Steering Behaviors

● What are Steering Behaviors means of locomotion for autonomous agents

and robots. largely independent can be combined improvisational and reactive

Steering Behaviors

● What Steering Behaviors are NOT action plan searching puzzle-solving anything needed global information

Steering Behaviors

primarily based on: Steering Behaviors For Autonomous Characters

by: Craig Reynolds

Presented by: Kevin M. Kelly

Steering Behaviors

Flocking

● Designed for Computer Animation (Reynolds '87)

Flocking

● Steering behaviors grew from “Flocking”● Craig Reynolds “Boids”

Three separate steering behaviors combined● Separation● Cohesion● Alignment

Combined by simple vector addition● Flocking Demo:

http://www.red3d.com/cwr/boids/

Current Uses

● Now used for many purposes Computer animation in movies Video games Simulations Robotics

Steering Behaviors

● Architecture from theInternational GameDevelopers Association

Parts of the Steering Architecture

● Steering World Interface provides information about the world

● Steering Behaviors the behaviors themselves – each output

independent steering goals● Arbitrator

combine the steering goals (this is very difficult)● Actuator

Actual movement code – specific to the application

Arbitrator

● The arbitrator is the most difficult part of using steering behaviors

● Flocking used the simplest form of arbitrator simple combination

● Other types of arbitration Prioritized (much like Brooks's actuated control) Heuristic

● application dependent Reverse

● select best one of each Round Robin

● each gets a turn

Vehicle Model

● Simple Vehicle Model (could be 2D or 3D) a “Mass Point” Has the following attributes

● mass● position● velocity● max_force● max_speed● orientation

updated at each time step

Vehicle Model

● Steering behaviors give a force or acceleration vector

● Could extrapolate to more complex vehicles

Examples (single behavior)

● Seek● Flee● Evasion● Pursuit● Wander● Arrival● Obstacle Avoidance● Containment● Wall Following● Path Following

Seek and Flee

● http://www.red3d.com/cwr/steer/SeekFlee.html

Pursue and Evade

● http://www.red3d.com/cwr/steer/PursueEvade.html

Wander

● http://www.red3d.com/cwr/steer/Wander.html

Arrival

● http://www.red3d.com/cwr/steer/Arrival.html

Obstacle Avoidance

● http://www.red3d.com/cwr/steer/Obstacle.html

Containment and Wall Following

● http://www.red3d.com/cwr/steer/Containment.html

● http://www.red3d.com/cwr/steer/Wall.html

Path Following

● http://www.red3d.com/cwr/steer/PathFollow.html

Examples (combined behaviors)

● Crowd Path Following● Leader Following● Unaligned collision avoidance● Queuing● Flocking

Crowd Path Following

● Weighted Combination of Path Following Separation

● http://www.red3d.com/cwr/steer/CrowdPath.html

Path Following

Separation

Leader Following

● Combination of Separation Arrival (point slightly behind the leader)

● http://www.red3d.com/cwr/steer/LeaderFollow.html

Arrival

Separation

Unaligned Collision Avoidance

● Combination of Containment Unaligned Collision Avoidance

● http://www.red3d.com/cwr/steer/Unaligned.html

Containment

Unaligned Collision Avoidance

Queuing

● Combination of Seek Containment Separation

● http://www.red3d.com/cwr/steer/Doorway.html

Containment

SeparationSeek

Flocking

● Combination of Alignment Cohesion Separation

● http://www.red3d.com/cwr/boids/

Cohesion

SeparationAlignment

Conclusions

● Simple behaviors can create realistic looking effects

● Looks more natural than fully planned● Easy combination created for Flocking does not

work with everything