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Cooperative Navigation for Groups of Autonomous Underwater Vehicles. ASAP Hot Wash Meeting – November 2006. What navigation information do we have?. GPS: Only for surface(d) vehicles Dead-reckoning: Compass+speed est. → Error: 10% dist. traveled
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Cooperative Navigation for Groups of Autonomous Underwater Vehicles ASAP Hot Wash Meeting – November 2006
What navigation information do we have? GPS: • Only for surface(d) vehicles Dead-reckoning: • Compass+speed est.→ Error: 10% dist. traveled • Doppler Velocity Logger→ Error: 1% dist. traveled→ Distance < 200 m to bottom or surface • Inertial Navigation System→ Error: 0.2% dist. traveled→ Expensive ($100,000) Navigation error grows without bound for DR, DVL and INS !
How about Sharing Navigation Information Other vehicles may know better where they are and share this information Examples: • Solar AUV on surface • Surfaced glider • AUV with more sophisticated INS
Requirements for Cooperative Navigation • Acoustic modem (WHOI): • Maximum range: 200 m - 4 km • Maximum data rate: 3 bytes/s - 1 kByte/s • Power consumption: 100 mW in receive mode • Precise clock • Synchronized at surface to GPS clock • Drift O(Milliseconds per hour) • Enable one way ranging to transmitting vehicles • Bandwidth for transmitted information • Position, position uncertainty, (heading, pitch, speed) • Necessary information is contained in most CCL packages • Vehicle-to-vehicle range for free
Cooperative Navigation Research at MIT • ASAP/MB06 experiment in Monterey, CA, August 2006: Kayak to AUV Kayak to Kayak Kayak to Glider • Boston: • (In cooperation • with Bluefin) • Publications: Alexander Bahr, John J. Leonard, Cooperative Localization for Autonomous Underwater Vehicles, In Proceedings of the 10th International Symposium on Experimental Robotics (ISER) , Rio de Janeiro, Brasil, July 2006
Upcoming • Theory and Algorithms • Development of new Cooperative Navigation algorithms • Comparing performance by post processing collected data sets • Defining the minimal amount of necessary information which needs to be transferred • Experiments • AUVs: • Kayak to AUV in real-time, AUV to AUV (first post-processing, then real-time) • Glider: • Dedicated Cooperative Navigation experiment with gliders • Kayak to glider, glider to glider (real-time, post-processing)
Autonomous CTD casts Kayak outfitted with CTD on winch (70 m cable, 10 min/station) • Predetermined pattern (Iuliu Vasilescu) • Autonomous gradient following (Don Eickstedt)