TechnicalLecturePresentationAccelerometers.ppt
- 2. Introduction Master of Ceremonies Ryan Popa Accelerometers Background and Applications Jeremy Iamurri Technical Explanation and Physics Yan Sidronio Magnetometers Background and Applications Austin Fletcher Technical Explanation Chris Sigler Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 3. Accelerometers - History - Types Accelerometers behave as a damped mass on a spring. Acceleration causes displacement of this "spring" proportional to the acceleration experienced. • Original Invention o 1923 - Burton McCollum and Peter Orville o Commercialized in 1927 • Piezoelectric o 1943 - Used Rochelle salt • Piezoresistive o 1959 - Warren P. Mason Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions Original Accelerometer Patent Piezo-based Accelertometers
- 4. • Hall Effect o 1961 - Heinz E. Kallmann • Magnetoresistive o 1973 - Tetsuji Shimizu • Capacitive o 1989 - Hitachi, Ltd. • Digital Capacitive o 1994 - William C. Tang/Ford Motors Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions Accelerometers - History - Types Hall Effect Accelerometer
- 5. Accelerometer - Applications • Video games • Hard drive protection • Electronic Stability Package • Vehicle crash detection Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 6. Acceleration: . At sea level we experience 32.2 ft/s2 = 9.81 m/s2 = 1g Examples of g-forces: This room = your weight = 1g Bugatti Veyron, 0 to 60mph in 2.4s= 1.55g Space Shuttle reentry & launch = 3g Top Thrill Dragster roller-coaster = 4.5g F-1 car cornering = 5g to 6g Max for fighter jet pilots = 11g to 12g Max experienced by a human* = 46.2g Death or extensive & severe injuries= +50g Modern accelerometers are small microelectromechanical systems (MEMS) consisting of a cantilever beam with a proof Accelerometer - Fundamentals * John Stapp on December 10th, 1954 in the rocket sled "Sonic Wind" going over 632 MPH and stopping over a water break. Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 7. Capacitive Accelerometer Cantilever made of silicon, holding two plates suspended between energized reference rails. Our knowledge of the elasticity of silica is the basis of acceleration sensing. Structure is symmetric, reducing temperature effects and providing more precise measurement. As the reference "mass" approaches one reference plate, the air-gap to the other reference plate increases. Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions The device operates with a DC input voltage. VOUT-DC will change linearly to acceleration variations. Vout = Vg0 + Vsens.*G ; VSensitivity=(Vout,+1g - Vout-1g)/(2g) This design is cheap and usually accurate to +/- 0.01g, have a shock tolerance up to 200 Km/s2 and sensitive to at least 1.5V/g with a VCC of 5.0V.
- 8. Accelerometer - Examples DE-ACCM6G Buffered ±6g Accelerometer • Dimension Engineering • Has ±6g sense range • 222 mV/g sensitivity Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 9. Accelerometer - Examples Acceleration to voltage example: ”What voltage will correspond to an acceleration of -0.5g?” The 0g point is approximately 1.66V. Sensitivity is 222mV/g Vout = Vg0 + Vsens.*G. -0.5g * 0.222mV/g = -0.111V 1.66V – 0.111V = 1.55V Therefore you can expect a voltage of approximately 1.55V when experiencing an acceleration of -0.5g. Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 10. Accelerometer - Examples Tilt to voltage example: “I am making an antitheft device that will sound an alarm if it is tilted more than 10º with respect to ground in any direction. I have measured the 0g bias point to be 1.663V, and I want to know what voltage to trigger the alarm at.” Sin(10º) = 0.1736 so acceleration with a tilt of 10º will be 0.1736g 0.1736g * 0.222V/g = 0.0385V 1.663 + 0.0385 = 1.7015V 1.663 – 0.0385 = 1.6245V Sound the alarm when the voltage reaches more than 1.7015V or less than 1.6245V. Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 11. Magnetometers - Background • Compass invented by the Chinese in the 4th century • Carl Gauss invents the "magnometer" in 1833 • Two types of magnetometers o Scalar - measures the total strength of the magnetic field they are subject to o Vector - measure the component of the magnetic field in a particular direction, relative to the spatial orientation of the device Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 12. Magnetometer - Applications Geology and planetary science Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 13. Magnetometer - Applications Military applications Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 14. Magnetometer - Applications Archaeology and salvage Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 15. Magnetometer - Applications • Navigation • Compass • Mineral exploration • Security Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 16. Magnetometers - Principles of Operation Hall Effect Magnetometer Lorentz Force - Benefits- •Solid-state •Low Temperature Sensitivity •Highly Linear •Small •Cheap Drawbacks- •Saturation limit •Calibration Issues Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 17. Magnetometers - Principles of Operation Ordinary Magnetoresistive Sensor •Applied voltage creates a radial current •Applied magnetic field creates a circular current •This alters the path of an electron, making it travel in a spiral, increasing the length traveled and resistance Quantum Mechanical Effects •Anisotropic Magnetoresistance •Giant/Colossal Magnetoresistance •Tunneling Magnetoresistance Corbino Disc Magnetometer-based Accelerometer Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
- 18. Conclusion • The history and applications of accelerometers • Overview of G-Force • Operation of Capacitive accelerometers • Two types of magnetometers o Scalar o Vector • Applications of magnetometers • Operation of Hall Effect Magnetometer Introduction Magnetometer Background Accelerometer Fundamentals Accelerometer Background Magnetometer Fundamentals Conclusion and Questions
Editor's Notes
- #15: Navigation Compass Mineral exploration - Oil- insects consume hydrocarbons and create magnetite Military applications - submarines Archaeology- can find buried stones, rocks, bricks, basalt and granite. Security- Airport metal detectors