Steering Behaviors

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Steering Behaviors

• What are Steering Behaviors
• means of locomotion for autonomous agentsand
  robots.
• largely independent
• can be combined
• improvisational and reactive

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Steering Behaviors

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

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Steering Behaviors

• primarily based on
• Steering Behaviors For
• Autonomous Characters
• by Craig Reynolds
• Presented by Kevin M. Kelly

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Steering Behaviors
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Flocking

• Designed for Computer Animation (Reynolds '87)

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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/

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Current Uses

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

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Steering Behaviors

• Architecture from theInternational
  GameDevelopers Association

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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

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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

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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

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Vehicle Model

• Steering behaviors give a force or acceleration
  vector
• Could extrapolate to more complex vehicles

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Examples (single behavior)

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

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Seek and Flee

• http//www.red3d.com/cwr/steer/SeekFlee.html

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Pursue and Evade

• http//www.red3d.com/cwr/steer/PursueEvade.html

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Wander

• http//www.red3d.com/cwr/steer/Wander.html

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Arrival

• http//www.red3d.com/cwr/steer/Arrival.html

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Obstacle Avoidance

• http//www.red3d.com/cwr/steer/Obstacle.html

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Containment and Wall Following

• http//www.red3d.com/cwr/steer/Containment.html
• http//www.red3d.com/cwr/steer/Wall.html

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Path Following

• http//www.red3d.com/cwr/steer/PathFollow.html

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Examples (combined behaviors)

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

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Crowd Path Following

• Weighted Combination of
• Path Following
• Separation
• http//www.red3d.com/cwr/steer/CrowdPath.html

Path Following
Separation
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Leader Following

• Combination of
• Separation
• Arrival (point slightly behind the leader)
• http//www.red3d.com/cwr/steer/LeaderFollow.html

Arrival
Separation
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Unaligned Collision Avoidance

• Combination of
• Containment
• Unaligned Collision Avoidance
• http//www.red3d.com/cwr/steer/Unaligned.html

Containment
Unaligned Collision Avoidance
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Queuing

• Combination of
• Seek
• Containment
• Separation
• http//www.red3d.com/cwr/steer/Doorway.html

Seek
Separation
Containment
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Flocking

• Combination of
• Alignment
• Cohesion
• Separation
• http//www.red3d.com/cwr/boids/

Separation
Alignment
Cohesion
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Conclusions

• Simple behaviors can create realistic looking
  effects
• Looks more natural than fully planned
• Easy combination created for Flocking does not
  work with everything