Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 5 Articles
Tunnel magnetoresistive (TMR) devices have superior performances in weak magnetic field detection. In this study, TMR devices\nwere first employed to form a circular magnetic flux leakage (MFL) sensor for slight wire rope flaw detection. Two versions of this\ntailor-made circular TMR-based sensor array were presented for the inspection of wire ropes with the diameters of 14mm and\n40 mm, respectively. Helmholtz-like coils or a ferrite magnet-based magnetizer was selected to provide the proper magnetic field,\nin order to meet the technical requirements of the TMR devices. The coefficient of variance in the flaw detection performance\nof the sensor array elements was experimentally estimated at 4.05%. Both versions of the MFL sensor array were able to detect\nmultiple single-broken wire flaws in the wire ropes. The accurate axial and circumferential positions of these broken wire flaws\nwere estimated from the MFL scanning image results. In addition, the proposed TMR-based sensor array was applied to detect the\nMFL signal induced by slight surface wear defects. Amutual correlation analysis method was used to distinguish the signals caused\nby the lift-off fluctuation from the MFL scanning image results. The MFL sensor arrays presented in this study provide inspiration\nfor the designing of tailor-made TMR-based circular sensor arrays for cylindrical ferromagnetic structural inspecti...
This paper proposes an innovative mechatronic piezo-actuated module to control vibrations\nin modern machine tools. Vibrations represent one of the main issues that seriously compromise\nthe quality of the workpiece. The active vibration control (AVC) device is composed of a host part\nintegrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment\nand adjust to alterations in the environment. In particular, an innovative smart actuator has been\ndesigned and developed to satisfy machining requirements during active vibration control. This study\npresents the mechatronic model based on the kinematic and dynamic analysis of the AVC device.\nTo ensure a real time performance, a H2-LQG controller has been developed and validated by\nsimulations involving a machine tool, PZT actuator and controller models. The Hardware in the\nLoop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests\nhas been performed to validate the AVC module on a commercial machine tool. The feasibility of the\nreal time vibration damping is demonstrated and the simulation accuracy is evaluated....
A low-cost method, which integrates distance sensing functionality into a switched\nelectromagnet by using a hybrid switching mode and current ripple measurements, is proposed.\nThe electromagnet is controlled by a micro-controller via a MOSFET H bridge, utilizing\na comparator-based current control. Additionally, a method for calculating the inductance of the\nelectromagnet and approximating the magnetic contact between the electromagnet and its target is\nalso presented. The resulting tool is attached to an industrial robot, and the system performance\nusing this setup is evaluated. Distance sensing in the range of 0mmto 5.2mm is demonstrated. It is\nalso shown that the relation between magnetic contact, coil current and calculated inductance can be\nreduced to a predictive look-up table, enabling the quality of the magnetic contact to be estimated\nusing minimal computational effort....
High integration of multi-functional instruments raises a critical issue in temperature\ncontrol that is challenging due to its spatialââ?¬â??temporal complexity. This paper presents a multi-input\nmulti-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating\nthe temperature environment within a multi-module instrument. The smart system ensures that the\ninternal temperature of the instrument converges to a target without the need of a system model, thus\nmaking the control robust. The system consists of a fully-connected proportionalââ?¬â??integralââ?¬â??derivative\n(PID) neural network (FCPIDNN) and an on-line self-tuning module. The experimental results show\nthat the presented system can effectively control the internal temperature under various mission\nscenarios, in particular, it is able to self-reconfigure upon actuator failure. The system provides a\nnew scheme for a complex and time-variant MIMO control system which can be widely applied for\nthe distributed measurement and control of the environment in instruments, integration electronics,\nand house constructions....
In this paper, the structural behavior of a micro-electromechanical system (MEMS)\ncomposed of two electrically coupled parallel clamped-clamped microbeams is investigated. An Euler\nBernoulli beam model is considered along with the nonlinear electric actuating force to get the\nequation of motion governing the structural behavior of the actuator. A reduced-order modeling\n(ROM) based on the Galerkin expansion technique, while assuming linear undamped mode shapes\nof a straight fixed-fixed beam as the basis functions, is assumed as a discretization technique of the\nequations of motion in this investigation. The results showed that the double-microbeam MEMS\nactuator configuration requires a lower actuation voltage and a lower switching time as compared to\nthe single microbeam actuator. Then, the effects of both microbeams air gap depths were investigated.\nFinally, the eigenvalue problem was investigated to get the variation of the fundamental natural\nfrequencies of the coupled parallel microbeams with the applied actuating DC load....
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