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Cross-section of the sensing element including the permanent magnet acting as sensing core. (1) Magnetostrictive delay line (MDL); (2) pulsed current conductor; (5) soft magnetic material; (6) foam holding the MDL in position without attenuating the propagating elastic pulse; (7) movable permanent magnet; (8) insulating (plastic) film separator.
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In this paper we present a position sensor based on the magnetostrictive delay line (MDL) technique and the eddy currents induced on a soft magnetic material preferably in the form of a ribbon on top of the MDL, which generate elastic micro-strains on the MDL and consequently a pulsed voltage output across a search coil. These eddy currents are due...
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... Fig. 3, the cross-section of the sensing arrangement (A) is illustrated. The MDL (1) is surrounded by low-density foam (6) holding the MDL in position without attenuating the propagating elastic pulse. The foam is set between the two-pulsed current conductors (2) and suppressed by the soft magnetic material (5). Practically this foam may also ...
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Citations
... Other devices based on a delay line principle were suggested in [87,88]. The mechanical strain in the delay line is caused by a current pulse in the perpendicular movable conductor. ...
Magnetic position sensors are popular in industrial and automotive applications since they are robust, resistant to dust and oil and they can be cheap. However, precise magnetic position sensors can achieve 0.015 % accuracy and 10 nm resolution. The maximum achievable range is about 20 m. DC magnetic position sensors are using a permanent magnet as a field source. As a field sensor, magnetoresistors are often used instead of traditional Hall sensors. Eddy current sensors work also with non-magnetic conduction targets. Magnetostrictive sensors are based on the time-of-flight of the elastic wave excited in the magnetostrictive material. The sensors can be several meters long and their applications range from level meters to hydraulics. Magnetic trackers and long-range position sensors utilize AC field sources, which are detectable from distances up to 20 m. Compared to optical instruments magnetic trackers do not need direct view. Their applications include surgery, mixed reality, and underground and underwater navigation.
... Using the magnetostrictive delay line, position can be measured with extreme precision of 10 µm. 9 However, sensors with permanent magnet have two drawbacks. The first drawback is that sensors with permanent magnet use expensive stainless steel piston rod, which is non-magnetic and does not distort the field from the magnet. ...
The position of the piston in pneumatic cylinder with aluminum wall can be measured by external inductance sensor without modifications of the aluminum piston and massive iron piston rod. For frequencies below 20 Hz the inductance is increasing with inserting rod due to the rod permeability. This mode has disadvantage of slow response to piston movement and also high temperature sensitivity. At the frequency of 45 Hz the inductance is position independent, as the permeability effect is compensated by the eddy current effect. At higher frequencies eddy current effects in the rod prevail, the inductance is decreasing with inserting rod. In this mode the sensitivity is smaller but the sensor response is fast and temperature stability is better. We show that FEM simulation of this sensor using measured material properties gives accurate results, which is important for the sensor optimization such as designing the winding geometry for the best linearity.
... This component is placed between the CNC machine stepper motors and the microcontroller, being actually used to amplify the DC current transmitted to the motors from the microcontroller as the control signal as in [13] and [14]. The controller output demands this sort of amplification, depending on the requirements of the motors, so as to convert digital signals into adequate pulses for the operation of the motors, as in [15]. Therefore, in order to drive the stepper motors, the A4988 IC shield was selected, offering the ability of driving a bipolar stepper motor at output current up to 2A per coil. ...
The term Computer Numeric Control (CNC) is referred to an extended variety of electronically controlled machinery being used, among others, in drawing, cutting, milling, extruding and lathing. The fact that accuracy, reproducibility, and automation are achieved through the implementation of computer technology to the control of the machinery, consists an important feature. For the purpose of this project, a conventional three-axis milling machine was actually re-constructed in order to operate under the dictations of a modern microcontroller. The required Graphics User Interface (GUI) was designed from scratch, so as to satisfy the needs of user friendly interaction environment. Moreover, this paper presents a review of such machinery and emphasizes the necessity of attaching modern controllers to them for achieving a “hands-on experience”. This argument is focused on the communication among a personal computer (PC), an “ATMEGA328” microcontroller and the stepper motors which are responsible for the three-dimension movement of the machine. The objective of designing a computer controlled machine emerged from the increasing demands for flexibility and innovation corresponding to edge quality, while in addition the embedded system is designed in terms of achieving cost effectiveness as well as maintaining reliability. This intelligently designed mechanical system along with the embedded one resulting in accuracy, is a C programmable low cost application, based on a microcontroller that has not been previously used for such a purpose.
... The magnetostrictive position sensor is a kind of displacement sensor working in flammable, combustible and poisonous etc. dangerous conditions, and the sensor can be used as liquid level measuring instrument [1,2]. ...
The magnetostrictive position sensor is a kind of displacement sensor utilizing the magnetostrictive effect and inverse effect of magnetostrictive material. The magnetic pole intensity model of elastic wave in the magnetostrictive position sensor was constructed and discussed with the theory of electromagnetism to explain the generating mechanism of elastic wave and to find out the distribution characteristic of impulse source within the magnetostrictive position sensor. Applying the numerical value simulation method, the impulse torsional magnetic field on the sensor line was emulated with electromagnetic theories, and the values of stress distribution were calculated.
... The magnetostrictive position sensor is a kind of displacement sensor working in flammable, combustible and poisonous etc. dangerous conditions, and the sensor can be used as liquid level measuring instrument [1,2]. ...
The magnetostrictive position sensor is a kind of displacement sensor utilizing the magnetostrictive effect and the inverse effect of magnetostrictive material. This essay discussed the generating mechanism of elastic wave within the magnetostrictive position sensor. The magnetic field of magnetostrictive line influenced by the magnetic field of permanent magnet and the impulse current magnetic field were analyzed. The distribution characteristic of the impulse magnetic field and the torsional deflection within the magnetostrictive position sensor were discussed, and appropriate mathematical models were constructed. With the aid of ANSYS, a numerical value simulation software, the impulse torsion magnetic field on the sensor line was emulated with electromagnetic theories. Consequently, this essay should provide the theory basis and data for promoting the signal quality of the signal detection of the sensor. 1548-7741/
... The displacement detection technology realized based on the Magnetostrictive Delay Line (MDL) principle can realize the multi-position and high-precision displacement measurement and is widely applied to the fields of piston position measurement, fluid level measurement, arena, etc [Hristoforou, et al., 2002;Hristoforou, 2006]. Based on the MDL principle, we have developed a new ice thickness monitor apparatus in combination with the environment applicability. ...
Ice thickness is one of the most critical physical indicators in the ice science and engineering. It is therefore very necessary to develop in-situ automatic observation technologies of ice thickness. This paper proposes the principle of three new technologies of in-situ automatic observations of sea ice thickness and provides the findings of laboratory applications. The results show that the in-situ observation accuracy of the monitor apparatus based on the Magnetostrictive Delay Line (MDL) principle can reach ±2 mm, which has solved the "bottleneck" problem of restricting the fine development of a sea ice thermodynamic model, and the resistance accuracy of monitor apparatus with temperature gradient can reach the centimeter level and research the ice and snow substance balance by automatically measuring the glacier surface ice and snow change. The measurement accuracy of the capacitive sensor for ice thickness can also reach ±4 mm and the capacitive sensor is of the potential for automatic monitoring the water level under the ice and the ice formation and development process in water. Such three new technologies can meet different needs of fixed-point ice thickness observation and realize the simultaneous measurement in order to accurately judge the ice thickness.
... Some researchers are based on the capacitive concept for linear displacement sensor567, and some of them use the concept of magnetostrictive linear position sensor [8,9]. Magnetostrictive delay line (MDL) technique and the eddy currents induced on a soft magnetic material also are introduced in [10,11]. In the magnetic based displacement sensor area, many researchers use planar versions with meander coils to detect planar displacements. ...
This paper discusses the effect of inductive coil shape on the sensing performance of a linear displacement sensor. The linear displacement sensor consists of a thin type inductive coil with a thin pattern guide, thus being suitable for tiny space applications. The position can be detected by measuring the inductance of the inductive coil. At each position due to the change in inductive coil area facing the pattern guide the value of inductance is different. Therefore, the objective of this research is to study various inductive coil pattern shapes and to propose the pattern that can achieve good sensing performance. Various shapes of meander, triangular type meander, square and circle shape with different turn number of inductive coils are examined in this study. The inductance is measured with the sensor sensitivity and linearity as a performance evaluation parameter of the sensor. In conclusion, each inductive coil shape has its own advantages and disadvantages. For instance, the circle shape inductive coil produces high sensitivity with a low linearity response. Meanwhile, the square shape inductive coil has a medium sensitivity with higher linearity.
... Various types of position sesnors have been proposed based on the MDL technique, involving measurement of moving permanent magnet [4], conductor [5] and soft magnet [6]. One of the first attempts for sensitive measurement of the displacing permanent magnet has been described in [7], while industrial possible products may be depicted in [8,9]. ...
In this paper a cordless position sensor based on the Magnetostrictive Delay Line
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... Position detection in the micro-scale is typically achieved by employing potentiometers [8], magnetorestrictive effects [9], laser inteferometry [10], optical effects [11] and capacitance sensors [12]. Each method presents certain characteristics regarding the obtained resolution, the applicable range and the overall cost of the measurement setup. ...
A micro system utilizing a novel sensing principle is presented in this paper. The determination of position is performed by exploiting the heat transfer between a heating source and a sensing device. The device itself consists of an array of temperature sensing elements, fabricated entirely on a plastic substrate. A specific fabrication technology was implemented which allows direct integration with read-out electronics and communication to the macro-world without the use of wire bonding. The fabricated sensing elements are temperature sensitive Pt thermistors. The device is able to detect both the position and the motion of a heating source by monitoring the induced resistance variation on the thermistor array. The heating source which performs a one-dimensional motion in a parallel plane to the temperature sensing array can be any element that can provide a highly localized temperature field. The system operation was characterized under both steady-state and dynamic conditions. In steady state mode the sensor exhibits a resolution of ±50 μm, while in dynamic conditions the device can detect signal frequencies up to 10 Hz.
... Current research on magnetostrictive sensors focuses on the use of amorphous magnetostrictive ribbons and fibers as transmitting elements for improved electromechanical coupling [5], as well as the optimization of the process of emission of the ultrasonic signals [6]. ...
Magnetostrictive (MS) sensors are based on the transmission of ultrasonic signals in a waveguide and constitute an interesting alternative to optical encoders for long-range absolute high-precision measurement of linear position. Despite their inherent conceptual simplicity, many aspects of the sensor design must be considered to achieve an accuracy in the 10-mum range. This paper describes research in a new kind of MS linear position sensor, focusing on the enhancement of the processes of generation, transmission, and reception of the ultrasonic waves, with the aim of obtaining high measurement accuracy. Empirical results obtained with a sensor prototype indicate an improvement of six times over the precision of standard MS sensors.
