BBR Architectures

Subsumption

• Developed by Rodney Brooks in the Mid-1980ies
• Comes with a whole "philosophy" about how to design robots: strongly opposed to the "sense-plan-act" loop of classical robotics (remember Shakey?)
• Core features:
• anti-representationalist - "the world is its best model" (Brooks 1991)
• anti-"deliberatist" - "planning is just a way of avoiding figuring out what to do next" (Brooks 1987)
• anti-realist with respect to intelligence - "intelligence is in the eye of the beholder" (Brooks 1991)
• emphasizes control systems that are
• simple
• cheap
• robust
• autonomous
• parallel
• hierarchical
• incrementally extensible
• keywords:
• situated
• embedded
• Basic component: augmented finite state machine (AFSM)
• Why augmented? Because there are additional control mechanisms (e.g., for timing, resetting)
• Inhibition, suppression and reset links (to inhibit inputs, suppress and replace outputs of AFSMs, as well as to reset them)
• Subsumption architectures then consist in an arrangement of layers, each of which contains one or more AFSMs
• Difficult to specify interactions between AFSMs

• for easier use: behavior language (abstraction over AFSM)

• Behavior coordination is competitive:
• layered dominance hierarchy of AFSMs (i.e., higher ones dominate lower ones)
• Arbitration mechanisms between layers may use any of the three links

Motor Schemas

• Arbib, Arkin, et al.
• Biologically inspired ("Schema theory", also: motor control in insects)
• Reactive in nature (functional sensory-motor mapping):
• uses force or potential fields to map sensory space into motor space
• Cooperative behavior coordination (through summation of fields!)
• Continuous response encoding

Examples of Fields and their Combinations

• Obstacle

• Goal:

 
• Combination:

• Path taken by the agent:


 
• Corridor following:

 
• Complex composite task:

• Issue: local minima


 
• Solution: add random noise!

• To get out of larger wells:

• Add "aoivd-past-scheme":

• Allows agents to traverse mazes, for example: