Integrated Inertial Positioning Systems - Zupt, LLC

1 Zupt, LLCI ntegrated Inertial Positioning SystemsSome facts, some editorial and some biased opinionsZupt, LLCI nertial Tools -What instruments are currently in daily use for Survey?In our businessInertial navigation Systems (INS) for land seismic, Vertical Reference Units (VRU s) for DP, USBL/SBL and Swath sonar attitude/heave corrections Surface heading sensors Spinning mass gyros as well as strap down Attitude Heading Reference Systems (AHRS)In other applicationsInertial sensors -anti-lock brakes, anti skid, virtual reality headsets Analog Devices, Crossbow, Systron, Bosch, BAe and many othersInertial Navigation Systems as (Tactical) short term positioningsensors -Northrop Grumman, Honeywell, Kearfott, BAe, Boeing, precision (Strategic) Inertial Navigation Systems for long term Positioning outages -Northrop Grumman, Honeywell, Thales navigation, , LLCA vailable How Long?

2 In discussing this exciting new technology we must also understand that these tools have been around for a while, even in the seismic and survey business:Western Geophysical sW-INS ( we invariably needed SHORAN )late 1970 sShelltech/Itech land seismic use of INS for control (helicopter based Zupt s) Mid/late 1970 sExxon/Honeywell s DP reference Systems Riser and INS 1979 British Oceanics/Intersub INS for manned submersible construction Positioning (used in place of the unreliable acoustic Systems ) early 1980 sZupt, LLCS ession AgendaA few definitionsWhat is an Inertial measurement unit (IMU)? overview of Inertial sensorsPrice versus performanceWhere is Inertial technology going? Integrated Inertial Positioning SystemsLoosely, tightly and deeply coupledAiding Observations current and futureApplications for Integrated Inertial Positioning SystemsCurrent and near term productsCommercial benefits of these systemsZupt, LLCA few definitionsAn Inertial Sensoris a position, attitude or motion sensor whose reference are completely internal draft revision to IEEE Std 528A Gyroscopeis a sensor designed to illustrate the dynamics of a rotating bodyIn Strapdownoperations the Inertial frame of reference is stored in the computer as opposed to being maintained mechanically by transformations and sensor compensation have to be completed within the strapdown input.

3 But some level of outputAngle random walk-white spectrum rate detection noise leads to an angle random walk (optical and coriolis gyros) Aiding-using external non Inertial observations to minimize biasScale Factor-an error in the assumed scale factor in the instrument outputSchuler Oscillation/Period-84 minutes just think about a pendulum centered at the earth s core and the IMU at the earth s surface Zupt, LLCWhat does an IMU consist of?Zupt, LLCHow does this fit together?MeasureaccelerationCompensate foraccelerometerbias and SFCompensatefor gravityIntegrateOnce-VelocityTwice-Dista nceMeasurerotation ratesCompensateforEarth s rotationNavigation ComputerAccelerometersGyrosHeadingDistan ceSpeedCompensate for Gyro Bias, ARW, SF and acceleration sensitivities Zupt, LLCO verview of Inertial sensorsInertial sensors come in many forms and are an excuse for infinite acronym two types of sensors within an IMU are:Gyroscopes -rate of rotation Accelerometers -linear accelerationSome examples are:Gyros Dynamically tuned, (DTG), Fiber Optic (FOG), Ring laser (RLG)Accels Vibrating Beam (VBA), Quartz Resonating (QRA), Pendulous Mass (PMA)Zupt, LLCGyro TechnologyAngular Rate Sensing technology principles.

4 Spinning Mass -angular momentumVibratory/Resonator -Coriolis Optical -SagnacMicro Electro Mechanical Sensor(MEMS)primarily vibratory, some spinning mass, some opticalMicro Optical Electro Mechanical Sensor (MOEMS) another variantZupt, LLCC urrent Gyro technologyZupt, LLCMore Gyro detailsSpinning Mass Honeywell, Northrop Grumman, RockwellProsWide performance range to >100 /hrVery low noise -(specifically gas bearing)ConsRelatively high costLong warm upNot well suited to strapdown applicationsSome types very fragileVibratory/Resonant Watson, Systron Donner, Murata, BAeProsRelatively smallMinimum moving partsConsSmall scale factorOutput noisyRate gyro open loopLimited performance range (getting better though)Zupt, LLCPros and ConsOpticalHoneywell, Northrop Grumman, (Fibresense), Ixsea, Sagem, reaction and turn on(<1s)Ideally suited for strapdown operationNo moving parts -very ruggedConsPerformance increases with sizeRLG is a high voltage deviceFOG very temperature sensitiveMicro Electro (MEMS) Draper/Honeywell, JPL, BAe, AD, Bosch, etc.

