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Published on October 15, 2007

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Biological Foundations of the Reactive Paradigm:  Biological Foundations of the Reactive Paradigm Review Why? -comp. theory IRM Perception -Summary Describe the three levels in a Computational Theory. Explain in one or two sentences each of the following terms: reflexes, taxes, fixed-action patterns, schema, affordance. Be able to write pseudo-code of an animal’s behaviors in terms of innate releasing mechanisms, identifying the releasers for the behavior. Given a description of an animal's sensing abilities, its task, and environment, identify an affordance for each behavior. Given a description of an animal's sensing abilities, its task, and environment, define a set of behaviors using schema theory to accomplish the task. Robots In the Hierarchical Paradigm:  Robots In the Hierarchical Paradigm Timeline of Influences:  Timeline of Influences 1980 1990 1970 Braitenberg’s Vehicles Arbib’s Schemas Tinbergen & Lorenz & von Frisch Marr’s Computational Theory J.J. Gibson Neisser Middlestat Arkin’s Schemas Brook’s Insects Payton Marr’s Computational Theory:  Marr’s Computational Theory Level 1: Existence Proof:  Level 1: Existence Proof Goal: how to make line drawings of objects? people can do this by age 10, computers should Level 2: Inputs, Outputs, Transforms:  Level 2: Inputs, Outputs, Transforms light drawing retina (gradient) light lines (edges) drawing Level 3: Implementation:  Level 3: Implementation + - - - - - - - - Center Surround Cell in retinal ganglion Class Discussion:  Class Discussion Give three examples of how biology has informed modern technology? ex. Wright Brothers- control flaps on airplane wings Behavior Definition (graphical):  Behavior Definition (graphical) BEHAVIOR Sensory Input Pattern of Motor Actions Types of Behaviors:  Types of Behaviors Reflexive stimulus-response, often abbreviated S-R Reactive learned or “muscle memory” Conscious deliberately stringing together WARNING Overloaded terms: Roboticists often use “reactive behavior” to mean purely reflexive, And refer to reactive behaviors as “skills” Ethology: Coordination and Control of Behaviors:  Ethology: Coordination and Control of Behaviors Nobel 1973 in physiology or medicine von Frisch Lorenz Tinbergen www.nobel.se Arctic Terns:  Arctic Terns Arctic terns live in Arctic (black, white, gray environment, some grass) but adults have a red spot on beak When hungry, baby pecks at parent’s beak, who regurgitates food for baby to eat How does it know its parent? It doesn’t, it just goes for the largest red spot in its field of view (e.g., ethology grad student with construction paper) Only red thing should be an adult tern Closer = large red behavior template:  behavior template BEHAVIOR Sensory Input Pattern of Motor Actions “the feeding behavior”:  “the feeding behavior” Feeding BEHAVIOR Sensory Input Pattern of Motor Actions RED PECK AT RED the releaser template:  the releaser template Sensory input and/or internal state “the feeding releaser”:  “the feeding releaser” Feeding BEHAVIOR RED PECK AT RED Releaser present? N Y /dev/null internal state RED & HUNGRY sensory input Innate Releasing Mechanisms:  Innate Releasing Mechanisms BEHAVIOR Sensory Input Pattern of Motor Actions Sensory input and/or internal state Example: Hide Behavior:  Example: Hide Behavior Programmed in C++, << 100 LOC shows taxis (oriented relative to light, wall, niche) fixed action pattern (persisted after light was off) reflexive (stimulus, response) impliciting sequencing use of internal state Example: Cockroach Hide:  Example: Cockroach Hide light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out even if the lights are turned back off earlier Reflexive Behaviors S-R:  Reflexive Behaviors S-R light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out even if the lights are turned back off earlier Fixed Pattern Actions:  Fixed Pattern Actions light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out even if the lights are turned back off earlier Exhibits Taxis:  Exhibits Taxis light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out even if the lights are turned back off earlier to light to wall to niche Class Exercise:  Class Exercise Draw flowchart of how this works Break into Behaviors:  Break into Behaviors light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Find Releasers:  Find Releasers light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N Internal State Set:  Internal State Set light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N BLOCKED & SCARED present? N SCARED Action:  Action light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N BLOCKED & SCARED present? N SCARED steer 360, drive forward steer =F(dist to wall) drive forward const. steer =F(dist to wall) drive forward const. stop Sensory Input:  Sensory Input light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N BLOCKED & SCARED present? N SCARED steer 360, drive forward steer =F(dist to wall) drive forward const. steer =F(dist to wall) drive forward const. stop encoders IR IR IR IR IR How Do You Link Them?:  How Do You Link Them? light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N BLOCKED & SCARED present? N SCARED steer 360, drive forward steer =F(dist to wall) drive forward const. steer =F(dist to wall) drive forward const. stop encoders IR IR IR IR IR Analogy: IRMs work on THREADS, not sequential processing!:  Analogy: IRMs work on THREADS, not sequential processing! Very simple modules Nice building blocks since not directly linked If one module (part of brain) fails, what happens? What happens when there’s a conflict from concurrent behaviors?:  What happens when there’s a conflict from concurrent behaviors? Equilbrium Feeding squirrels-feed, flee: hesitate