ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: MAGNETOMETERS

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: MAGNETOMETERS Prepared by: Brandon Thurgood Dept. of Electrical and Computer Engineering Utah State University E: bkthurgood@cc.usu.edu ; T: (435)7977577-; F: (435)797-3054 (ECE Dept.) 3/10/2006

2. Outline • Reference List • To Explore Further • Define Attitude Control • Define Magnetometer • Working principles • Major Applications • Types of Magnetometers • Fluxgate Magnetometers • Device Specifications • Magnetometer in space • Ideal magnetometer • Design tradeoffs • Limitations • Calibration • Testing • Honeywell 3-axis magnetometer • Places to buy/Cost ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • http://www.nsti.org/press/PRshow.html?id=633 • http://www.gemsys.ca/index.html • http://www.gemsys.ca/Magnetometers/16_about_magnetometers.htm • http://www.qrg.northwestern.edu/projects/vss/docs/Propulsion/2-what-is-attitude-control.html • http://www.magnetometer.com/products/mags/attcntrl.html • http://scholar.lib.vt.edu/theses/available/etd-07242001-133151/unrestricted/thesis.pdf • http://www.earthsci.unimelb.edu.au/ES304/MODULES/MAG/OBSERVATIONS/obs.html • http://directory.eoportal.org/pres_OERSTED.html • http://www.gfz-potsdam.de/pb1/op/champ/media_CHAMP/champ_front.jpg • http://www.physica.org/xml/article.asp?article=t105a00027.xml • http://www.earthsci.unimelb.edu.au/ES304/MODULES/MAG/NOTES/fluxgate.html • http://www.tuc.nrao.edu/~demerson/magnet/magnet.html • http://www-ssc.igpp.ucla.edu/personnel/russell/ESS265/History.html • http://ist-socrates.berkeley.edu/~jclarke2/SQUID.html • http://hyperphysics.phy-astr.gsu.edu/hbase/solids/squid.html • http://www.izmiran.rssi.ru/magnetism/Petrov/dolgino_rep.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To explore further (web references) • www.goodrich.com • http://www.atomic.princeton.edu/romalis/medical/ • http://www.mphasetech.com/magnetometer.htm • http://www.lund.irf.se/HeliosHome/geomag_magnetometers.html • http://www.sp.ph.ic.ac.uk/~balogh/spinstr.htm • http://server4.oersted.dtu.dk/research/CSC/publica/Papers/Magcalibchamp_PB.PDF • http://www.gmw.com/magnetic_measurements/magmeas.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Attitude Control • Attitude Control determines and monitors the direction a spacecraft. Small mistakes could lead the spacecraft miles off course. Thus, it is important to have accurate sensors and actuators on. Spacecraft attitude systems usually consist of two components: Spacecraft orientation sensors: magnetometers, gyroscopes, etc…; and Control actuators: e.g. reaction wheels, magnetic torque rods, etc… ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Magnetometers The world that we live in is the center of a huge magnet field. A magnetometer isan instrument for measuring the direction and intensity of magnetic fields, including those on or near the Earth and in or around the Human Body. By detecting changes or disturbances in magnetic fields magnetometers are also used to calibrate electromagnets and permanent magnets and to determine the magnetization of materials. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Working Principle of Magnetometers A magnetometer measures the magnetic field in which it resides. The magnetometer outputs three magnitudes in the X, Y and Z directions. This results in the direction and magnitude of the magnetic field B. B= [X, Y, Z]. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Major applications • Retail Security – RFID tag monitoring • Military Surveillance – Perimeter and border control • Pipeline Monitoring – Leaks or rust spots on nuclear pipes • Health Care Monitoring – Monitor the activity of the brain and heart • Compass and GSP application – Direction sensing • Spaceflight – Attitude Control (Will be discussing this application) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Types of Magnetometers • Proton Magnetometers: Usually hydrogen liquid surrounded by coils. A polarizing DC current is passed through the wound coil creating a magnetic flux ,in other words it uses a method of polarization. Applications: inexpensive portable magnetometer, large power consumption and relatively low sensitivity. i.e. engineering surveys, resource exploration, etc… • Overhauser Magnetometers: Using quantum physics as it applies to the hydrogen atom. Occurs when a special liquid (containing free unpaired electrons) is combined with hydrogen atoms. Applications: Greater sensitivity, low power, omni directional, no warm-up time wide temperature ranges, and faster. i.e. vehicle born, volcanology, and marine exploration, long term monitoring, etc… • A SQUID (Superconducting Quantum Interference Device): With the properties