  Biological evidence shows that animals are capable of evading eminent
collision without using depth information, relying solely on looming stimuli.
In robotics, collision avoidance among uncooperative vehicles requires
measurement of relative distance to the obstacle. Small, low-cost mobile robots
and UAVs might be unable to carry distance measuring sensors, like LIDARS and
depth cameras. We propose a control framework suitable for a unicycle-like
vehicle moving in a 2D plane that achieves collision avoidance. The control
strategy is inspired by the reaction of invertebrates to approaching obstacles,
relying exclusively on line-of-sight (LOS) angle, LOS angle rate, and
time-to-collision as feedback. Those quantities can readily be estimated from a
monocular camera vision system onboard a mobile robot. The proposed avoidance
law commands the heading angle to circumvent a moving obstacle with unknown
position, while the velocity controller is left as a degree of freedom to
accomplish other mission objectives. Theoretical guarantees are provided to
show that minimum separation between the vehicle and the obstacle is attained
regardless of the exogenous tracking controller.
