Spatial angular positioning device with three-dimensional magnetoelectric sensors D T Huong Giang, P A Duc, N T Ngoc, N T Hien, and N H Duc Citation: Review of Scientific Instruments 83, 095006 (2012); doi: 10.1063/1.4752763 View online: http://dx.doi.org/10.1063/1.4752763 View Table of Contents: http://scitation.aip.org/content/aip/journal/rsi/83/9?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Piezoelectric-metal-magnet dc magnetoelectric sensor with high dynamic response J Appl Phys 114, 027016 (2013); 10.1063/1.4812225 A pencil-like magnetoelectric sensor exhibiting ultrahigh coupling properties J Appl Phys 113, 134101 (2013); 10.1063/1.4798509 Overlap of the intrinsic and extrinsic magnetoelectric effects in BiFeO3-PbTiO3 compounds: Potentialities for magnetic-sensing applications J Appl Phys 113, 034102 (2013); 10.1063/1.4775796 Comparison of noise floor and sensitivity for different magnetoelectric laminates J Appl Phys 108, 084509 (2010); 10.1063/1.3486483 Geomagnetic sensor based on giant magnetoelectric effect Appl Phys Lett 91, 123513 (2007); 10.1063/1.2789391 This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 REVIEW OF SCIENTIFIC INSTRUMENTS 83, 095006 (2012) Spatial angular positioning device with three-dimensional magnetoelectric sensors D T Huong Giang,a) P A Duc, N T Ngoc, N T Hien, and N H Duc Department of Nano Magnetic Materials and Devices, Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, Vietnam National University, Hanoi E3 Building, 144 Xuan Thuy Road, Cau Giay, Hanoi, Vietnam (Received 21 June 2012; accepted 31 August 2012; published online 20 September 2012) This paper reports on the development of a novel simple three-dimensional geomagnetic device for sensing the spatial azimuth and pitch positions by using three one-dimensional magnetoelectric sensors assembled along three orthogonal axes This sensing device combines piezoelectric transducer plates and elongated high-performance Ni-based Metglas ribbons It allows the simultaneous detection of all three orthogonal components of the terrestrial magnetic field Output signals from the device components are provided in form of sine and/or cosine functions of both the rotation azimuth and the pitch angles, from which the total intensity as well as the inclination angle of the Earth’s magnetic field is determined in an overall field resolution of better than 10−4 Oe and an angle precision of ±0.1◦ , respectively This simple and low-cost geomagnetic-field device is promising for the automatic determination and control of the mobile transceiver antenna’s orientation with respect to the position of the related geostationary satellite © 2012 American Institute of Physics [http://dx.doi.org/10.1063/1.4752763] I INTRODUCTION The intensity as well as the inclination of the terrestrial magnetic field felt by a suspending object is a well known function of the object’s geographic position on the Earth or in the space Geomagnetic-field sensors are, thus, effectively used for the orientation and local positioning of moving objects and in motions generally In this sense, geomagneticfield sensors are indispensable for applications in the space engineering and technology sector, especially in measurements of the magnetic field or of the spatial magnetic-field gradient for different purposes The magnetic field in-orbit can be sensed for geomagnetic-field measurements, or also inversely, for the determination of the relative orientation of, for instance, a spacecraft in the geomagnetic field, i.e., its relative position and orientation with respect to the Earth This is indeed the purpose and function of the magnetic sensors in the attitude control systems (ACS).1 The ACS of a spaceship is devoted to determine and to control the orientation of it, i.e., to sense and to adjust its relative orientation within an inertial reference frame For missions like those of some communications satellites, for example, the relative orientation between the geostationary satellite and the mobile transceivers must be omni-directional controlled For such purposes, angular positioning devices require a very high sensitivity to accurately determine both the spatial azimuth (ϕ) and pitch (θ ) angles with respect to the orientation of the Earth’s magnetic field Various types of magnetic sensors on the basis of fluxgate, Hall effect, superconducting quantum interference, and giant magnetoresistance spin valves have been deployed until now for these applications.1, In addition, many types of 2-D and 3-D magnetic sensors have also been proposed for such applications The proposed devices were manufactured in