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By R. Peter Bonasso, R. James Firby, Erann Gat, David Kortenkamp, David P Miller, Marc G Slack Presented By Tony Morelli 9/16/2004. Experiences with an Architecture for Intelligent Reactive Agents. Abstract. 3T Robot Architecture 3 Levels of abstraction
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By R. Peter Bonasso, R. James Firby, Erann Gat, David Kortenkamp, David P Miller, Marc G Slack Presented By Tony Morelli 9/16/2004 Experiences with an Architecture for Intelligent Reactive Agents
Abstract • 3T Robot Architecture • 3 Levels of abstraction • Variety of software tools have been created to implement this on multiple real robots • Has been implemented on several different robot systems with different processors, operating systems, effectors, and sensors.
Introduction • Three interacting layers • Dynamically reprogrammable set of reactive skills cooridnated by a skill manager • Sequencer that controls skills to accomplis a specific task. Use the Reactive Action Packages (RAP) • Deliberative planner that reasons in depth about goals, resources and timing constraints. Use the Adversarial Planner (AP)
Software Tools for Arcitechture Implementation • A number of tools were developed for integrating the three tiers together and providing the user with a paradigm for developing robotic applications
Skills • Input and Out Specification – Each skill must provide a description of the inputs it expects and the outputs it generates • Computational Transform – The actual work • Initialization Routine – What to do on power up • An Enable Function • A Disable Function
Sequencing • Accomplish routinely performed tasks • Task is dependent upon the robot's knowledge of the situation. • Replies are through skills called events. • Events take inputs from other skills • Events notify the sequencer when a desired state has been detected. • Lacks the foresite to achieve global behavior
Planning • Operates at the highest level of abstraction to make its problem space as small as possible • Using the AP planner • Multiagent control (robots usually have interaction with either people or other robots) • Robots need to be able to work together • CounterPlanning --- Need to do change plans when something an uncontrolled agent enters the picture.
Applications of the Architecture • Discuss the robot. • Describe the task, the skills, the RAPs, and the plans • Give results and lessons learned of the architecture
A Mobile Robot that Recognizes People • Search for a particular color shirt • Crop the face and identify the person • Skills – Searching and tracking colors, cropping the face, recognizing the face, and obstacle avoidance. • 20 RAPs to disable/enable skill sets and recover from errors. • Did not use the planning tier of the architecture
A Trash Collecting Mobile Robot • Named Chip • Skills – Moving while avoiding obstacles, face a particular direction, finding an object visually, tracking an object, and reaching towards an object. • Middle tier combined low level RAPs to make higher level RAPs • No upper tier • Successful in their experiments
A Mobile Robot that Navigates Office Buildings • Use sonar data for obstacle avoidance and laser scanner with bar coded tages for landmark recognition. • Skills – Watching for landmarks, moving to landmarks, and moving through doorways. • RAPs for moving to a landmark or moving through a set of connecting spaces. • Planner can plan a new path if the hallway is blocked.
Space Station Robots • Plans are made by humans and sent to the planner • The planner creates a series of RAPs. • Simple failures are handled at the RAP level • Drastic failures will could cause the planner to abandon all plans • Implemented on a simulator prior to real life. • Differences were in the interfaces and the level of autonomy. The planner and the RAPs were basically unchanged.
Allocating Knowledge Across the Architecture • Time – Skill level has time in milliseconds, sequencer in tenths of a second, and the planning level in seconds. • Bandwidth – Skills are high bandwidth (image transferring). Between skill system and the RAP is small (enable/disable). • Task Requirements – A RAP should be broken down into skills. If a RAP starts doing look ahead, it should be considered an AP.
Allocating Knowledge Across the Architecture (2) • Modifiability – Skills are compiled into runtime events. RAP and planner are based on interpreters and their behavior can be changed by changing RAP descriptions and planning operators.
Comparison With Other Work • 2 Categories of autonomous agents • Control physically embedded agents • Explore issues in general intelligence • 3T an example of the first
Robot ArchitecturesSubsumption • Subsumption – Decomposes robot control by task, rather than function. • No architectural support for abstraction, planning or resource management.
Robot ArchitecturesSSS • Three layer architecture • Subsumption is the middle layer • Only been demonstrated on tasks involving pure navigation
Robot ArchitecturesTask Control Architecture • No tiers • Cumbersome to have a general planner • All failures are lumped together • 3T handles failures at all three levels
Non-robotic Agent Architectures • Guardian – Similar to 3T but with sequencing and deliberation performed by the same mechanism • Decision making can be faster • Cypress – Their version of RAPs were difficult to integrate as they were not designed to allow integration with conventional AI planners
Future Work and Conclusions • Division of labor permits the generalization of knowledge across multiple projects. • 3T can ease the development of software control code. • 3T use in non-robotic control systems • WWW Robot (retrieves maps to fight fires) • Closed Ecological Life Support Systems • Determine the planting cycles of various crops