From optic flow sensors to optic flow based guidance
Senior research scientist
Institute of Movement Science, CNRS – Aix Marseille Université, France
Flying insects such as honeybees are endowed with several sensory modalities, but the optic flow appears to be the main cue for their guidance and flight control [1, 2, 3]. We showed recently that robots equipped with new optic flow sensors and optic flow regulators are able to control their course without requiring a state vector describing their absolute speed, position or altitude [4, 5, 6]: the robots trajectories mimic the insects’ trajectories even in the presence of wind [4, 6]. By applying optic flow criteria, these robots manipulate forces by the way of rotor and thruster speed and thus adjust their speed of flight, their lateral position or their altitude [4, 5] in various tunnels . This optic flow based steering control system makes them avoid obstacles even in unstable environments  without any need for maps and even without any measurement and control of its absolute pitch . These biomimetic robotic behaviors may explain how flying insects used regionalized optic flow criteria to guide themselves in various tunnels (see  for review).
 G. Portelli, J. R. Serres & F. Ruffier (2017) Open Access “Altitude control in honeybees: joint vision-based learning and guidance”, Scientific Reports 7, Article number: 9231, doi:10.1038/s41598-017-09112-5
 G. Portelli, F. Ruffier, F.L. Roubieu, N Franceschini. (2011) “Honeybees’ Speed Depends on Dorsal as Well as Lateral, Ventral and Frontal Optic Flows”, PLoS ONE 6(5): e19486. doi:10.1371/journal.pone.0019486
 G. Portelli, F. Ruffier, N. Franceschini (2010) “Honeybees change their height to restore their Optic Flow”, Journal of Comparative Physiology A, Springer, 196(4):307-313
 F. Ruffier, N. Franceschini (2005) “Optic flow regulation: the key to aircraft automatic guidance”, Robotics and Autonomous Systems, Vol. 50, No 4, 31 March 2005, pp. 177-194
 F. Ruffier, N. Franceschini (2014) “Optic Flow Regulation in Unsteady Environments: A Tethered MAV Achieves Terrain Following and Targeted Landing Over a Moving Platform”, J. Intell. Robot Syst., Springer, DOI 10.1007/s10846-014-0062-5
 F. L. Roubieu, J. R. Serres, F. Colonnier, N. Franceschini, S. Viollet, F. Ruffier (2014) “A biomimetic vision-based hovercraft accounts for bees’ complex behaviour in various corridors” Bioinspiration & Biomimetics, IOP, 2014, 9(3) 036003 (22pp)
 J. R. Serres and F. Ruffier (2015) “Biomimetic autopilot based on minimalistic motion vision for navigating along corridors comprising U-shaped and S-shaped turns”, Journal of Bionic Engineering (Elsevier), 12 (1), pp. 47 – 60
 F. Expert and F. Ruffier (2015) Open access “Flying over uneven moving terrain based on optic-flow cues without any need for reference frames or accelerometers”, Bioinspiration and Biomimetics, IOP, 10, 026003
 J. R. Serres and F. Ruffier (2017) Open Access “Optic flow-based collision-free strategies: From insects to robots”, Arthropod Structure & Development, ISSN 1467-8039, doi:10.1016/j.asd.2017.06.003.
Franck Ruffier received an engineering degree in 2000 and a PhD degree from INP-Grenoble in 2004, as well as a habilitation to supervise research from Aix-Marseille University in 2013. He was visiting scientist invited by Prof. Michael Dickinson, Univ. of Washington, Seattle, USA in 2012 as well as in 2008 by Dr. T. Mukai at RIKEN, Nagoya, Japan. Franck Ruffier published more than 70 papers in international Journals and referred Proceedings including Science, PNAS and Current Biology as well as 12 book chapters and 10 patents. His present position is CNRS Research Director at the Institute of Movement Science (ISM). His main areas of interest are insect-inspired vision and aerial robotics.