difa) Electronic mail: giangdth@vnu.edu.vn 0034-6748/2012/83(9)/095006/6/$30.00 ferent technologies based on various physical phenomena as detection principles.3–5 The recently explored magnetoelectric (ME) effect has offered great possibilities to develop a new generation of simple, low-cost but highly sensitive magnetic sensors, which can be used in those devices.2, 6–9 Indeed, we have newly reported an optimal design of a ME-based terrestrial magnetic-field sensing device combining elongated high-performance Ni-based Metglas ribbons and piezoelectric transducer (PZT) plates.6 This 1-D device exhibited a field sensitivity of better than 0.850 V/Oe and a field resolution in the order of 10−4 Oe On the basis of the above mentioned 1-D geomagnetic device, a new ME-based 3-D one has been developed for detecting spatial azimuth and pitch distance in this paper We will show that this 3-D device can simultaneously sense all three orthogonal components of the Earth’s magnetic fields From these data, complete and detailed quantitative information can be obtained on the resulting magnetic field intensity as well as the azimuth and pitch angles at a given device’s position and orientation with respect to the Earth’s magnetic field An overall intensity and angular resolution of better than 10−4 Oe and 10−1◦ , respectively, have been achieved with this device This suggests that the so far developed, simple, lowcost and highly sensitive geomagnetic-field device is promising for potential applications in controlling the relative orientation between mobile transceivers and a geostationary communications satellite II THE CONFIGURATION OF THE 3-D ME SENSOR As shown in Fig 1, the 1-D geomagnetic-field sensors were designed and fabricated in a sandwich configuration of a Metglas/PZT/Metglas ME laminate composite, reported recently in Ref In this configuration, the ME 83, 095006-1 © 2012 American Institute of Physics This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 095006-2 Giang et al Rev Sci Instrum 83, 095006 (2012) FIG One-dimensional ME sensor construction: (a) SEM images at low and high (see the image in the inset) magnification of the sandwiched Metglas/PZT/Metglas 15 × mm2 ME laminate composite with the vectors hac and P indicating the applied ac magnetic field and the electrical polarization direction, respectively The Metglas and the adhesive layer with the respective thickness of 18 μm and μm are recognized (b) The 1-D ME sensor prototype where the coil generating an ac field is directly wrapped around the ME laminates laminates consist of one out-of-plane poled PZT plate sandwiched between two magnetostrictive Metglas laminates (Fig 1(a)) The 500 μm-thick piezoelectric plates used were of the type APCC-855 supplied by The American Piezoceramics Inc., PA The 18 μm-thick magnetostrictive laminates were cut from Fe76.8 Ni1.2 B13.2 Si8.8 melt-spun (also called Ni-based Metglas) ribbons with the size of 15 × mm2 The PZT plate was mechanically firmly sandwiched between the two Metglas layers by using an epoxy layer of around μm-thickness The total laminate volume is of about 15 × × 0.55 mm3 To form the 1-D geomagnetic-field sensor, a solenoid coil with turn density of 10.5 turns/mm was wrapped around the entire sandwiched ME laminates (Fig 1(b)) The 3-D geomagnetic-field sensor was then created by assembling three 1-D sensors S1 , S2 , and S3 aligned along the three orthogonal axes, as shown in Fig 2(a) Figure 2(b) shows the fixed geocentric reference frame (XE , YE, ZE ) for determining the directions and angles, in which the XE -axis is pointing toward the magnetic North pole, the YE axis pointing toward the East pole, and ZE -axis is vertical, positive pointing towards the Earth’s center Here, the azimuth angle is defined as a horizontal angle measured in clockwise rotating from XE axis to the S1 -sensor The pitch angle is then determined by the angle between the S3 -sensor and ZE -axis by clockwise rotation of the 3-D sensor around the XE -axis, i.e., in the verti- FIG Photograph of the simple 3-D rotation system setup cal planes (see Fig 2(c)) This 3-D sensor is then mounted on a simple 3-D rotating system by combining rotations in just horizontal and vertical planes (Fig 3) III ME LAMINATE CHARACTERIZATION A Resonating frequency and quality factor The ME laminate composites were characterized under a weak ac magnetic field hac (hac = ho sin(2π fo t)) in the presence of a bias dc magnetic field H In the our experimental setup, the output voltage induced across the PZT plate by the ac field was measured on a commercial lock-in amplifier FIG The image of 