A Bio-inspired Collision Avoidance Model Based on Spatial Information Derived from Motion Detectors Leads to Common Routes

Abstract

Avoiding collisions is one of the most basic needs of any mobile agent, both biological and technical, when searching around or aiming toward a goal. We propose a model of collision avoidance inspired by behavioral experiments on insects and by properties of optic flow on a spherical eye experienced during translation, and test the interaction of this model with goal-driven behavior. Insects, such as flies and bees, actively separate the rotational and translational optic flow components via behavior, i.e. by employing a saccadic strategy of flight and gaze control. Optic flow experienced during translation, i.e. during intersaccadic phases, contains information on the depth-structure of the environment, but this information is entangled with that on self-motion. Here, we propose a simple model to extract the depth structure from translational optic flow by using local properties of a spherical eye. On this basis, a motion direction of the agent is computed that ensures collision avoidance. Flying insects are thought to measure optic flow by correlation-type elementary motion detectors. Their responses depend, in addition to velocity, on the texture and contrast of objects and, thus, do not measure the velocity of objects veridically. Therefore, we initially used geometrically determined optic flow as input to a collision avoidance algorithm to show that depth information inferred from optic flow is sufficient to account for collision avoidance under closed-loop conditions. Then, the collision avoidance algorithm was tested with bio-inspired correlation-type elementary motion detectors in its input. Even then, the algorithm led successfully to collision avoidance and, in addition, replicated the characteristics of collision avoidance behavior of insects. Finally, the collision avoidance algorithm was combined with a goal direction and tested in cluttered environments. The simulated agent then showed goal-directed behavior reminiscent of components of the navigation behavior of insects.

A Bio-Inspired Model for Visual Collision Avoidance on a Hexapod Walking Robot

“…For each starting position 3 trajectories were simulated. In all cases the robot successfully reached the goal position without collisions and without encountering local minima (see however [1] for a more detailed analysis). Natural Cluttered Environment.…”

“…Once the relative nearness map μ r is known, collision avoidance is achieved by moving away from the maximum nearness value (e.g. objects that are close) (see [1]). However, the contrast-weighted nearness map also depends on the textural properties of the environment.…”

“…The inverse of the COM AN V vector, scaled to the horizontal field of view θ of the photoreceptor array, points away from the closest object and, thus, can be used as the direction of the robot to avoid collisions (collision avoidance direction, CAD fov ; Fig. 2D; [1]):…”

“…Recently, a simple model for collision avoidance based on EMDs was proposed [1]. The model is based on three successive processing steps: (a) the extraction of (contrast-weighted) nearness information from optic flow by EMDs, (b) the determination of a collision avoidance direction from the map of nearness estimates and (c) the determination of a collision avoidance necessity, i.e.…”

“…• panoramic vision used in [1], a fisheye lens was mounted on the front segment of the robot with its main optical axis pointing forward, limiting the field of view for retrieving optic flow information.…”