Optic-flow-based Altitude and Forward Speed Regulation using Stereotypical Lateral Movements

We propose a novel optic-flow-based flight control strategy, inspired by recent observations and hypothesis by Baird (unpublished), to regulate independently forward speed and altitude. Unlike previous approaches where longitudinal ventral optic flow was used to regulate both forward speed and altitude, we suggest to use transversal ventral optic flow generated by a stereotyped lateral oscillation to regulate altitude. Longitudinal ventral optic flow is still used to regulate forward speed. The main advantage of this strategy is to allow any combination of forward speed and altitude, which is not possible by using exclusively longitudinal ventral optic flow. We show that this control strategy allows to control a helicopter- or insect-like simulated agent with any combination of forward speed and altitude. Moreover, thanks to a modulation of the open-loop oscillatory drive of the roll behaviour, this strategy achieves roll stabilisation.