3-D ME sensor prototype (a) and illustrations of the azimuth (b) and pitch (c) angles referred to the fixed axes of the geocentric reference frame (XE ,YE ,ZE ) corresponding to North-East-Down (NED frame) with the Earth This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 095006-3 Giang et al Rev Sci Instrum 83, 095006 (2012) FIG Frequency dependence of the MEVC for ME laminate composites corresponding to sensors S1 , S2 , and S3 The inset shows the signals in details around the resonating frequencies (Model 7265, Signal Recovery), which simultaneously supplied the input current for hac An electromagnet was used to provide the bias field while the oscillating field with amplitudes of hac = 10−2 Oe was generated by a Helmholtz coil The magnetoelectric voltage coefficient (MEVC-α E ) was then determined from the magnetoelectric voltage response (MEVR) VME versus the applied magnetic field by the equation αE = VME hac · tPZT (1) with tPZT as the PZT plate thickness For illustration, Fig shows the frequency dependence of the MEVC for investigated ME composite laminates at a fixed bias dc magnetic field of Oe Note that the wellpronounced peaks of resonance are clearly observed and their height is enhanced with the increasing bias dc magnetic fields up to a certain value (see Fig below) These peaks are found to locate at the resonating frequencies fr of 99.95, 100.18, and 100.13 kHz for the S1 , S2 , and S3 sensors, respectively, with a quality factor of around 1.5% The difference between the observed resonating frequencies, however, is of less than 0.5%, i.e., still within the bandwidth range of the resonating frequency In the present work, the slight difference in the resonating frequencies of the S1 , S2 , and S3 sensors may relate to mechanical coupling modifications which could be caused in the different manually manipulated lamination processes FIG Bias magnetic-field dependence of the MEVC at the resonating frequencies of the ME laminate composites for the corresponding sensors S1 , S2 , and S3 IV GEOMAGNETIC SENSOR CHARACTERIZATIONS A Sensor calibration In the working mode of the ME geomagnetic-field sensor, the solenoid coils in all of the 1D-ME sensors always function as ac magnetic-field generators at their individual resonating frequencies and they all are fed by an ac current source On the other hand, in this measuring arrangement, the terrestrial magnetic field, which should be sensed and determined, plays the role of the dc magnetic field H For an operation test of the as-fabricated sensor in the conventional intensity range of the geomagnetic field, however, a commercial Helmholtz coil supplied by a Keithley 230 current source was used to generate the terrestrial-like magnetic field of the intensity in the range up to 1.5 Oe with the accuracy of 10−5 Oe In this mode, the observed MEVR from the S1 , S2 , and S3 sensors in the presence of the low external magnetic fields are shown in Fig The figures obviously indicate a linear variation of ME-voltage with the external magnetic field in the field range of interest From this result, it turns out that the magnetic field calibration coefficient k of the sensors could be derived as k1 = 192.6, k2 = 200.8, and k3 = 205.5 mV/Oe corresponding to the field resolution of × 10−4 Oe for the S1 , B Magnetic-field intensity dependence of the MEVC The MEVC at the individual resonating frequencies are presented in Fig in the dependence on the bias dc magnetic field for all investigated ME laminate composites As can be seen, despite a few slight discrepancy related to various detailed aspects of the sensor’s technical (geometrical, fabrication) parameters, the MEVC data for all measured ME laminate composites show a significantly similar behavior in the curves as well as in the absolute magnitudes The MEVC initially increases with the applied magnetic field and reaches a maximum value as high as 130 V/cm Oe at the applied field intensity of around Oe and then decreases as the applied magnetic field further increases FIG MEVR at low external magnetic fields for the corresponding sensors S1 , S2 , and S3 The included fitting curves indicate the field sensitivity (and/or field calibration coefficients) This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 095006-4 Giang et al Rev Sci Instrum 83, 095006 (2012) FIG MEVR data versus azimuth ϕ-angle excited by two ac magnetic fields with an 180◦ phase shift difference (hac and –hac ) described in the Cartesian (a) and polar coordinate (b) S2 , and S3 sensors, respectively These calibration coefficients (and/or sensor sensitivities) reveal an amplitude discrepancy