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Towards Artificial ATRON Animals:Scalable Anatomy for Self-Reconfigurable Robots

David J. Christensen, David Brandt & Kasper Støy

Robotics: Science & Systems Workshop on Self-Reconfigurable Modular Robots

August 2006

David Johan ChristensenPh.D-Student

Adaptronics Group, Mærsk InstituteUniversity of Southern Denmark

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Overview

• Why study Self-Reconfigurable robots?• The ATRON system.• Scaling the robot.• Challenge of Scalable Functionality• Scalable Anatomy for ATRON robots• Discussion, Future work & Summary

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Why Study Self-Reconfigurable Robots?

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Purpose from Scientific Perspective?

• Understand, explain and recreate the characteristics of life!!

Biological Organism

Biological Organism

CellsCells

BiologicalSpecies

BiologicalSpecies

Self-OrganizeSelf-Assemble (Chemicals)Self-Reproduce (Division)

Self-SufficientSelf-Contained

Self-MaintainedAutonomousAdapt & LearnSelf-AssembleSelf-RepairSelf-Reproduce

Intelligent & Conscious

EvolveCEBOTCATOMCONROM-TRAN3D-UNITFRACTA

POLYBOTMOLECULESUPERBOTMOLECUBE

CRYSTALLINEMETAMORPHICMany other …….

RobotRobot

RoboticModules

RoboticModules

RoboticSpecies

RoboticSpecies

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Purpose from Engineering Perspective?

• We want to build Better Robots!• Why should it Modular?

– Multi-Purpose => Versatility (by clever design)– Mass-Produce => Low Cost – Extendable => Scalable

• Why should it be Self-Reconfigurable?– Self-Repair => Reliable & Robust (from redundancy)– Self-Assembly => Automated Production– Adaptation => Increased Performance (both functional and

morphological adaptation)

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ATRON

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Our Platform: The ATRON System

• Module Characteristics:– Single degree of freedom– 4 male, 4 female connectors– Batteries (had power sharing)– Computation, communication, – Sensing: Distance, Tilt, Encoders– 800 grams pr. module

• Manufactured: 100 modules

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Versatility of the ATRON System

• Manipulation & Locomotion

(Real Time)

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Versatility of the ATRON System

• Self-Reconfiguration

(8x Speed)

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Scaling

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• Scaling down module size (cm to µm)• Scaling up number of modules (tens to millions)

• Why?– Closer to the cell metaphor. – Improve engineering metrics (e.g. resolution of shape)

Scaling the Robot

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Scalability Challenges of Self-Reconfigurable Robots

• What are the Challenges?

– Hardware• What to build?

– Self-Reconfiguration• Morph between configurations.

– Functionality (THIS TALK!)• Fast responding and functional robots.

– Many other challenges….

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Challenge of Scalable Functionality

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Number of Cells/ModulesThe Challenge of Scalable Functionality

Speed of Response

Complexity of Functionality

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What is the problem anyway?

• Self-Reconfiguration too slow: (for fast response)– Slower with more modules (more moving)– Faster with smaller modules (faster modules)

• Modules are locked rigidly:– Modules are stuck in a global lattice.– Actuation Forces does not add up.

• So scaling functionality is hard.– Functionality do not transfer from a 10 to a 1000 module robot

Functionality reduces to self-reconfiguration.

Basically constant with volume.

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How can we approach the problem?

Artificial Creature

Artificial Creature

RoboticModules

RoboticModules

Computers, Actuators, Sensors, Gears…

ScalableAnatomy

ScalableAnatomy

• How to build Myriad-Module Robots?– Functional & Fast-Responding

• Approach: Defining a Robot Anatomy– Biological Inspired by Animal Anatomies– Scalable Anatomically Structures

• Bone, joints, muscles, nerves, etc..

Scalable Anatomy

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Where does this comes from?

CellsCells

TissuesTissues

OrgansOrgans

AnimalAnimal

ModulesModules

CellularInspiration

AnatomicallyStructures

AnatomicallyStructures

RobotRobot

Anatomi Inspiration

• Hieratical Organization of cells• Differentiation dependent on role in organism

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ATRON Anatomy

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Moving from idea to system…

• ATRON Anatomy– ATRON-Nerve– ATRON-Arteries – ATRON-Bone– ATRON-Joint– ATRON-Muscle– ATRON-Skin

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ATRON Anatomy: Neurons and Arteries

Notation

• ATRON-Artery– Transportation of energy ~ Power sharing

• ATRON-Neuron– Computation ~ Microprocessors– Coordination ~ IR-Communication– Sensing ~ Sensors

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ATRON Anatomy: Bone

Femur Bone ATRON Bone

• ATRON-Bone– Support Weight of Robot.– Strong Connector.– Lattice Interconnection.– Scales in 3D.

0.067MPa*

720kg/m^3

ATRON-Bone

1900 kg/m^3Density

50MPaYield Strength

Bio-Bone

*Østergaard et al., Design of the ATRON lattice-based self-reconfigurable robot. Autonomous Robots, to appear, 2006.

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ATRON Anatomy: Hinge Joint

Hinge Joint

• ATRON-Joints – Connection and relative rotation of bones.

• Hinge Joint– Scales along rotational axes.– Reversible to global lattice.

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ATRON Anatomy: Ball-Socket Joints

Ball-Socket JointHip Joint

• ATRON-Joints – Connection and relative rotation of bones.

• Ball-Socket Joint– Scalable in 3D.– Reversible to global lattice using muscles

as anchors.

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ATRON Anatomy: Muscle

• ATRON-Muscles– Actuation of myriad-module robot– Parallelizable to achieve scalability

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ATRON Anatomy: Skin

• ATRON-Skin– Purpose: e.g. protection from environment.– ATRON Surfaces that can deform and stretch– However:

• Rigid constraints on ATRON

• Full of Holes

Two sheets patterns for skin

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Discussion, Future work & Summary

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Lesson Learned…

• Will it ever work?– Probably not with the ATRON alone…

• Why not?– Morphological differentiation of modules seems necessary:

• Functional differentiation are not enough.• 210 different cell types in adult human

• What then? (Future work)– Collect more experience from different systems:

• Which anatomical structures?• How to combine anatomical structures?

– Design novel SR system based on scalable anatomy.

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Summary

• Challenge of Scalable Functionality:– Fast responsive functionality myriad-module robots…

• Our Approach:– Biological Inspired Scalable Anatomy.– Anatomical Parts: Bone, Joint, Muscle, Skin, Nerve.

• Scalable Anatomy for ATRON System.

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