Rocco Rizzo

A discrete-time localization method for capsule endoscopy based on on-board magnetic sensing

Recent achievements in active capsule endoscopy have allowed controlled inspection of the bowel by magnetic guidance. Capsule localization represents an important enabling technology for such kinds of platforms. In this paper, the authors present a localization method, applied as first step in time-discrete capsule position detection, that is useful for establishing a magnetic link at the beginning of an endoscopic procedure or for re-linking the capsule in the case of loss due to locomotion. The novelty of this approach consists in using magnetic sensors on board the capsule whose output is combined with pre-calculated magnetic field analytical model solutions. A magnetic field triangulation algorithm is used for obtaining the position of the capsule inside the gastrointestinal tract. Experimental validation has demonstrated that the proposed procedure is stable, accurate and has a wide localization range in a volume of about 18 × 103 cm3. Position errors of 14 mm along the X direction, 11 mm along the Y direction and 19 mm along the Z direction were obtained in less than 27 s of elaboration time. The proposed approach, being compatible with magnetic fields used for locomotion, can be easily extended to other platforms for active capsule endoscopy.

Analysis and design of an electromagnetic system for the characterization of magneto-rheological fluids for haptic interfaces

In this paper, the synthesis and design of a new device for the energization and characterization of magneto-rheological fluids (MRF) for haptic interfaces are presented. Due to the core structure and feeding conditions, only a three-dimensional numerical analysis provides an accurate prediction of the electromagnetic quantities and the rheological behavior of an excited specimen. The design constraints are shown in details and the results in terms of magnetic field inside the fluid and its spatial resolution are discussed.

Analysis of the performance of a multi-stage pulsed linear induction launcher

In this paper the performance of a multistage pulsed linear induction launcher (PLIL) is analyzed. Attention is focused on the phenomena occurring during the transition between two adjacent stages and on the effects of the coaxial deviation on the motion of the sleeve. The possibility of contacts between the sleeve and the flyway tube and their dynamics is investigated. The analysis has been performed by means of an integral formulation of Maxwell equations that results in an equivalent time varying network. Mechanical coupling has been taken into account assuming a rigid sleeve with three degrees of freedom; the first two are related to the motion of the mass center and the third one is related to rotation around it. Thermal coupling has been considered assuming that the ohmic losses are dissipated adiabatically in the stator windings and in the sleeve. The model has been tested by comparison with results obtained by other researchers in the analysis of a single stage pulsed induction launcher. The analysis of a capacitor-driven five stage launcher has been performed. As the speed of the barrel increases the armature capture effect becomes more evident; the number of contacts with the flyway tube increases and the impacts happen at higher velocity.

The Double-Sided Tubular Linear Induction Motor and Its Possible Use in the Electromagnetic Aircraft Launch System

In this paper, a double-sided stator tubular linear induction machine is presented, and its performance is discussed for possible use as a catapult in the electromagnetic acceleration of aircraft. Based on the use of the Fourier transform in the direction of the motion, a semianalytical model that is able to take into account the end effects due to the finite length of the stators is derived. The effectiveness of the model has been proven by comparison with a numerical analysis based on the finite-element method. The reported results obtained using the two methods show excellent agreement that makes the proposed model a valuable tool for a preliminary design of the device.

A New Passive Maglev System Based on Eddy Current Stabilization

In this paper, a new passive maglev system is presented that is capable to levitate at a short distance from a dedicated guide. The magnetic suspension is assured by the repulsion of proper shaped permanent magnets that are present both on the fixed guide and on the moving suspended part. The presence of a conductive (aluminum) sheet that surrounds the magnets on the guide allows to overcome the intrinsic instability of the system when the suspended part is in relative motion with respect to the guide. The motional induced electric currents on the sheet interact with the magnets of the mover producing a stabilizing force. The detailed structure of the proposed system is described and the main results of the simulations by means of a hybrid electromagnetic FEM-MOM code coupled with the equation of motion of the rigid body are shown and commented.

Electromagnetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids

We report on the design and implementation of innovative haptic interfaces based on magnetorheological fluids (MRFs). We developed 2D and quasi-3D MRF-based devices capable of suitably energizing fluids with a magnetic field in order to build shapes that can be directly felt and explored by hand. We obtained this effect by properly creating a distribution of a magnetic field over time and space inducing the fluid to assume a desired shape and compliance. We implemented different prototypes, synthesized and designed with the help of preliminary simulations by a 3D finite-element code. In this way, both magnetic field and shear stress profiles inside the fluid could be carefully predicted. Finally, we evaluated and experimentally assessed the performance of these devices.

A Wavelet Based Method for the Analysis of Impulsive Noise Due to Switch Commutations in Power Line Communication (PLC) Systems

The aim of this paper is to study the problem of load-time variation in power line communication (PLC) systems and to analyze asynchronous impulsive noise and related channel variations due to switch commutations. A numerical model of the time-varying communication channel is developed by using scattering parameters in the wavelet domain. The proposed method uses the N-port description of the elements that constitute a time-varying PLC system in terms of real matrices with constant elements. This represents a valid alternative to the time domain description usually adopted for analyzing time-varying networks. The comparison with results obtained from other numerical models and with experimental data has confirmed the accuracy and the efficiency of the proposed method.

Analysis of the performance of a combined coil-rail launcher

An electromagnetic system that operates both as a rail and as a coil launcher is proposed, and its performance is analyzed. The device has a composite stator that consists of two rails properly slotted in order to allow the presence of a system of coils. The armature consists of a conductive slab sliding between the rails. Another system of slots is present in the armature where a system of short-circuited coils is placed. A source of constant voltage is connected to the rails and the current flowing in the armature through the sliding contacts produces a thrust force on it. If a proper system of currents able to produce a traveling wave of flux density in the region between the rails is used to feed the barrels, the induced currents that flow in the armatures short-circuited coils produce a further thrust force on the armature itself. The analysis of the behavior of this launcher is performed via a computer code based on an integral formulation and a tool that analyzes the phenomena related to the velocity skin effect; the interactions between the two systems of currents on the armature and the currents on the stator (rails and barrels) are investigated. The thermal behavior of the device has been taken into account by a simple adiabatic model since the short operating time allows one to neglect heat diffusion in the conductive parts of the system. A comparison between the velocities, respectively obtained by separately feeding rails and coils and the system with the combined feeding, has been performed. Preliminary results of the analysis show that this device, because of the presence of two systems of thrust forces acting on the armature, can be successfully used in the acceleration of heavy masses at relatively high velocities, the maximum achievable speed being limited by thermal and mechanical stresses.

TUBULAR LINEAR INDUCTION MACHINE AS A FAST ACTUATOR: ANALYSIS AND DESIGN CRITERIA

In this paper, some design criteria for a Tubular Linear Induction Motor (TLIM) as a fast actuator are considered. The in∞uence of geometrical and physical parameters on the operating conditions of a TLIM are investigated by means a quasi-analytic model. The model is based on the application of the Fourier Transform both in space and in time. The Fourier transform in space is introduced to take into account the flnite length of the stator windings in the axial direction. The transient electrical response of the motor at standstill following the insertion of a three-phase system of voltage generators is performed by the Fourier transform in the time. Linear movements are very usual in mechanical engineering, especially in industrial robots, where linear speeds up to several meters per second are often required. These movements are usually obtained by using rotating motors in combination with rotation to translation mechanism. The resulting systems may have poor performance; in particular, an excessive time delay may prevent their use as fast actuators (1). The complexity of these systems can be overcome by using linear actuators. It is well known that tubular linear induction machines have the highest force to moving mass ratio when compared with other linear motors; this property makes these devices very attractive to be used as servo motors since they may have better performance in terms of reduction of delay times with respect to those of traditional systems. The simplest approach to model these linear motors is based on

Optimal power scheduling in a Virtual Power Plant

This paper proposes a novel approach where the Energy Management System of a Virtual Power Plant decides the optimal power scheduling not on the basis of some predefined policies, but upon the solution of an optimisation problem. The scheduling decision is dynamic as it depends on variable factors, not fully predictable, such as renewable sources availability, electrical energy price, controllable and uncontrollable loads demand and possibility of storing or releasing stored energy. The optimal solution is computed according to a novel cost function that explicitly takes into account only direct costs. Theoretical findings and expectations are proved through simulations of a realistic scenario.