gnss/ins product design cycle taking into account memsmems ... der kuylen, nin, dec 2006.pdf ·...
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GNSS/INS Product
Design Cycle
GNSS/INS Product GNSS/INS Product
Design CycleDesign Cycle
Taking into account
MEMS-based IMU sensors
Taking into account Taking into account
MEMSMEMS--based IMU sensorsbased IMU sensors
L. Vander Kuylen
15th December 2005
L. Vander Kuylen
15th December 2005
December 19, 2006 ©2006 Septentrio N.V. 2
ContentContent
� Product Definition
� Product Development� Hardware � Firmware
� Measurement Campaign in Challenging Environment
December 19, 2006 ©2006 Septentrio N.V. 3
Integrating MEMS-based IMU Integrating MEMS-based IMU
� Increased usage of GNSS receivers in industrial applications� Short GNSS-outage periods
� Development of MEMS-based IMU sensors� Small� Low-power consumption� Cheap
December 19, 2006 ©2006 Septentrio N.V. 4
Product DefinitionProduct Definition
� Goal:� Mainly to increase availability of reliable position
solution� Provide an attitude solution
� IMU sensor shall� Be cost effective� Provide an accurate IMU-based position during
periods of GNSS outage
� Optimal solution: application dependent
December 19, 2006 ©2006 Septentrio N.V. 5
Product DefinitionProduct Definition
� Applications� Industrial and agriculture applications
� Regular short periods of GNSS outage� Low-visibility areas when driving next to buildings/trees
� Orientation of vehicle
� UAVs� Orientation of vehicle
� Interested in MEMS IMU due to small size and low-power consumption
� Maritime applications� Orientation of vehicle
December 19, 2006 ©2006 Septentrio N.V. 6
Product DefinitionProduct Definition
� Types of IMU sensors� Navigational-grade
� LN92 (Northrop Grumman), etc.� Export licence constraint
� 100,000 €
� Tactical-grade IMU sensors� HG1700 (Honeywell), LN-200 (Northrop Grumman), etc.
� Possibly export licence constraint
� 15,000 € - 20,000 €
� Low-grade IMU sensors� Xsens, Crossbow, BEI Technologies, VIT Engineering, etc.� MEMS-based� 1,000 € - 10,000 €
December 19, 2006 ©2006 Septentrio N.V. 7
Product Development: HardwareProduct Development: Hardware
� Commercial Of The Shelf (COTS) IMU� Increase flexibility for different applications
� Integration firmware runs on receiver CPU
� IMU measurements are provided to receiver through RS232 COM-interface
December 19, 2006 ©2006 Septentrio N.V. 8
Product Development: FirmwareProduct Development: Firmware
� Firmware Development for MEMS-based IMU
� Loosely-coupled Integration: � Data fusion in position, velocity,
time domain � 2 decentralized (Kalman) Filters� Closed-loop
� Advantages compared to tightly-coupled integration:
� Better fault detection performance
� Less complexity � Less computational effort
� Disadvantages compared to tightly-coupled integration:
� Less availability� Less accurate
December 19, 2006 ©2006 Septentrio N.V. 9
ContentContent
� Product Definition
� Product Development� Hardware � Firmware
� Measurement Campaign in Challenging Environment
December 19, 2006 ©2006 Septentrio N.V. 10
Measurement Campaign in Challenging
Environment
Measurement Campaign in Challenging
Environment
GPS antenna is placed above error sources
cranes are open structures
signal-obstruction is limited: signal loss is brief
GPS does not suffer from crane tail
December 19, 2006 ©2006 Septentrio N.V. 11
Measurement Campaign in Challenging
Environment
Measurement Campaign in Challenging
Environment
� PolaRx2 High-end GPS-receiver� SBAS PVT, available @1Hz
� Prototype MEMS-based IMU� Sensors:
� Analog Devices: accelerometers (XYZ) and gyroscopes(XY)
� Motorola: gyroscope (Z)
� Measurement processing @100Hz
� Vicinity of cranes:� Low/No GPS visibility (DOP)� Degraded position solution
December 19, 2006 ©2006 Septentrio N.V. 12
Measurement Campaign: GPS based PVTMeasurement Campaign: GPS based PVT
GPS-based
solution (red)
Nort
h [m
]
East [m]
December 19, 2006 ©2006 Septentrio N.V. 13
Measurement Campaign: Integrated PVTMeasurement Campaign: Integrated PVT
Nort
h [m
]
East [m]
≈≈≈≈ 5 m
≈≈≈≈ 5 m
GPS-based
solution (red)
Integrated GPS/IMU
solution (blue)
December 19, 2006 ©2006 Septentrio N.V. 14
Measurement Campaign: ConclusionsMeasurement Campaign: Conclusions
� Error growth using MEMS-based IMU� 05 sec GPS outage ⇒ 2.5m horizontal position error� 10 sec GPS outage ⇒ 5m horizontal position error� 30 sec GPS outage ⇒ 80m horizontal position error
� Conclusions� Results are not perfect, due to
� IMU sensor used
� Models used in integration filter
� Usage of low-quality IMU improves availability of reliable position solution in challenging environments
� Depending on the vehicle motion, constraints can be used to improve the solution
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