1 / 21

Prepared by: Brian Moss Dept. of Mechanical and Aerospace Engineering Utah State University

ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Fluxgate Magnetometer Sensors. Prepared by: Brian Moss Dept. of Mechanical and Aerospace Engineering Utah State University. 3/2/2009. Outline. Reference list To probe further Major applications

gezana
Download Presentation

Prepared by: Brian Moss Dept. of Mechanical and Aerospace Engineering Utah State University

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Fluxgate Magnetometer Sensors Prepared by: Brian Moss Dept. of Mechanical and Aerospace Engineering Utah State University 3/2/2009

  2. Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A typical sample configuration in application • Digital v Analog • Major specifications • Limitations • Other options to consider ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  3. Reference list • www.geo.ucalgary.ca/~wu/Goph547/MagneticMeasurement.pdf • http://www3.imperial.ac.uk/spat/research/areas/space_magnetometer_laboratory • http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6THG-4G4MMHY-1&_user=464852&_rdoc • http://www.igpp.ucla.edu/public/THEMIS/SCI/Pubs/2008_Refereed/auster_fulltext.pdf • http://www.iop.org/EJ/article/0022-3735/12/4/001/jev12i4p241.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  4. Reference List • http://www-ssc.igpp.ucla.edu/st5/design.html • http://en.wikipedia.org/wiki/Magnetometer • http://129.128.241.207/carismaweb/content/view/72/1/ • http://cse.ssl.berkeley.edu/SegwayEd/lessons/exploring_magnetism/background/guide_chapter5.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  5. Major applications • Fluxgate Magnetometers sense the intensity and orientation of magnetic fields • Originally designed to detect submarines in WWII • Now measure fluxuations in earth’s magnetic field due to solar winds and tectonic plate shifts • Many space applications to detect planet’s and moon’s gravitational fields and their orientation • Prospecting for minerals and artifacts underneath earth’s surface • Used extensively in directional drilling ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  6. Basic Working Principles • 2 highly ferromagnetic cores are placed in close proximity to each other symmetrically opposed • Each core is wound with a primary coil, the primary windings are reversed of each other • An alternating current is applied to the primary windings producing a variable mag field in both cores • The induced mag fields in the cores are equal and opposite cancelling each other out when no external mag field is present ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  7. Basic Working Principles ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  8. Basic Working Principles • When an external mag field is present the core generating a field opposite to its direction will come out of saturation sooner while the core in line with its direction will come out of saturation later • During this time the fields do not cancel out and there is a net change in flux • This change in flux induces a voltage across the secondary windings which can be measured ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  9. Basic Working Principles ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  10. Basic Working Principles • It is important that the two cores reach magnetic saturation so that the differences in the fields can be readily known, the greater the susceptibility of the cores the less current needed. • Often to increase sensitivity the core is one ring which can be thought of as two halves still working in opposite directions as the rod cores ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  11. Basic Working Principles ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  12. Typical Fluxgate Magnetometer Configurations ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  13. Typical Fluxgate Magnetometer Configurations • The tuning capacitor is often necessary to ensure that the induced voltage from the sense winding is twice the frequency of the input signal • The synchronous detector compares the phase of the reference block input signal to the received ‘2f’ signal from the sense winding to determine the sign of the measured field • The analog signal is most often converted to digital so that the results can be displayed on an LCD • The sensed voltage is fed back and converted to current that is adequate to cancel out the external field ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  14. Typical Fluxgate Magnetometer Configurations ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  15. Typical Fluxgate Magnetometer Configurations • In digital fluxgate magnetometers the analog signal is converted to digital before integration, phase comparison, and display. It is then converted back to analog through low-pass filters and amplifiers to supply the feedback voltage that is converted to current to cancel out the external field. • To do this digitally the instruments employ Field-programmable gate arrays (FPGA) or Application-specific integrated circuits (ASIC) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  16. Digital v Analog • Digital fluxgate magnetometers are generally lighter, consume less power, show less drift, and better resolution • Digital fluxgate magnetometers however introduce DAC non-linearity into the feedback signal influencing non-linearity into the whole sensor • Analog fluxgate magnetometers generally can operate over a greater bandwidth ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  17. Major Specifications ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  18. Limitations • All fluxgate magnetometers are relative vector instruments that must be calibrated in known magnetic fields and oriented correctly to gain accurate results ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  19. Limitations • Ability to maintain consistent knowledge and stability of sensor axes • The “susceptibility” of the cores to magnetic saturation • Severe temperature changes result in large drifts • All fluxgate magnetometer’s are considered most reliable between 0 to 60 Hz ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  20. Manufacturers and Cost • Applied Physics Systems • ASC Scientific • Bartington Instruments • Billingsley Aerospace • MEDA • THEMIS • Stefan Mayer Instruments • Watson Industries ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  21. Other Options to Consider and Explore • Hall Effect Sensors – often a reliable cheaper substitute in many lab applications • Proton Precession Magnetometer – very accurate sensor that senses the alignment of protons due to a magnetic field, they are less reliant on stable and precise orientation, however they are considerably more expensive ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

More Related