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1、Inertial Technology惯性技术惯性技术付振宪付振宪School of Astronautics, HIT1Lecture 1 - IntroductionAbout the courseInertial Navigation（惯性导航）惯性导航）:GPS（Global Positioning System 全球定位系统）全球定位系统）Devices:q Gyroscopes (陀螺仪陀螺仪)q Accelerometers (加速度计）加速度计）Systems:q Platform inertial navigation systems （平台式惯导系统）平台式惯导系统）q S
2、trapdown inertial navigation systems （捷联惯导系统）捷联惯导系统）2Lecture 1 - Introduction1.0 NavigationNavigation- providing information about vehicles motion, such as position, velocity and attitude.Relationship between - Navigation, guidance, and controlControllerActuatorPositionVelocityAttitudeNavigation3Lec
3、ture 1 - Introduction1.1 Types of navigationq Landmark NavigationSince primitive ancient time (not limited to human beings)q Astronomical NavigationBy observation of celestial bodies, such as sun, stars, planets or the moon4Lecture 1 - Introduction1.1 Types of navigationq Satellite Navigation GPS, G
4、LONASS, Galileo, Bei Dou (Northern Star) q Dead Reckoning Navigation (DR 定位推算定位推算)Current position = initial position + covered displacementInertial Navigation System (INS)5Lecture 1 - Introduction2.1 Inertial navigation: InertiaInertiaThe tendency of a physical object to remain still or continue mo
5、ving, unless a force is applied to it - Collins Dictionary.q Inertia of mass point - massq Inertia of rigid body - angular inertia （转动惯量）转动惯量）6Lecture 1 - Introduction2.2 Newtons LawsInertial navigation and Newtons laws q 1st law: Inertial lawq 2nd law: Dynamic equationq 3rd law: Action and reaction
6、 Inertial navigation is based on the measurement of vehicles acceleration ( using accelerometers - 加速度计加速度计).mSensitivity axisInfluence of gravitation7Lecture 1 - Introduction2.3*Basic ideaRelationship between position, velocity and acceleration :Characteristics of inertial navigation: q Autonomous
7、(自主自主 self-contained)q No external information is requiredq Relying merely on inertial measurement of the the vehicleq Continuous and robust output 8Lecture 1 - Introduction2.4 Two-Dimensional Case Planar (two-dimensional) navigationvehicleplatformOutputs of accelerometers are integrated twice to ob
8、tain position of vehicle.Acc. XAcc. Yq During navigation, the platform need to track the OXY frame.q Stabilization of the platform is achieved with help of gyroscopes (陀螺仪陀螺仪). Platform or Strapdown9Lecture 1 - Introduction3.1 Gyroscope General concept From ancient Greek: : Rotation sensor Tradition
9、al conceptGyro: Spinning rigid body Gyroscope: Gyro + Suspension, so as to measure rotationToy gyro: q Spinning axis tends to be stableq Stability is prone to disturbance Disturbance factors q Friction q Unbalance10Lecture 1 - Introduction3.2 SuspensionInnovation of suspension -gimbals(框架框架) Outer R
10、ing axisOuter Ring Inner Ring Inner Ring axisRotor axisRotorBaseEquivalent supporting point Degree of freedom (DOF) - the rotors- the spinning axis2-DOF gyroscope (spinning axis) RotoraxisRotorBaseInnerringInnerringaxis1-DOF gyroscope11Lecture 1 - Introduction3.3 Drift and drifting rate q Drift - ch
11、ange of orientation of gyros spinning axis with respect to inertial space due to disturbanceq Drift rate - angular rate of drift （deg/h）Drift (漂移漂移) and drifting rateq Precision of navigation - inertial grade: 0.01deg/h有害力矩有害力矩q History of gyros - reducing detrimental torques and drift12Lecture 1 -
