GNSS/INS Product Design Cycle. Taking into account MEMS-based IMU sensors

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1 GNSS/INS Product Design Cycle Taking into account MEMS-based IMU sensors L. Vander Kuylen 15 th th December 2005

2 Content Product Definition Product Development Hardware Firmware Measurement Campaign in Challenging Environment December 19, Septentrio N.V. 2

3 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, Septentrio N.V. 3

4 Product 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, Septentrio N.V. 4

5 Product 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, Septentrio N.V. 5

6 Product 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, Septentrio N.V. 6

7 Product 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, Septentrio N.V. 7

8 Product 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, Septentrio N.V. 8

9 Content Product Definition Product Development Hardware Firmware Measurement Campaign in Challenging Environment December 19, Septentrio N.V. 9

10 Measurement Campaign in Challenging Environment GPS does not suffer from crane tail cranes are open structures signal-obstruction is limited: signal loss is brief GPS antenna is placed above error sources December 19, Septentrio N.V. 10

11 Measurement Campaign in Challenging Environment PolaRx2 High-end GPS-receiver SBAS PVT, Prototype MEMS-based IMU Sensors: Analog Devices: accelerometers (XYZ) and gyroscopes(xy) Motorola: gyroscope (Z) Measurement Vicinity of cranes: Low/No GPS visibility (DOP) Degraded position solution December 19, Septentrio N.V. 11

12 Measurement Campaign: GPS based PVT GPS-based solution (red) North [m] East [m] December 19, Septentrio N.V. 12

13 Measurement Campaign: Integrated PVT North [m] Integrated GPS/IMU solution (blue) 5 m 5 m GPS-based solution (red) East [m] December 19, Septentrio N.V. 13

14 Measurement 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 December 19, Septentrio N.V. 14

15 Thank you! Leen Vander Kuylen Navigation Research & Development Please visit our website December 19, Septentrio N.V. 15