@inproceedings{
   Author = {Kottege, Navinda and Zimmer, Uwe R.},
   Title = {Acoustical methods for azimuth, range and heading estimation in underwater swarms},
   BookTitle = {Acoustics '08},
   Address= {Paris,  France},
   Note  = {http://www.ncbi.nlm.nih.gov/pubmed/18529348},
   Abstract = {Robotic swarms and specifi cally schools of semi-autonomous underwater vehicles are becoming more and more of a
reality. An essential feature required in most such systems is an effi cient and precise relative localisation system. Specifi c,
common requirements include posture estimations of multiple neighbours, controllable sensing ranges, as well as high
robustness and accuracy.
The presented system is based on acoustically transmitted MLS (Maximum Length Sequence) -signals. Multiple receivers
allow for precise azimuth and range measurements, while multiple transponders additionally allow for complete posture
estimations of neighbouring vehicles. The short baselines (< 200 mm) given by the dimensions of the vehicles in the
swarm make sub-sample interpolations in the post-cross-correlation phase necessary. Furthermore the deployment of low
cost transducers and hydrophones in a broadband signal setup requires specifi c fi ltering methods.
For the experimental setup as depicted in detail in the article, a mean error nDi in the bearing (azimuth) estimation i is
less than 0.3º throughout all experiments, while the mean error nDa in the heading estimation a of a neighbouring vehicle
is always less than 5.0º. Experiments have been performed in many confi gurations in a inter-vehicle distance of up to 5 m,
while the mean range error nDr remains well below 10 mm. All experiments have been performed in fresh water.},
   Keywords = {direction-of-arrival estimation
distance measurement
multi-agent systems
multi-robot systems
optical communication
position control
radiocommunication
underwater acoustic communication
underwater vehicles
MLS signals
Serafina project
acoustic localization
communication system
high interference deployability
high interference robustness
information fusion
longwave radio band
low cost localization method
maximum lengths sequence signals
relative position information
relative posture information
small submersibles
submersible azimuth estimates
submersible heading estimates
submersible range estimates
submersible schools
swarm coordination
wideband acoustic readings},
   Year = {2008} }