Autonomous boids

Abstract

The classical work of bird-like objects of Reynolds simulates polarized motion of groups of oriented particles, bird-like objects, or simply boids. To do this, three steering vectors are introduced. Cohesion is the tendency of boids to stay in the center of the flock, alignment smoothes their velocities to similar values, and separation helps them to avoid mutual collisions. If no impetus is introduced the boids wander somewhat randomly so an external leading force is necessary for the correct flock behavior. As can be observed during the bird flocking in the fall, birds sometimes move in a way that is not captured by the above described framework. Some of the birds, typically the ones on the edge of the flock, suddenly shoot-off. The flock then pursues this leader. In the original work by Reynolds the cohesion and separation are two complementary steers. We introduce a complementary force to the alignment that we call the change of leadership. This steer defines the chance of the boid to become a leader and try to escape. The leadership is derived from the boid position and the flock eccentricity. If a boid is on the front edge of the flock it has a higher chance to escape. Escaping from the flock is simulated as a sequence of velocity increases that are added to the current velocity of the boid. The entire system is easy to implement, is efficient, and runs simulations of hundreds of boids on a standard computer at 30 frames per second. Our system is aimed to real-time simulations and has the potential to be used in games, crowd simulations, etc.

Lessons from research on interaction with virtual environments

“…There are not only algorithms for controlling the behaviour of an autonomous animal, but there are also algorithms for controlling a flock (or a herd, or a school) of virtual animals which obtain impressive animations. The most famous of these flocking algorithms is boids (Reynolds, 1987) which has been extended in several ways since Reynolds proposed it (see for instance Go et al, 2004;Hartman and Benes, 2006). Boids has been used to animate the behaviour of flocks in famous movies, but it is rarely used to populate interactive virtual environments.…”

Robotic Herding of a Flock of Birds Using an Unmanned Aerial Vehicle

“…Reynolds [9] formulated simple motion behaviors (collision avoidance, velocity matching, and flock centering) for creating computer animations of bird flocks and simulating the stable collective motion seen therein. Reynolds' model has formed the basis for other flocking models such as the self-propelled particle model [10], [11] and a leader-based modification of Reynolds' model [12]. Alongside theoretical modeling, attempts have been made to extract flocking rules, aggregate patterns, and ordering from empirical studies on large flocks of birds and fish [13], [14].…”

Agent-Based Evacuation in Passenger Ships Using a Goal-Driven Decision-Making Model

“…This section describes a crowd-movement model that is a combination of models for social force [10,11] and steering behavior [21,22]. Analogous to the social-force model, this model uses the laws of mechanics to calculate the agents' movement during the simulation.…”