of electron-pair wave coherence and Josephson Junctions the SQUID is able to detect very sensitive magnetic fields. Picture is displayed to the right. Applications: highest detection sensitivity, broad temperature ranges, research laboratories.Perform both, DC and AC magnetic moment measurement. i.e. Magnetoencephalogy, Magnetocardiography, Peripheral nerve and Muscle activity, etc… Figure of SQUID magnetometer from hyperphysics ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Types of Magnetometers • Optically Pumped Magnetometers: Using gaseous alkali metals (continuously heated between 45 and 55 degrees Celsius) in a gas cell container, is exposed to light creating light polarization. A small coil applies a RF field to this gas cell. Application: one time adjustment and calibration, superior sensitivity, i.e. vehicle born, volcanology, and marine exploration, etc… • Vector Helium Magnetometer: similar to an optically pumped magnetometers. Helium (He) is contained in the glass cell annd infrared light is transmitted through the cell. Pictures is on the top right. Applications: high power, big mass, high sensitivity, lowe noise. i.e. spaceflight, etc… • Fluxgate Magnetometer: Known as the “magnetic saturation circuit.” Two parallel bars wrapped with a coil are placed close together. As alternating current is passed through the coil causing a magnetic field. Applications, borehole measurements, remanent magnetism, i.e. spaceflight, etc… Figure of a Vector Helium magnetometer from A History of Vector Magnetometry in Space Figure of a fluxgate magnetometer from Geophysical Exploration ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Fluxgate Magnetometer The next few slides look a little more into the fluxgate magnetometer used on most spacecrafts. Figure from A History of Vector Magnetometry in Space Figure from Space and Atmospheric Physics ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Fluxgate 3-axis Magnetometer Figure is a The 3-axis ring-core fluxgate sensor fabricated by UCLA. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Device Specifications Table from Billingsley Magnetics ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Magnetometer in Space • The magnetic field can be measured at a given point in space by a magnetometer. The magnetometer determines the direction and magnitude that the space craft must be moved to obtain the appropriate directions. The magnetometer reads the direction in an x, y, and z coordinates as shown in the bottom figure. With the coordinates that spacecraft can be realigned in the correct direction. Figure of Earth’s magnetic total field intensity from GEMSYS. Figure is from CubeSat at UofI ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. First Magnetometer in Space • Tested and Flown of Sputnik • 1958 the first successful data was collected Figure from Dolginov ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Placement of Magnetometer on Spacecraft Figure from ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Ideal Magnetometer • High sensitivity • Compact • Low power consumption • Low cost • Durable/Ruggedness to shock • Light weight • Insensitive to noise • Large temperature range ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Design Tradeoffs Table thanks to Billingsley Aerospace ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Limitations • Low Sensitivity • High Power Consumption • Size of the magnetometers • Susceptible to other noises such as magnetic disturbances • Availability for space use • Manufacturing costs ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Calibration Spacecraft magnetometers are calibrated once they are in-orbit. The calibration model employed to correct all these errors, are: Bcal t = I +S Bmeas t) +b = A(t)Bmodel (1) where, I = Identity matrix S = Scaling and orthogonality matrix b = Bias (offset) vector A = Attitude rotation matrix Important features of a fluxgate magnetometer and some calibration curves from Magnetic Attitude Determination and Control for Low Earth Orbiting Small Satellites ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Test Measurements Test measurements are on the first FGM-3h fluxgate magnetometer. Vertical axis gives magnetic field. Horizontal is the frequency from the detector. This test was done to check the linearity of the system as different frequencies. Plot of the fluxgate response is from Fluxgate Magnetometer tests: FGM-3h ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Honeywell HMC1041Z Package From ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

23. Places to Buy/Cost • Honeywell • Goodrich • Structure Probe Inc. • LessEMF.com • Cost aprox. $5000.00 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators