The ATRON Self-reconfigurable Robot challenges and future directions Kasper Støy AdapTronics Group The Maersk Institute for Production Technology University of Southern Denmark Kasper Støy AdapTronics Group The Maersk Institute for Production Technology University of Southern Denmark

ATRON Terrestrial Self-Reconfiguration Henrik H. Lund, Esben H. Ostergaard Richard Beck, Lars Dalsgaard, Morten W. Jorgensen Associated: Kristian Kassow, Leonid Paramonov, Kasper Støy, David Christensen, David Brandt, Danny Kyrping Maersk Institute, University of Southern Denmark, Denmark

Self-reconfigurable robots

ATRON Concept  Key insight: 3D self-reconfiguration can be achieved even-though each module only has one rotational degree of freedom

Mechanics : Prototype 0 Concept: Using arms for alignment and screw to connect Produced in 3D printer Concept: Using arms for alignment and screw to connect Produced in 3D printer

Mechanics : Prototype 1A  Connector Concept  Two arms parallel to equator  Test of connector  Too weak  Connector Concept  Two arms parallel to equator  Test of connector  Too weak

Mechanics : Prototype 1B  Connector Concept  Trippel Hooks  Dual bars  Test of connector  Prototype broke  Connector Concept  Trippel Hooks  Dual bars  Test of connector  Prototype broke

Mechanics : Final Prototype  Improved main bearing  Improved connector- mechanism  Improved main bearing  Improved connector- mechanism

Electronics  Two hemispheres  Two sets of main processors  Connector actuation  Hemispheres connected by slipring  One power management processor  Sensors  Two hemispheres  Two sets of main processors  Connector actuation  Hemispheres connected by slipring  One power management processor  Sensors

Electronics : Power Supply  Manages recharging  Shares power  Selects best power source  Monitors the organism power supply  Regulates power  600 batteries sponsored by Danionics  Manages recharging  Shares power  Selects best power source  Monitors the organism power supply  Regulates power  600 batteries sponsored by Danionics

Current Mechanics

Final Module Design

IROS Demonstration videos  Misalignment correction  Double rotation  Power sharing  Misalignment correction  Double rotation  Power sharing

Concept Demonstations  David Christensen  Meta module demo (ATRON Demo 1)  Jakob Stampe Mikkelsen  Walker  David Christensen  Meta module demo (ATRON Demo 1)  Jakob Stampe Mikkelsen  Walker

Explored control concepts  Local control  Local rules (Esben H. Østergaard)  Gradients and scaffolds (Kasper Støy)  Meta modules (David Christensen)  Centralized control  Planning (David Brandt)  Local control  Local rules (Esben H. Østergaard)  Gradients and scaffolds (Kasper Støy)  Meta modules (David Christensen)  Centralized control  Planning (David Brandt)

Gradients and scaffold

Local Rules Esben Østergaard

Meta modules David Christensen

Conclusion  Control achievements  Control is difficult, but experience gained  ATRON Achievements  Innovative connector design  Innovative lattice structure resulting in  Simplified modules  Easier control…  Control achievements  Control is difficult, but experience gained  ATRON Achievements  Innovative connector design  Innovative lattice structure resulting in  Simplified modules  Easier control…

Intermezzo Queen of Denmark admires ATRON module together with the Japanese emperor

The Cruel Reality of Self- Reconfigurable Robots Kasper Støy AdapTronics Group The Maersk Institute for Production Technology University of Southern Denmark Kasper Støy AdapTronics Group The Maersk Institute for Production Technology University of Southern Denmark

Vision of self-reconfigurable robots  Robust  Versatile  Cheap  Robust  Versatile  Cheap

The Reality of Self- Reconfigurable Robots  Fragile  Useless  Expensive  Fragile  Useless  Expensive

Robust vs Fragile  Robustness comes from redundancy  If a module fails it can be ejected and other modules can take over  Graceful degradation of performance  Robustness comes from redundancy  If a module fails it can be ejected and other modules can take over  Graceful degradation of performance USC’s ISI