in-between Dominance Sleepy, hungry: either sleep or eat Cancellation Sticklebacks defend, attack: build a nest ? Perception :  Perception Two uses of perception (can be the same percept) Release a behavior Guide a behavior Action-oriented perception (Neisser) Planning is not needed to act Perception is selective Gibson’s Ecological Approach:  Gibson’s Ecological Approach Acting and sensing co-evolved as agent survived in a particular environment. The environment affords the agent what it needs to survive. The perception needed to release or guide the “right action” is directly in the environment, not inferred or memorized Ex. Red on Artic Terns== food Ex. Sound of filling container==full Percepts are called affordances or said to be obtained through direct perception Gibsonian Affordances:  Gibsonian Affordances How do you know you’re going fast in a car? Or in a space movie? How do animals know when to mate? How do mosquitoes know to bite in the most tender areas? What should you do when you think you’re being stalked by a mountain lion? What’s your favorite fishing lure? Sittability:  Sittability But does this really hold for everything?:  But does this really hold for everything? “my car” versus “your car”? Difference is where I parked it (memory) Semantic meaning (cars aren’t generic like nuts to a squirrel) Neisser’s Two Systems Direct Perception: older, behavioral Recognition: evolved later, deliberative Review Questions:  Review Questions What are the levels of a computational theory? Existence proof, inputs-outputs-transformations, implementation What is a behavior? A behavior is a mapping of sensory inputs to a pattern of motor actions Is sequencing normally implicit or explicit in IRM? implicit What is an affordance? A potentiality in the environment for an action Schema Theory:  Schema Theory schema- is used in cognitive science and ethology to refer to a particular organized way of perceiving cognitively and responding to a complex situation or set of stimuli is generic, equivalent to an object in OOP schema specific knowledge (local data) procedural knowledge (methods) schema instantation is specific to a situation, equivalent to an instance in OOP a behavior is a schema, consists of perceptual schema motor schema Behavioral Schema:  Behavioral Schema Motor Schema (MS) Perceptual Schema (PS) percept, gain action, intensity alternative PS, MS sequencing logic for reactive skills (judgment value function) Reflexive behaviors usually just have “methods”, not data Ex. Fly Snapping Behavior IRM:  Ex. Fly Snapping Behavior IRM snap(blob) track(blob) x,y,z, 100% snap, 100% Releaser: small moving dark blob present? N Y /dev/null Schema Instantiation (SI):  Schema Instantiation (SI) snap(blob) track(blob) x,y,z, 100% snap, 100% Releaser: small moving dark blob present? N Y /dev/null Schema/Schema Instantiation:  Schema/Schema Instantiation Advantages:  Advantages modular can assemble new behaviors from existing schemas learning by experimentation can substitute alternatives reroute nerves Instantiation for each eye:  Instantiation for each eye snap, 100% snap(blob) track(blob) x,y,z, 100% Releaser: small moving dark blob present? N Y /dev/null snap, 100% snap(blob) track(blob) x,y,z, 100% Releaser: small moving dark blob present? N Y /dev/null Left eye Right eye Where’s the MS and PS?:  Where’s the MS and PS? light goes on, the cockroach turns and runs when it gets to a wall, it follows it when it finds a hiding place (thigmotrophic), goes in and faces outward waits until not scared, then comes out Flee Follow- wall hide Y SCARED & SURROUNDED present? N BLOCKED & SCARED present? N SCARED steer 180, drive forward steer =F(dist to wall) drive forward const. steer =F(dist to wall) drive forward const. stop encoders IR IR IR IR IR General Principles:  General Principles All animals possess a set of behaviors Releasers for these behaviors rely on both internal state and external stimulus Perception is filtered; perceive what is relevant to the task Some behaviors and associated perception do not require explicit knowledge representation (e.g., rely on affordances) Silicon v. Carbon:  Silicon v. Carbon Individual robots must survive, not species detection of non-productive behaviors graceful degradation Must be able to predict emergent behaviors Not clear how to learn quickly Robots need more alternative perceptual schemas since poorer understanding of the environment Unresolved Issues:  Unresolved Issues How to resolve conflicts? behavioral arbitration/combination When is explicit representations, memory needed? How to set up or learn new sequences of behaviors What are the affordances for a particular ecology? Take Home Thoughts…:  Take Home Thoughts… Ideas bubbling up for robotics Maybe programming in terms of behaviors is better than STRIPS or trying to set up a complex hierarchy Intelligence has something to do with agent’s ecological niche: its abilities, its tasks (survival), and environment Perception is going to be critical because it releases and guides actions IRMs, Schemas are nice ways to start thinking about the computational structure of programming a robot Review Questions:  Review Questions Think about the robots at the WTC. What are affordances of victims? color, motion, sound, heat Can schema theory represent behaviors in both biological and computational systems? yes A behavior schema is composed of at least the following: motor schema and a perceptual schema What is an example of behavior-specific knowledge? sequencing in a skill, alternative PS or MS Inhibition:  Inhibition while (TRUE) { predator = sensePredator(); //has a time delay if (predator==PRESENT) //as long as predator persists flee(); else { food = senseFood(); hungry = checkStateHunger(); ... } } Could also be done as an interrupt

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