Vahé Nerguizian

A Novel Approach for Mobile Robot Navigation with Dynamic Obstacles Avoidance

This paper proposes a new approach for trajectory optimization of a mobile robot in a general dynamic environment. The new method combines the static and dynamic modes of trajectory planning to provide an algorithm that gives fast and optimal solutions for static environments, and generates a new path when an unexpected situation occurs. The particularity of the method is in the representation of the static environment in a judicious way facilitating the path planning and reducing the processing time. Moreover, when an unexpected obstacle blocks the robot trajectory, the method uses the robot sensors to detect the obstacle, finds a best way to circumvent it and then resumes its path toward the desired destination. Experimental results showed the effectiveness of the proposed approach.

Modeling and adaptive control of redundant robots

This paper presents an adaptive control scheme for a hyper-redundant robot articulated nimble adaptable trunk (ANAT) subject to spatial constraints. An optimization scheme is applied to avoid obstacles in 3D space present in the robots trajectory by using redundancy, and to prevent the robot from retracting and crashing into the base by setting a security envelop. The generation of the trajectory with obstacles avoidance is performed by calculating the differential inverse kinematics of the robot based on the generalized inverse function. The obstacles are modeled by hyper-surfaces in order to reduce calculations and improve the computation time. When the optimal trajectory is attained in presence of the imposed constraints, an adaptive control law is applied to the robot. Simulation results showed the effectiveness of the proposed approach.

Analytical solutions and validation of electric field and dielectrophoretic force in a bio-microfluidic channel

In a microbiological device, cell or particle manipulation and characterization require the use of electric field on different electrodes in several configurations and shapes. To efficiently design microelectrodes within a microfluidic channel for dielectrophoresis focusing, manipulation and characterization of cells, the designer will seek the exact distribution of the electric potential, electric field and hence dielectrophoresis force exerted on the cell within the microdevice. In this paper we describe the approach attaining the analytical solution of the dielectrophoretic force expression within a microchannel with parallel facing same size electrodes present on the two faces of channel substrates, with opposite voltages on the pair electrodes. Simple Fourier series mathematical expressions are derived for electric potential, electric field and dielectric force between two distant finite‐size electrodes. Excellent agreement is found by comparing the analytical results calculated using MATLAB™ with numerical ones obtained by Comsol. This analytical result can help the designer to perform simple design parametric analysis. Bio‐microdevices are also designed and fabricated to illustrate the theoretical solution results with the experimental data. Experiments with red blood cells show the dielectrophoretic force contour plots of the analytical data matched to the experimental results.

Indoor Fingerprinting Geolocation using Wavelet-Based Features Extracted from the Channel Impulse Response in Conjunction with an Artificial Neural Network

This paper proposes a method to localize a mobile station in an indoor environment using wavelet- based features (WBF) extracted from the channel impulse response (CIR) in conjunction with an artificial neural network (ANN). The proposed localization system makes use of the fingerprinting technique and employs CIR information as the signature and an artificial neural network as the pattern matching algorithm. For the considered indoor environment, the obtained CIR information can not be applied directly to the input of the ANN due to the high number of the CIR samples since an ANN with a high number of inputs requires a high number of learning patterns during its training. Consequently, relevant features reflecting the CIR signature have to be extracted and then applied to the ANN. The relevant features may be some physical channel parameters or a compressed version of the CIR signature. In this paper, the extraction of the CIR features is done using a wavelet-based compression. The particularity of the method is in the representation of the CIR signature in a judicious way facilitating the design of the ANN. Moreover, when the extracted features correspond to the CIR signature, the localization system tends to give mobile location with a high precision. Simulation of measured CIR in an indoor environment, showed a precision of 2 meters for 91% and 70% of trained and untrained data, respectively.

Virtual and remote laboratories

The purpose of this paper is to demonstrate virtual and remote laboratories application models for undergraduate engineering students. Two virtual and remote applications are presented. The first application uses a laboratory session on modelling and simulation of level control. The second application shows a real time experiment on level control of a tank system

3D Inclinometer and MEMS Acceleration Sensors

Currently different systems are used to estimate simultaneously linear and angular positions of a mobile frame. This paper presents a novel approach to deduce simultaneously the aforementioned functionalities with only one sensor module. The use of only four MEMS accelerometers represents the main advantage of the proposed system. These accelerometers are mechanically mounted to form an orthogonal frame. The angular positions are determined from earths gravity orientation in the mobile frame. The inclinometer module does not measure horizontal plane rotations, for this reason, plane angular speeds are estimated from the amplitude of the normal acceleration resulting from this type of rotation. Moreover, an angular encoder and a gyroscope are attached at the bottom of the module in order to compare and validate the estimated angular speed in plane rotations. Although this solution can be less precise, it can be an alternative to the expensive products found on the market

A compact size reconfigurable 1-3 GHz impedance tuner suitable for RF MEMS applications

This paper proposes a novel spiral topology for a reconfigurable stub tuner with radio-frequency micro electro mechanical system (RF MEMS) switches. The flexibility of the configuration permits the transformation from single to double and triple stub tuning covering a wide range of impedance values. Moreover, the number of switches present in the tuner dictates the range of loads to be matched. The design produces 2048 different impedances. The design of a spirally rolled parallel coplanar waveguide (CPW) transmission line tuner is presented along with simulation results. The proposed tuner provides real-time reconfiguration and matching for RF loads that could change during system operation. Real time intelligent algorithm would be used to control electronically the tuner. This proposed design would be used for military and high performance circuit applications for future low-cost and low-power intelligent RF micro systems and systems-on-chip.

Holes Effects on RF MEMS Parallel Membranes Capacitors

Parallel membrane RF MEMS capacitors are designed with small diameter holes in the top plate of capacitance due to fabrication process requirements for sacrificial layer removal and modification of dynamic behaviour of the structure. The impact of hole characteristics (size, pitch and ligament efficiency) on the component performance is not very well documented in current literature. Only rules of thumb are used in the design without giving much justification. This study explores and assesses the effect of larger holes with different pitches and ligament efficiencies in fixed top membrane by means of simulations with CoventorWare analyzer simulation software and practical probing tests conducted on specifically designed set of RF MEMS capacitors. The approach used in this study is by varying the RF capacitance with two different axis of comparison. The first being a set of MEMS capacitors having different sized holes of equal combined surface and the second having fixed number of holes with different diameters. The experimental results converge quite adequately with the designed and simulated results giving a clear performance trend and appropriate designer solution. The outcome of this paper improves the degree of freedom of the designer with respect to the manufacturing difficulties for sacrificial layer removal associated to better dynamics and RF performances of the components

Dynamic pressure as a measure of gas turbine engine (GTE) performance

Utilizing in situ dynamic pressure measurement is a promising novel approach with applications for both control and condition monitoring of gas turbine-based propulsion systems. The dynamic pressure created by rotating components within the engine presents a unique opportunity for controlling the operation of the engine and for evaluating the condition of a specific component through interpretation of the dynamic pressure signal. Preliminary bench-top experiments are conducted with dc axial fans for measuring fan RPM, blade condition, surge and dynamic temperature variation. Also, a method, based on standing wave physics, is presented for measuring the dynamic temperature simultaneously with the dynamic pressure. These tests are implemented in order to demonstrate the versatility of dynamic pressure-based diagnostics for monitoring several different parameters, and two physical quantities, dynamic pressure and dynamic temperature, with a single sensor. In this work, the development of a dynamic pressure sensor based on micro-electro-mechanical system technology for in situ gas turbine engine condition monitoring is presented. The dynamic pressure sensor performance is evaluated on two different gas turbine engines, one having a fan and the other without.

Impact of single-walled carbon nanotubes on the embryo: a brief review

Carbon nanotubes (CNTs) are considered one of the most interesting materials in the 21st century due to their unique physiochemical characteristics and applicability to various industrial products and medical applications. However, in the last few years, questions have been raised regarding the potential toxicity of CNTs to humans and the environment; it is believed that the physiochemical characteristics of these materials are key determinants of CNT interaction with living cells and hence determine their toxicity in humans and other organisms as well as their embryos. Thus, several recent studies, including ours, pointed out that CNTs have cytotoxic effects on human and animal cells, which occur via the alteration of key regulator genes of cell proliferation, apoptosis, survival, cell–cell adhesion, and angiogenesis. Meanwhile, few investigations revealed that CNTs could also be harmful to the normal development of the embryo. In this review, we will discuss the toxic role of single-walled CNTs in the embryo, which was recently explored by several groups including ours.