Robust vs Fragile  Difficult to detect if a module has failed  Due to motion constraints it is difficult to eject the failed module  Due to weakness of modules it may not be possible to eject the failed module at all  Difficult to detect if a module has failed  Due to motion constraints it is difficult to eject the failed module  Due to weakness of modules it may not be possible to eject the failed module at all

Versatile vs Useless  A self-reconfigurable robot can change into any shape needed for the task

Versatile vs useless  In practice motion constraints make it difficult to change shape

Versatile vs useless  In practice motion constraints make it difficult to change shape

Versatile vs useless David Brandt Start Goal

Versatile vs useless  Too weak to interact with the world  The ATRON and the MTRAN robots can only lift in the order of a few modules  Too weak to interact with the world  The ATRON and the MTRAN robots can only lift in the order of a few modules

Cheap vs Expensive  ATRON $2000  MTRAN $3500  ….  ATRON $2000  MTRAN $3500  ….

The Reality of Self- Reconfigurable Robots  Fragile!  Useless!  Expensive!  Fragile!  Useless!  Expensive!

Challenges of self-reconfigurable robots  How do we  Make robot strength greater than O(1)?  Reduce motion constraints to facilitate easy self-reconfiguration?  Reduce the consequences of module failure?  Reduce module complexity (cost)? …while maintaining our successful results  How do we  Make robot strength greater than O(1)?  Reduce motion constraints to facilitate easy self-reconfiguration?  Reduce the consequences of module failure?  Reduce module complexity (cost)? …while maintaining our successful results

Make robot strength greater than O(1)?  Use module weight to gain leverage (seesaw)  Crystalline/Telec ube parallel chains  ….  Use module weight to gain leverage (seesaw)  Crystalline/Telec ube parallel chains  ….

Reduce module complexity (cost)?  ATRON is a step forward, but further - no idea… Reduce module complexity (cost)?  ATRON is a step forward, but further - no idea… Reduce the consequences of module failure? No idea

Reduce motion constraints to facilitate easy self-reconfiguration?  Metamodules  Scaffold  Telecube  Metamodules  Scaffold  Telecube

Hypothesis  The challenges cannot only be addressed at the level of control  The challenges have to be addressed by new innovative hardware design  The challenges cannot only be addressed at the level of control  The challenges have to be addressed by new innovative hardware design

Challenges of self-reconfigurable robots  How do we design the module to  Make robot strength greater than O(1)?  Reduce motion constraints to facilitate easy self-reconfiguration?  Reduce the consequences of module failure?  Reduce module complexity (cost)? …while maintaining our successful results  How do we design the module to  Make robot strength greater than O(1)?  Reduce motion constraints to facilitate easy self-reconfiguration?  Reduce the consequences of module failure?  Reduce module complexity (cost)? …while maintaining our successful results

Deformable Modular Robots  All modules are permanently connected in a lattice  Modules can only contract or expand (limited but flexible crystalline module)  All modules are permanently connected in a lattice  Modules can only contract or expand (limited but flexible crystalline module)

Concept Demonstration  Physical implementation  Deformatron  Hexatron  Simulation  Physical implementation  Deformatron  Hexatron  Simulation

Deformable Modular Robots  Make robot strength greater than O(1)?  Through parallelisms  Reduce motion constraints to facilitate easy self-reconfiguration?  Done  Reduce the consequences of module failure?  Done  Reduce module complexity (cost)?  No connectors …while maintaining our successful results  Shape change within limits  No self-replicating robot  Make robot strength greater than O(1)?  Through parallelisms  Reduce motion constraints to facilitate easy self-reconfiguration?  Done  Reduce the consequences of module failure?  Done  Reduce module complexity (cost)?  No connectors …while maintaining our successful results  Shape change within limits  No self-replicating robot

Conclusion  Self-reconfigurable robots are facing serious challenges  Increase strength, reduce motion constraints, increase fault tolerance, reduce complexity (price)  Radical new hardware designs needed  Deformable modular robots may be able to sidestep the hardest problems, but at a cost  Self-reconfigurable robots are facing serious challenges  Increase strength, reduce motion constraints, increase fault tolerance, reduce complexity (price)  Radical new hardware designs needed  Deformable modular robots may be able to sidestep the hardest problems, but at a cost