Georgeta Ionascu

Influence of technological parameters on the dynamic behavior of a MEMS accelerometer

The paper deals with studying the mechanical structure of a bulk-micromachined silicon piezoresistive accelerometer by using FEM (Finite Element Method). The vibration modes (resonant frequencies) and sensitivity were predicted. The results of numerical simulation, validated experimentally have pointed out the influence of manufacturing process parameters on the accelerometer performance.

Manufacturing and testing technology for a silicon piezoresistive microaccelerometer

This paper deals with, the manufacturing technology by silicon bulk micromachining for a MEMS accelerometer with piezoresistive detection as well as the vibration testing of the acce-lerometer structure by using the MSA-500 Micro System Analyzer, a measurement instrument for analysis and visualization of structural vibrations and surface topography in microstructures such as MEMS devices. The technological results, in correlation with the dynamic behavior of the analyzed microstructure, are discussed. These results will be taken into account for design optimization of the device.

Design and Analysis for Motors Control of a 4-DOF Parallel Robot

In this paper, the complex robotic structure of a new 4-DOF parallel robot is designed in a mechatronic concept that integrates mechanical and control aspects. The kinematic and dynamic analysis for the control of motors that act the robot’s arms are presented. Delphi, LabView and SolidWorks softwares are used. The adopted constructive solution of the robot, designed in SolidWorks, has been presented. Then, the transposition of equations which describe the forward and inverse kinematic model of the robot has been performed using the LabView programming environment, a program that allows calling the servomotors’ control board - NI 7344 acquisition board. The angles for the actuated arms of robot have been calculated based on a program developed in the Delphi environment that contains both models - the forward and the inverse one. In order to determine the motor load, a dynamic computation and a simulation have been achieved in ComosMotion from the SolidWorks programming environment. Different results were extracted in the form of diagrams: the torque for the three servomotors acting the arms, the most loaded servomotor – the one that drives arm 1 and the variation of the angular velocity for the arm 1. Finally, the robot prototype has been achieved and interesting conclusions regarding the analyzed robotic structures have been inferred.

Design and programming of a new 4-DOF

The paper presents an original solution of a 4-DOF parallel robot. Aspects of designing of the robot are described, as well as its programming and experimentation in order to manipulate objects of determined dimensions and to overlap them in form of tower. The robot is able to detect new objects in the workspace; object orientation can be achieved regardless of the angle at which the object is. A good timing between the functions of positioning and orientation has been demonstrated.

Design and Testing of an Automatic Dosing System for Ophthalmic Liquids

The paper presents an original solution of automatic dosing system for ophthalmic liquids. The developed eye drop device delivers droplets of less than 10 μl, in the meantime being able to electronically monitor, record and store the daily treatment performed by the patient at home.

Modal Analysis of a MEMS Cantilever

Micro-Electro-Mechanical Systems (MEMS), also known as micromechatronic devices, integrate on the same chip (substrate) both micromechanical structures and microelectronics components. Microcantilevers are miniaturized beams clamped at one end and with the other end suspended freely outwards. They can be used as resonant structures in nano/micro mass detectors, allowing a quantitative assessment of the (substance) mass attached to these devices. An accurate modal analysis makes possible to estimate the sensitivity of the cantilevers or their ability to detect minimum frequencies shifts induced by the substance absorption. In order to obtain a high sensitivity, the structures must present high resonant frequencies (usually bending or torsion), in close correlation with a small equivalent mass. This paper deals with the vibration testing, modeling and simulation of a silicon rectangular microcantilever, micromachined through MEMS technologies. The results of analytical calculations and numerical computation by finite element analysis (FEM) have been compared with those measured through Laser Doppler Vibrometry (LDV) method using MSA-500 system from Polytec.

3D CAD, CAM and Rapid Prototyping Applied for Cam Fabrication

In this paper, a comparison between CNC manufacturing and Rapid Prototyping technology (FDM – Fused Deposition Modeling process), applied for a cam fabrication, is presented. In the products development area, a substantial support is offered by models, as intermediate between product configuration and technology design. The CAD/CAM/CNC technology is a widely used technique for creating prototypes, as well as production parts, using a subtractive type material-removal procedure from a semi-manufactured article. The rapid prototyping (RP) technologies are additive processes, where the part is built up layer by layer until done, directly from the 3D CAD model, within the precision limits of the chosen process. Similarities and differences between these two coexisting computer driven prototyping processes, the subtractive CNC 3 – axes milled part production and the additive RP/ FDM technique, are pointed out for a disk cam manufacturing as sample part.

Electronic Interface for Pneumatic Grippers Using USB Port

The paper deals with an electronic interface built on Arduino electronics. The interface allows controlling several pneumatic grippers using a PC. The grippers are connected to the PC using the mentioned interface which is connected to PC through USB port. The authors are continuing a work developed since 2005 when a LPT electronic interface was developed.

A comparative study of computation models for dynamic behaviour of MEMS structures

A comparative study of computation models for predicting the vibration modes of some MEMS structures of cantilever type — as suspension arms of the inertial mass of a bulk-micromachined silicon accelerometer, reported to the experimentally measured values of resonance (natural) frequencies, is presented in this paper. The most appropriate values of silicon Youngs modulus depending on the crystal orientation of the structure and the type of model, including also the dynamic Youngs modulus determined by the authors, have been inferred.

New experimental setup for studying the influence of surface material and topography on tribological behavior

The paper presents the results of a scientific research using an original experimental setup dedicated for studying the influence of surface material and topography on tribological behavior. The experimental setup is provided with a safety clutch with two steel disks. On the frictional disk, permanently maintained, a ferodo ring is bonded. The other disk, with the material to be tested, was changed each time. Silicon microtextured wafers and chromium (non)textured thin layers deposited on silicon wafers were tested. The size and shape of the depressions were varied and their influence on the friction coefficient was studied. The angular speed of driver and driven shaft was measured with two non contact tachometers.