12、Introduction4.0 History of gyroBohnenbergers Machine, 181313Lecture 1 - Introduction4.0 History of gyro Work of Foucault (傅科傅科)French physicist (1819-1868)To verify the spinning of the earthFoucault Pendulum(1851)L = 67mM =28kgD = 6mPantheon in Paris14Lecture 1 - Introduction4.1 Foucaults workFoucau
13、lt gyroscope (1852)EarthExperiment not successful Later improvements15Lecture 1 - Introduction4.2 History: marine applicationq Magnetic compass (罗盘罗盘) was applied in early marine navigationq Late 19th century, replacement of wooden-hull ships by iron-hull ones made magnetic compass less useful. q Li
14、mitation on magnetic compass near the polesq Searching for new direction indicators16Lecture 1 - Introduction4.2 History: Gyro compassGyro was a promising candidate, but with problem finding local north.In 1908, gyro compass was invented by Anschutz (Germany) In 1909, Sperry invented gyro compass to
15、o. Burgeoning(发端发端) of modern application of gyroscopic techniques17Lecture 1 - Introduction4.3 History: aerial navigationq Since 1920s, application in airplanes Attitude of aircraftsazimuthrolling pitching q Gyro horizonq Azimuth indicator18Lecture 1 - Introduction4.4 History: early missilesq 1930s
16、, Pioneering study by Goddard (US)q 1940s, V-1、V-2 V-1: cruising missile (1942)Massively used in WWIISince June, 1944，10500 launched.V-2 : ballistic missile 1700 launched19Lecture 1 - Introduction4.5 History: Cold War competitionAfter WWII，German experts shifted to US and USSR (Van Braun)Competition
17、 between US and USSRSputnik I, 1957Explorer I, 1958Braun20Lecture 1 - Introduction4.5 History: fluid suspensionEarly 1950s，Fluid suspension gyroscope was developed by Draper Lab, MITrotorInner ring(Gyro chamber)Outer ring21Lecture 1 - Introduction4.6 History: journey of Argonaut1958，Journey of Argon
18、aut submarinePearl Harbor - Bearing Strait - North Pole - Portland 21days，15000 Km Marking the maturity of inertial navigation 22Lecture 1 - Introduction5.0 Two trendsTwo trends： q Higher precisionq Lower cost and size (for SINS)5.1 Higher precisionImproved gimbal suspension - fluid, gas, magneticAc
19、hieving 10 e-7 deg/h 23Lecture 1 - Introduction5.1 Higher precision: ESGElectrically suspended gyro (ESG)：using non-contact suspension CeramichullsphericalrotorspinningaxissphericalelectrodesTi ionpumpq Proposed in 1952 (Nordsieck)q Application in late 1970sq Achieving 10e-7 deg/h q 10e-11 deg/h by
20、StanfordDisadvantages：Complexity and cost24Lecture 1 - Introduction5.2 Lower cost and sizeRing laser gyro (RLG 环形激光陀螺环形激光陀螺) Developed since early 1960s, applied in 1970sFiber Optical Gyro (FOG 光纤陀螺光纤陀螺)Developed since 1970s, applied since early 1980s25Lecture 1 - Introduction5.2 Fiber Optical Gyro
21、(FOG)Developed since 1970s, applied in early 1980sFOGs rapid increase in use Mech.RLGFOG26Lecture 1 - Introduction5.2 Vibratory gyroVibratory gyros (振动陀螺振动陀螺)q Tuning fork (音叉音叉)q Piezoelectric gyro (压电压电)q Hemi-spherical resonant gyro (HRG 半球谐振半球谐振)q MEMS (微机电系统微机电系统)Micromachined Electro-Mechanica
22、l Systems27Lecture 1 - Introduction6.0 Evolution of INSPlatform inertial navigation system (PINS, or INS)(later C.S. Draper Lab)1950s - first INS by MIT Instrumentation Lab 1960s - widespread1980s - contraction in applicationStrapdown inertial navigation system (SINS)1960s - Idea proposed1970s - Mat
23、ured theories, futile production1980s - Rapid expansion of applications. 28Lecture 1 - IntroductionResourcesPPT downloading:http:/ (within campus only)Textbooks： Strapdown Inertial Navigation Technology- digital only惯导系统陀螺仪原理惯导系统陀螺仪原理 - digital onlyExam: Close book, close noteContact: 86413411-8506, 1520469466229Lecture 1 - Introduction