of about 5% They are, however, two orders of magnitude better than those previously reported for similar magnetic-field sensor devices, but comparable with that of available commercial geomagnetic-field sensors.10, 11 This also reveals the excellent capability and suitability of our as-developed and as-described sensor for an accurate determination of the geomagnetic field B Offsets calibration Presented in Fig 7(a) is the S1 -sensor output MEVR versus azimuth ϕ-angle measured by rotating the sensor system in the horizontal plane about ZE -axis It is clearly seen that the recorded sensor signal well corresponds to the harmonic cosine function of the rotation angle ϕ The signal, however, is accompanied by a rather high non-zero offset value This offset shift can be manually evaluated from zero to the center value between the maximum and minimum peaks In our sensor, this problem was automatically solved by averaging the two output signals excited by the two ac magnetic fields of a 180◦ phase shift difference (denotes as hac and –hac ) The non-zero offset contribution to the MEVR is represented by the cardioids in the polar coordinate in Fig 7(b) The offset shall centralize the circle by averaging where the circle radius indicates the amplitude of the offset signal C Terrestrial magnetic-field intensity and spatial azimuth angle positioning The amount of azimuth rotation of the sensor S1 with respect to the North magnetic pole (XE -axis) is sensed by turning the 3-D sensor system about the ZE -axis Here, the sensors S1 and S2 are in the Earth surface’s (horizontal) plane The offset-compensated signals from the S1 , S2 , and S3 sensor versus the ϕ-angle in a complete circular cycle are plotted in Fig 8(a) The two V1 and V2 curves correspond well to the cosine and sine functions of the rotation angles ϕ These signals always reach a maximum of 77 and 80.3 mV in the S1 and S2 sensors, respectively, when the sensors are pointing to the North direction When the sensor was oriented along the East and/or West direction in this plane, its output diminished to zero As seen in the figure, the V3 curve of the respective S3 -sensor is an almost perfectly flat line around 40.9 mV The positive sign means that the magnetic field of the Earth is pointing down at our location (located in the Northern hemisphere) By using the magnetic-field calibration coefficients of the respective sensors as mentioned above, three components (H1 , FIG (a) MEVR from the S1 , S2 , and S3 as a function of the azimuth angle plotted in the Cartesian coordinate, (b) the three derived orthogonal Hi (= Vi /ki ), horizontal component (Hxy ) components and the total intensity (Htot ) of the Earth’s magnetic field described in the polar coordinate and (c) the angles in degree unit calculated from the arctangent function of ratio (H2 /H1 ) and (H3 /Hxy ) corresponding to azimuth and inclination angle of the Earth’s field This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 095006-5 Giang et al Rev Sci Instrum 83, 095006 (2012) FIG (a) MEVR from the S1 , S2 , and S3 as a function of the pitch angle plotted in the Cartesian coordinate, (b) the three derived orthogonal Hi (= Vi /ki ), vertical (Hz ) components and the total intensity (Htot ) of the Earth’s magnetic field described in the polar coordinate and (c) the pitch angles in degree unit calculated from the arctangent function of ratio (H2 /H3 ) H2 , H3 ) of the Earth’s magnetic field were derived and they are plotted in the polar coordinate system (see Fig 8(b)) In this description, the data are distributed on almost perfect circles From these orthogonal components, the horizontal (Hxy ) and the total (Htot ) terrestrial magnetic-field intensity can be computed using the expression Hxy = H12 + H22 , Htot = H12 + H22 + H32 (2) The plots of Hxy and Htot in the polar coordinate system are also shown in Fig 8(b) It turns out in this experiment that the strength of the horizontal terrestrial magnetic field Hxy in our localized laboratory conditions (Hanoi, Vietnam) is in the order of 0.3998 Oe and the strength of the total Earth’s magnetic field Htot equals to 0.4466 Oe Combining the derived terrestrial magnetic-field horizontal (Hxy ) and the vertical components (H3 ), the inclination (or dip) angle of the Earth’s field to the surface of the Earth can be directly determined by using the arctangent function of (H3 /Hxy ) The calculated results presented in Fig 8(c) are almost invariant at around θ i = 26.5 ± 0.1◦ An acceptable discrepancy of 0.1◦ is appropriate with an extremely small change in the magnetic field strength estimated 10−4 Oe that can be reliably resolved by this sensor Although the measurements were performed under best arranged experimental conditions for the purpose of studying the geomagnetic field, the results may still be influenced by indoor objects This finding, however, is in good consistency with standardized data reported previously.12–14 For the determination of the azimuth ϕ-angle, only the two sensors S1 and S2 of the respective H1 and H2 components are involved by using the relationship tanϕ = tan(H2 /H1 ) To account for the tangent function being valid over 180◦ and not allowing the H1 division calculation, the following equations can be used: H1 H1 H1 H1 H1 = and H2 < : ϕ = 90o , = and H2 > : ϕ = 270o , > and H2 < : ϕ = − arctan (H2 / H1 ) , < : ϕ = π − arctan (H2 / H1 ) , > and H2 > : ϕ = 2π − arctan (H2 / H1 ) (3) The derived results converted to degrees as presented in Fig 8(c) show a perfect linear variation with the experimental ϕ-angle of a slope exactly equal to D Spatial pitch angle positioning The sensor signals depending on the pitch angle (θ ) between the S3 -sensor and the reference ZE -axis were measured Figure 9(a) illustrates the S2 and S3 sensor readings when turning the 3-D sensor around the S1 -sensor axis, i.e., around the North direction This plot again shows a sine and cosine output response to the θ -angles during the rotation for the two respective sensors S2 and S3 In this case, the V1 curve of the corresponding S1 sensor is again an almost perfectly flat line around 77 mV The maximum values of 40 and 40.9 mV for the sensors S2 and S3 , respectively, always were reached when the sensor axes are pointed vertically downward (i.e., along the ZE axis) The plots of the derived components (H1 , H2 , H3 ) of the Earth’s field in the polar coordinate system (shown in Fig 9(b)), again, are well fitted in perfect circles By using the relationship tanθ = tan(H2 /H3 ) and the same equation (1) applied for the ratio of (–H2 /H3 ), the pitch angle θ was again determined Results presented in Fig 9(c) give exactly the experimental pitch angle in complete circular rotation cycle V CONCLUSIONS A novel 3-D geomagnetic device for detecting the azimuth and pitch positions has been developed on the basis of three simple, low-cost and high-sensitivity 1-D ME sensors arranged in a perpendicular configuration The device allows simultaneous detections of all the three orthogonal components of the terrestrial magnetic field Its output signals in form of sine and cosine function of the rotation azimuth and pitch angles provide complete and detailed quantitative information on the intensity of the terrestrial magnetic field as well as the value of the azimuth and pitch angles with respect to the direction of the Earth’s magnetic field The overall intensity and angular angle accuracy of the device has been determined as better than 10−4 Oe and 10−1◦ , respectively This sensor is This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 095006-6 Giang et al being integrated with an electronic interface on a mobile satellite signal receiver for the automatic determination and control of the latter antenna direction with respect to the satellite position in space ACKNOWLEDGMENTS This work was supported by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under the granted Research Project No 103.02.86.09 and by the National 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Geomagnetism and Magnetic Prospecting (Vietnam National University, 2005) 13 See http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcIGRFWMM for information about the inclination angle and the total terrestrial magneticfield intensity located at Hanoi, Vietnam 14 See http://magnetic-declination.com/ for information about the inclination angle and the total terrestrial magnetic-field intensity located at Hanoi, Vietnam L This article is copyrighted as indicated in the article Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions Downloaded to IP: 128.240.225.44 On: Sat, 20 Dec 2014 01:20:34 ... (2012) Spatial angular positioning device with three-dimensional magnetoelectric sensors D T Huong Giang,a) P A Duc, N T Ngoc, N T Hien, and N H Duc Department of Nano Magnetic Materials and Devices,... geomagnetic-field device is promising for the automatic determination and control of the mobile transceiver antenna’s orientation with respect to the position of the related geostationary satellite ©... communications satellites, for example, the relative orientation between the geostationary satellite and the mobile transceivers must be omni-directional controlled For such purposes, angular positioning