Constantin Nitu

Optomechatronic system for position detection of a mobile mini-robot

This paper presents an optomechatronic system which can detect, by triangulation, the position of a light point source, fastened onto a robot part. The sensing system consists of two positioning modules for optical transducers, which automatically follow the direction of the light point source. The system control is accomplished by means of data acquisition boards and LabVIEW programming.

Investigation of the rotating arc plasma generated in a vacuum circuit breaker

The main goal of this work is a better understanding of the physical phenomena taking place during the high currents interruption process, corresponding to short-circuit regime in the electrical networks. The arc appearance and its behavior in vacuum circuit breakers with cup-shaped electrodes were explored with an adequate optical system. Different current interruption situations were correlated with optical plasma diagnosis. Specific peculiarities of the time resolved spectra recorded in the proximity of the short circuit current zero (c.z.) moments are reported. On this basis the authors attempt to define a set of plasma parameters which are critical for the studied interruption processes and the breaking capability evaluation.

Ankle-Knee Rehabilitation System

In this paper is present a new type of a rehabilitation system for both knee and ankle that integrate two treatment types. The system allows a continuous passive motion consisting of two rotations of the leg segments, one of the knee articulation and one of the ankle joint, allowing the functional rehabilitation of the individuals that have an impairment of walking due to a disease or an accident. This is one novelty of the system because all the system that are on the market now consider to one articulation that can be knee or the ankle. In addition, the system allows the application of a mechanical vibration at the lower level of the leg, which have a beneficial action on the bones, muscle, and nerves, which is a well-known treatment.

Current State of Anthropometric Parameters Measurement with Relevance for Advanced Lens Optometric Compensation

In recent years, in optometry, more emphasis is laid on the accurate measurements of the individual parameters depending on the main field activity of a patient during a working day. The lens built with individual parameters is a lens that gives the wearer maximum comfort. The devices for measuring these parameters have changed considerably, from an ordinary ruler for measuring the pupillary distance, to the latest generation devices that, by taking pictures, calculate all the needed parameters. The devices for parameters measuring are mobile or stationary units and include complex software that converts pixels that make up the picture took to the patient in distances. Hence, measurements can be entered into the software generator Free-Form of lens processing to customize them. The article presents the common problems in measurement of anthropometric parameters necessary for an advanced optometric compensation. The measurement methods, from very simple and cheap to actual image-processing based method, are presented with an emphasis on disadvantages and advantages of each one. Future direction of improvement is included.

Reflected hotspot used in industrial vision

The paper deals with the measuring of a robot displacement, by stereo image matching; images of a hotspot placed onto the robot, generated by LASER reflected radiation are acquired by two CCD cameras; the reflective point is up to designer, in this particular case being the reflective surface of a small ball placed in view field of cameras. The technique to determine the 3D displacement of the robot, using the image matching approach, is presented. Using a pair of stereo images, the coordinates for a set of points belonging to the robot in a reference position are computed in a 3D Cartesian system. The procedure is then repeated for a new position. In order to demonstrate the validity of this technique, some experimental results are also presented.

Upon the Interaction between Magnetic Field and Electric Arc in Low Voltage Vacuum Circuit Breakers

The paper presents an investigation of the magnetic field influence within low voltage switching process in vacuum, in the case of strong currents interrupting. The axial, transverse and radial magnetic field action upon the vacuum electric arc behavior is analyzed on a mono-phase model. The conclusions obtained by modeling the electromagnetic field in the vacuum quenching chamber are compared with the experimental results. The experimental set-up can reproduce the real switching conditions of the power vacuum circuit-breaker. The goal of the study is the improvement of the circuit-breaker switching capabilities.

Three DOF actuator for optical parts micropositioning

The actual growth of high-technologies and future applications in micro- and nano-manufacturing have raised the need for low cost / high performance micro-positioners. Photonic packaging, optical device testing, MEMS positioning/alignment, fiber alignment, micromachining, micro-manipulation, semiconductor handling systems, microsurgery are some examples of applications, from which the most are in the optical field. Very often, micro-positioning systems with micron or submicron resolution m needed to be run open loop, without feedback position sensors. Such devices are achievable with strain actuators like piezoelectric, magnetostrictive or electrostrictive ones. Two kinds of actuators could be used, with continuous motion or with discrete motion. The first could reach all the points from a space but request real time control. The second could reach only a finite number of points in space, but the command is binary, easy to implement. The working space for discrete actuators can be reached using a lot of actuators, series connected. The paper presents a piezoelectric actuator with 3 DOF, that could be used for micro-positioning. The investigated actuator is a scale model, for checking the principle and the models.

Micropositioning devices for optical applications

Many industrial applications (optical devices, micro/nanotechnology, etc.) require the development of advanced positioning systems. They should have submicronic resolution, often in a practically unlimited working range, as well to be stable, reliable and to have compact construction. By use of piezoelectric materials, devices having the potential to control the system structure and consequently the degrees of freedom of the mechanical components could be achieved. The paper presents some of the actuators, built and experimentally tested by the authors, as well as their associated mathematical models.