi-product maximum flow problem.

Study Regarding the Specific Components Performance of Assistant Robots

This paper presents a comparative study regarding the specific components from thermoplastic polymers and ceramic powders for a assistant robot. Experimental research targets the testing of these materials in order to optimize the vertebrae of the robot. The vertebrae are part of a miniature robot (size, weight) for exploration and interventions in a limited space. The simplicity and small size are advantageous for reliability, safety, fast installation and ease of use. Knowing the friction coefficient shows a great importance, particularly in the friction coupling in which movement occurs with low speeds.

Evaluation and Improvement of Performance Parameters for a Mechanical System Used in Minirobotics

The concept, design and construction of mechanical systems performance is limited by the ranges prescribed for different performance parameters (size, accuracy, repeatability, quality, safety, and cost). The aim of the research is to evaluate and improve the performance parameters for a mechanical system with multiple vertebrae drive by wire, to perform functions of exploration, inspection and intervention in limited space environments (anatomical). New mechanical structure contains modules that allow changing the work parameter and the algorithms to control the location (position, orientation) of the end effector. Sensory system can be configured depending on the product and the program chosen, embracing suitable position, bending and strength sensors. Error compensation by a feedback process has become the most economical solution and easier to apply. Rigidity functions and bending forces resolution are presented along with a simulation of robotic arm positions for all vertebrae. The results demonstrate the capability of this system to perform precise movements to an imposed target.

Application of the FMEA Concept to Medical Robotic System

This paper examines the potential risks for the design and manufacture products for medical robotics using FMEA method. So we researched all foreseeable potential defects and their causes and effects for a robotic arm. The product is decomposed into components / functions and researched on the requirements for construction, namely the preservation of these requirements during production. Through a qualitative assessment of the effect of a defect, the probability of occurrence and probability of detection were discovered risks and set appropriate corrective measures. Thus FMEA is an effective method of preventive quality assurance.

Mechatronic System with Applications in Medical Robotics

This paper studies the dynamic analysis of a multi-articulated mechanical system actuated by elastic cables, for a complete cycle of operation. The multi-articulated mechanical system consists of two kinematic chains, one interior and the other one exterior. The kinematic chains build a mechanical structure for a multi-articulated robotic system. The robot tended to be used in minimally invasive surgery. The motion of the system is obtained by overlapping the rigid body movement with the elastic one. The dynamic analysis was made possible by building a model and virtual prototyping model.

Techniques, Methods and Instruments for Human Bone Virtual Re-Construction - Main Human Movements Simulations

To understand the problems, which appear in every human joint, it is very important to know the anatomy and morphology of the human bones and the way in which the components are working together to realize a normal functionality.For this purpose was used a CAD parametric software which permits to define models with a high degree of difficulty. First, it was used a CT or MRI device to obtain the parallel sections in the studied component bone. A 3D scanner can be used only for the outer geometry. In the second step, the images were transferred to a 2D CAD software, as AutoCAD, where the outer and inner contours of the bone were approximate to polygonal lines composed by many segments. After this, the contours were transferred to a 3D CAD software, as SolidWorks, where, step by step, and section by section, was defined the virtual bone component. The primary sections can be directly unified in shapes, as Loft geometrical shape, to define the base of the bone. Additionally to this shape can be attached other Loft, Round or Dome shapes. For some components, as vertebrae, mandible or skull bones, it can be used a preliminary model obtained by parallel sections. Starting from this, the model can be defined using the main 3D curves for final virtual solid model.The virtual model of the bones can be used for different simulations for human movements as walking, flexion, extension, rotation, lateral bending. Also, parts of the entire human bone system were be used for implant, surgery and prosthesis simulation, virtual and rapid prototyping.

Modular System for Testing the Performance of Poly-Articulate Robotic Structures

This paper presents a modular system for testing the performance of a poly-articulate robotic arm (snake like) with the push-pull actuation redundancy. Mechanical structure contains modules that allow testing of robots with different structures of the robotic arm (discrete hyper-redundant, continuous). Sensory system can be configured depending on the product and testing program adapting the sensors of position, velocity, time and vibrations. The monitoring system developed allows the automatic calibration of actuators and sensors, data and signal acquisition.