@inproceedings{Alenya_ecmr09,
  author = {Aleny{\`a}, G. and N{\`e}gre, A. and Crowley, J.L.},
  title = {Time to contact for obstacle avoidance},
  booktitle = {Proceedings of the European Conference on Mobile Robotics},
  year = {2009},
  pages = {19-24},
  url = {http://www.iri.upc.edu/publications/show/1024},
  file = {http://www.iri.upc.edu/download/scidoc/1024}
}