5 (only vibratory discussed) ProsVery smallNo moving partsVery low costConsHigher precision still under developmentLimited performance range (only for a while) Bias stabilityZupt, LLCFOG block Bias ( /hr) is usually proportional to length of fiberThe longer the fiber -the better the FOGZupt, LLCRLG Block blockPath lengthcontrol mirrorAnodeAnodeOpticalbeamsMirrorCathod e-Schematic of ring laser gyro. Input axis is perpendicularto the plane of Bias ( /hr) is usually proportional to path lengthThe longer the path length -the better the RLGZupt, LLCA ccelerometer TechnologyLinear acceleration sensing technologies:Pendulous/Translational Mass displacement/rebalanceElectrical RestraintRotational RestraintElastic RestraintResonant Element FrequencyVibrating StringVibrating BeamDouble Ended Tuning ForkZupt, LLCC urrent Accelerometer TechnologyZupt, LLCMore accel.

6 DetailsForce Rebalance Accels -Honeywell Q-Flex, Northrop Grumman A4, Kearfott Mod VIIProsHighly Reliable -relatively low costWide bandwidthLow bias errorConsAnalog outputself heating under changing accelerationPower consumptionPendulous Rebalance , rugged, smallWell understood error modelPendulous Integrating Gyro Accel. (PIGA) as good as it getsused for ICBM and general missile guidanceConsPIGA -CostResonant Element Accel. Sundstrand, Allied Signal AdkemProsDigital outputLow powerConsNot good in high shock environmentDetailed calibration requiredZupt, LLCS ensor Advances -MEMSW afer thick gyros -400 mCritical assembly process for MEMSA ssembly issues being worked on tomake a low cost, mass produced instrument .Noise is the challenge I-O have low noise,low G product VectorSeis Zupt, LLCMEMS DoD Development ProgramA low cost, high G MEMS and guidanceeffort is underway for a DoD joint forces program.

7 This effort has the following goals:Phase 1<75 /hr, >10,000G, <8 cubic inchesThis phase should have been delivered3 vendors selected 2 delivered 4 months agoPhase 2<10 /hr, >20,000G, <4 cubic inchesThis phase should be delivered this/next year2 vendors selected one ready to deliverPhase 3< /hr desired (<1 /hr acceptable), >20,000G launch survivable, <2 cubic inches volume. DoD s cost expectation for this IMU is <$1,200 Should have been delivered in 2006 may not be needed due to deeply coupled Phase coupled L1 and L2/Lm, WAAS, SAASM GPS receiver should be incorporated as an option to Phase 2/3 Zupt, LLCSo how good is a good INS?Once the sensors (just discussed) have been combined to make an Inertial Measurement Unit software has to be added to turn the raw rate (incremental rate-?)

8 ?) and the raw acceleration (incremental velocity-?V)data into something useful as a:Attitude Heading Reference System (AHRS), or an Inertial Navigation System (INS)The performance of an INS is usually rated in terms of its position error growth rate once the INS is navigating in free Inertial mode (no aiding). The USAF define INS in the following manner:INS ClassificationPosition Error Growth RateHeading ErrorsLow> 2nm/hr> to 2 to Precision< < Following a standard ground alignment at 50 or lower latitude USAF SNU84-1 Zupt, LLCCost versus PerformancePRICE $K160 Department of State Controlled TechnologyDept. of Commerce Controlled ?Primarily for internationallysourced IMU's onlyIMAR .003 $155K 20cm RLG140120100 Thales Totem .001 Thales $100K 30cm RLGT24.

9 003 $130K Kearfott 24cm RLGLN250 .005 ? $90K 1200m? FOG80LN100 .003 $80K Northrop 18cm RLGPHINS .003 $80K Ixsea 1200m FOGCIMU .0035 $80K Honeywell 6" path RLGS igma 10 .05 SAGEM $65K 10cm RLG 60 Octans $60K Ixsea 700m FOG (AHRS only)40T16 .01 $100K Kearfott 18cm RLGT90 1 $39K Tamam 20LN200 1 $22K Northrop 200m FOGBOEING 3 $20K STAB /hrZupt, LLCW here is this technology going?Zupt, LLCM aturity of technologyDraper Laboratory s view on the state of current development. The suggestion is that most technologies are now mature except for MEMS , LLCE xport ControlThe fastest way to go to jail (without passing go) will be to flaunt the export controls associated with this International Traffic in Arms Regulations (ITAR) and the Arms Export Control Act (AECA) are the governing law that is overseen through the Directorate of Defense Trade Controls (DDTC ) within the Department of State (remember Colin Powell).

10 Simply put (to me by the DDTC) if you screw up, it will be you,not the company, that goes to jail .DDTC is responsible for all licensing issues if the commodity iscontrolled by get a commodity under the more understanding Dept. of Commerce control a Commodity Jurisdiction has to be filed with the US manufactured and high end international IMU s will fall under the control of the DDTC Do not listen to the vendors when they say don t worry about this talk to your own export attorney and get their , LLCWhat type of sensor do you need to buy/integrate? As can be seen from the previous charts IMU s are available in many flavors. The one underlying suggestion I would make is to:Only buy the sensor with the performance you really needDo not over specify the performance requirements of your sensor or it will cost significantly more than it , LLCFree Inertial Drift$100K buys apx.